Environmental Monitoring in Emergency Situations

Transcription

1 SAFETY \ 0» Jt SERIES No. 18 Environmental Monitoring in Emergency Situations INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1966

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3 ENVIRONMENTAL MONITORING IN EMERGENCY SITUATIONS

4 The following States are Members of the International Atomic Energy Agency: AFGHANISTAN FEDERAL REPUBLIC OF NICARAGUA ALBANIA GERMANY NIGERIA ALGERIA GABON NORWAY ARGENTINA GHANA PAKISTAN AUSTRALIA GREECE PANAMA AUSTRIA GUATEMALA PARAGUAY BELGIUM HAITI PERU BOLIVIA HOLY SEE PHILIPPINES BRAZIL HONDURAS POLAND BULGARIA HUNGARY PORTUGAL BURMA ICELAND ROMANIA BYELORUSSIAN SOVIET INDIA SAUDI ARABIA SOCIALIST REPUBLIC INDONESIA SENEGAL CAMBODIA IRAN SOUTH AFRICA CAMEROON IRAQ SPAIN CANADA ISRAEL SUDAN CEYLON ITALY SWEDEN CHILE IVORY COAST SWITZERLAND CHINA JAMAICA SYRIA COLOMBIA JAPAN THAILAND CONGO, DEMOCRATIC KENYA TUNISIA REPUBLIC OF REPUBLIC OF KOREA TURKEY COSTA RICA KUWAIT UKRAINIAN SOVIET SOCIALIST CUBA LEBANON REPUBLIC CYPRUS LIBERIA UNION OF SOVIET SOCIALIST CZECHOSLOVAK SOCIALIST LIBYA REPUBLICS REPUBLIC LUXEMBOURG UNITED ARAB REPUBLIC DENMARK MADAGASCAR UNITED KINGDOM OF GREAT DOMINICAN REPUBLIC MALI BRITAIN AND NORTHERN ECUADOR MEXICO IRELAND EL SALVADOR MONACO UNITED STATES OF AMERICA ETHIOPIA MOROCCO URUGUAY FINLAND NETHERLANDS VENEZUELA FRANCE NEW ZEALAND VIET-NAM YUGOSLAVIA The Agency's Statute was approved on 23 October 1956 by the Conference on the Statute of the IAEA held at United Nations Headquarters, New York; it entered into force on 29 July 1957, The Headquarters of the Agency are situated in Vienna. Its principal objective is "to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the IAEA, 1966 Permission to reproduce or translate the information contained in this publication m aybe obtained by writing to the International Atomic Energy Agency, KSrntner Ring 11, Vienna 1, Austria. Printed by the IAEA in Austria May 1966

5 SAFETY SERIES No. 18 ENVIRONMENTAL MONITORING IN EMERGENCY SITUATIONS A MANUAL BASED ON THE WORK OF A PANEL OF EXPER T S INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1966

6 In te rn a tio n a l A to m ic E n e r g y A g en cy. E n v iro n m e n ta l m o n ito rin g in e m e rg e n c y s itu a tio n s. A m an u al b ased on the w ork of a p anel of e x p e r ts. V ien n a, th e A gen cy, p. (IA E A, S afety s e r i e s no. 18) THIS MANUAL IS ALSO PUBLISHED IN FR EN C H, RUSSIAN AND SPANISH ENVIRO NM ENTAL MONITORING IN EM ER G EN C Y SITUATIONS IA EA, VIENNA, 1966 STI/PUB/118

7 FOREWORD Should an accid en t leading to the uncontrolled re le a se of rad io activ e su b stan ces to the n atu ral environm ent o ccu r, it is m ost im p ortant that an adequate m onitoring sy stem be put into operation as quickly a s p o ssib le. In such a s y ste m the le v e ls of rad iatio n and the le v e ls of rad io activ e con tam inan ts to which the public m ight be exposed should be m easu red and one of its m ain p urposes would be to provide tim ely data on which to base any n e ce ssa ry p rotective and rem ed ial actions. This manual gives tech n ical guidance on appropriate em ergency m onitoring p roced ures to those who would have to a sse ss the situation a f te r su ch an a ccid e n t. It d oes not set out to p rovid e e m e rg e n cy plans applicable to a ll situations, but ra th e r to draw attention to the im portant fa cto rs which should be considered in form ulating specific plans. It was p rep ared with the help of an international panel co m prising exp erts recom m ended by M ember States and rep resen tatives of o th er in tern atio n al o rg an izatio n s. W hile the publication should be of in terest and use to all countries, it is hoped that it will be p articu larly helpful to the developing ones.

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9 CONTENTS LIST O F P A N E L M EM BERS INTRODUCTION A im s of the m anual S c o p e O B JE C T IV E S OF EM ER G EN C Y ENVIRONMENTAL MONITORING To determ ine whether an abnorm al re le a se of rad io active m a te ria ls has o ccu rred To determ ine rapidly whether the re le a se of rad io active m a te ria ls is of such a type and extent that action m ust be taken to p ro tect the health and p rop erty of the public To provide inform ation on which subsequent rem ed ial m e a su re s m ay be b a s e d NATURE O F, AND HAZARDS RESULTING FROM, ACCIDENTAL R E L E A S E S O F RADIOACTIVE M ATERIALS TO THE ENVIRONS Types of fa cilitie s and th eir in ven tories T ypes of fa cilitie s In ven tories of rad io active m a te ria ls Types of accid en ts and a sso ciated re le a se of rad io activ e m a te ria ls O verheating of irrad iated fuel elem ents F ir e resu ltin g in d isp ersal of the radionuclides to the environm ent R elease of radionuclides from explosive accid en t N aturally caused accid en ts N u clear excu rsio n P h y sical lo ss of a radiation sou rce Rupture of con tain er

10 3.3. D isp ersal of released m a te ria l in the environm ent and possible m odes of exp osure of p erson s D isp ersal in the atm osphere D isp ersal in su rface w aters D isp ersal in the sea D isp ersal in the soil THE EM ER G EN C Y MONITORING PROGRAMME Form u lation of an ap propriate m onitoring p rogram m e P re lim in a ry inform ation required G eneral con sid erations The need fo r p re -e m e rg e n cy su rveys Initial detection and assessm en t of accid en tal re le a se O rganization and staffing O rganization S ta ffin g EM ER G EN C Y MONITORING PRO CEDURES E n viron m en tal m onitoring used as a detection sy stem The in itial su rv ey A ssessm en t of air-b orn e contam ination Rapid a sse ssm e n t of the a re a affected E xam in ation of w ater and food Subsequent su rv ey s R e a sse ssm e n t of in itial m easu res Follow ing the trend of contam ination M easu rem en t of in tern al doses C ollection of scien tific data EM ER G EN C Y MONITORING EQ U IPM EN T In stru m en ts fo r detecting an abnorm al re le a se of rad io activ e m a te ria ls In stru m en ts for asse ssin g radiation and contam ination levels in the field P o rtab le su rvey in strum ents N on-portable survey instrum ents... 46

11 6.3. Equipm ent fo r collectin g sam ples and instrum ents fo r a ssessin g th eir rad ioactive contam ination Sampling M easuring instrum ents M iscellaneous equipment. s T ran sp o rt equipment Com m unications and warning equipment., M eteorological equipment P ro te ctiv e equipment W arning and con trol equipment INTRODUCTION TO ANNEXES ANNEX I INVENTORIES OF FISSION-PRODUCTS AND PO SSIBLE R ELEA S ES ANNEX II AIR-BO RN E R EL E A S E S: DISPERSION, DEPOSITION AND D O SE-EXPO SURE RELATIONSHIPS ANNEX III A L P H A -, B E T A - AND GAMMA-RADIATION SURVEYS ANNEX IV SA M PLE CO LLEC TIO N AND FIELD EVALUATION ANNEX V SPE C IA L AN ALYTICAL CONSIDERATIONS.. 91 ANNEX VI INSTRUMENTATION AND EQUIPM ENT ANNEX VII ENVIRONMENTAL MONITORING PRO CEDURES ADOPTED IN PREVIOUS EM ER G EN C Y SITUATIONS R E FE R E N C E S BIBLIOGRAPHY

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13 LIST OF PANEL MEMBERS Panel on E nvironm ental M onitoring in E m ergency Situations C h a ir m a n K. A. M ahmoud M e m b e r s A. A ark ro g E. Fenyves R.J. G arn er A. R. Keene D. M echali H. W atanabe P rotection D epartm ent, A tom ic E nergy E stab lish m en t, C airo, United A rab Republic D anish A tom ic E nergy C om m ission, R e se a rc h E stab lish m en t Ris0, Roskilde, D enm ark C entral R e se a rc h Institute fo r P h y sics, B udapest, H ungary United Kingdom A tom ic E nergy A uthority, A uthority H ealth and Safety B ranch, Harwell^ B e rk s., United Kingdom B atelle-n orthw est, Richland, W ash., United States of A m erica C entre d 'etudes n u cle aires de Fontenay-aux-R os e s, F ran ce N ational In stitu te of Radiological Sciences, Chiba, Japan 1

14 Observ ers \ S. H alter (Consultant) E. Hampe L.E. L a rsso n E. W allauschek G. W ortley W orld H ealth O rganization (P resent address: D ire c te u r g en eral de l'a d m in istra - tion de l'hygidne publique, M inists re de la sante publique et de la fam ille, B ru ssels, Belgium ) E uropean A tom ic E nergy Com m unity (EURATOM), P a r is, F ran ce F o rm e rly R adiation and Isotopes, W orld H ealth O rganization (P resen t address: In stitu te of R adiophysics, Stockholm, Sweden) O rganisation fo r Econom ic C o-operation and Developm ent/ E uropean N uclear E nergy Agency, P a r is, F ran ce F o rm e rly A tom ic E nergy B ranch, Food and A griculture O rganization (P resent address: Joint FAO/IAE A Division, Vienna) Scientific secretary G.E. Swindell D ivision of H ealth, Safety and W aste D isposal, In tern atio n al A tom ic E nergy Agency 2

15 1. INTRODUCTION A im s of the manual The p u rp o se of th is m anual is to provide advice and tech n ic a l guidance on m onitoring in connection w ith em erg en cy situ a tions resu ltin g fro m rad iatio n accid en ts involving the uncontr o lle d r e le a s e of ra d io a c tiv e s u b s ta n c e s to th e n a tu r a l e n v ir o n m e n t1. T h is g u id an ce is p ro v id e d fo r th o s e p e r s o n s, w hether m e m b ers of the staff of the estab lish m en t fro m which the re le a s e o rig in a te d o r of o th e r o rg a n iz a tio n s, w hose ta s k it is to a s s e s s the situ a tio n a r is in g a s th e r e s u lt of the a c c id e n t The m anual does not set out to provide an em ergency environm e n ta l m o n ito rin g plan a p p licab le to a ll situ a tio n s. R a th e r, it p ro v id e s g u id an ce on th e im p o rta n t f a c to r s w hich should be c o n sid e re d in fo rm u la tin g sp ecific em e rg e n c y m o n ito rin g p la n s. F u r th e r m o r e, th e te c h n iq u e s and p ro c e d u r e s d e s c rib ed in both the m ain tex t and the A nnexes should be co n s id e r e d a s e x a m p le s only. T h e ir a p p lic a b ility to s p e c ific c ir c u m s ta n c e s w ill v a r y w idely W hile it is hoped th a t the m anual w ill be of help to c o u n trie s in a ll sta g e s of developm ent, p a rtic u la r atten tio n is given to the sp ecial needs of the developing co u n tries Scope The em e rg e n c y en v iro n m en ta l m o n ito rin g r e f e r r e d to in th is m anual is concerned with the m easu rem en t of lev els of ra d ia tio n and le v e ls of ra d io a c tiv e c o n ta m in a n ts in fo o d stu ffs, w a te r, a i r and o th e r m e d ia of in t e r e s t, to w hich m e m b e rs o f th e p u b lic could be e x p o se d a s th e r e s u lt of an a c c id e n t o c c u r r in g d u rin g th e o p e ra tio n, h a n d lin g, o r tr a n s p o r t of s o u r c e s of io n iz in g ra d ia tio n. It is n o t w ith in th e sco p e of the m a n u a l to a tte m p t to e s ta b lis h ra d ia tio n d o se s o r le v e ls 1 T h e m onitoring o f persons is not d ealt with exten siv ely as that to p ic is considered in greater detail in other publications, for exam ple: International Atom ic Energy Agency, Assessment of Radioactivity in M an, 2 vols, IAEA, Vienna (1964). 3

16 of contam ination in a ir, w ater, etc. w hich would be c o n sid e re d a c c e p ta b le to m e m b e rs of the public u n d e r e m e rg e n c y co n d itio n s C onsideration is given to the p o ssib le re le a s e s and subsequent d is p e r s a l of ra d io a c tiv e co n ta m in a tio n re s u ltin g fro m a c c i dents to n u c le a r re a c to rs, p ro c e ssin g fa c ilitie s, la b o ra to rie s, liq u id w a ste s to ra g e f a c ilitie s and ship p ing c o n ta in e rs, and to the fo re s e e a b le ra d ia tio n and co n ta m in a tio n le v e ls in the su rro u n d in g a r e a s An outline is given of the re q u ire m e n ts of ad eq u ate e n v iro n m e n ta l m o n ito rin g fo r th e d e te c tio n of any e m e rg e n c y s i t uation, the d em a rcatio n of affected a re a s and the a sse ssm e n t of th e n a tu re, e x te n t and sig n ific a n c e of the c o n ta m in a tio n in o rd e r to p ro v id e tim e ly d ata on w hich a p p ro p ria te p ro te c tive and rem ed ia l actions could be based. P a rtic u la r atte n tion is given to the tim ing and re la tiv e p rio ritie s of the actions to be taken It is anticipated that the period during which th is m anual would be m o st u se fu l is th e v ita l p e rio d im m e d ia te ly follow ing an accident when action needs to be rapid and decisive and th e re fore, as fa r as possible, planned in advance. 4

17 2. OBJECTIV ES OF EM ERGENCY ENVIRONMENTAL MONITORING To d e te r m in e w h e th e r an a b n o rm a l r e le a s e o f r a d io a c tiv e m a te r ia ls h a s o c c u r r e d The d etectio n of an ab n o rm al re le a s e of rad io activ e m a te ria l by a sy ste m w hich w ill give e a rly w arning is a p re -re q u is ite fo r the initiation of ap p ro p riate em ergency action. It is u su a lly m o re s a tis f a c to r y to m ake p ro v is io n fo r th e d e te c tio n of the r e le a s e at the s o u rc e r a th e r th a n in the e n v iro n m e n t, but in s p e c ia l c irc u m s ta n c e s p a rt of a continuously o p eratin g e n v iro n m e n ta l m o n ito rin g s y s te m m a y be u sed to d e te c t an abnorm al re le a se. The in itial indications of the w arning sy s te m m u st be follow ed ra p id ly by s p e c ia l e m e rg e n c y in v e s tig a tio n s a im e d at co n firm in g that an a b n o rm a l re le a s e to the e n v iro n s h as in fa c t o c c u rre d T o d e te r m in e r a p id ly w h e th e r th e r e l e a s e o f r a d io a c tiv e m a te r ia ls i s o f su ch a ty p e and e x te n t th a t a c tio n m u s t be ta k e n to p r o t e c t th e h e a lth and p r o p e r t y o f th e p u b lic A rap id in itia l su rv ey of the a re a s w hich m ay be contam inated is req u ired to a s s is t in deciding what action, if any, is necessa ry in o rd e r to safeguard the health of the public and to p ro te c t liv e sto c k, fo o d sto re s and o th e r p ro p e rty. Such p ro te c tiv e a c tio n m ig h t in c lu d e th e im p o s itio n of r e s t r i c t i o n s on the consum ption of w ater, specified c ro p s, including c e re a ls, and o th e r fo o d stu ffs and m ilk p ro d uced w ithin d e sig n a te d r e g io n s, the e v a c u a tio n of the p o pulatio n in d e sig n a te d a r e a s, th e tr a n s f e r of liv e s to c k o r food to c o v e re d p r e m is e s, and the u se of a lte rn a tiv e food su p p lies fo r liv e sto c k. A s fa r as p o ssib le the s u rv e y should be planned to p ro v id e the n e c e s s a ry inform ation w ithin a few h ours a fte r the accident To provide information on which subsequent r e m e d i a l m e a s u r e s m a y b e b a s e d S urveys need to be continued to provide adequate info rm atio n on the developm ent of the situ atio n on which to b ase d ecisio n s concerning the extension o r rem o val of in itially im posed re - 5

18 s tr ic tio n s and th e ap p lic a tio n of re m e d ia l m e a s u r e s. T hey sh ould be co n tin u ed u n til the e n v iro n m e n ta l situ a tio n is s ta b le o r its changing statu s is known and under control. Such s u r v ey s a lso fo rm a b a sis fo r the a s s e s sm e n t of the d o se s w hich m ay be receiv ed by m em bers of the public and m ay also p ro vide inform ation of scientific in te re st on the passage of rad io active nuclides through the n atural environm ent. 6

19 3. NATURE OF, AND HAZARDS RESULTING FROM, ACCIDENTAL RELEASES OF RADIOACTIVE MATERIALS TO THE ENVIRONS Im p o rta n t c o n s id e ra tio n s w hich should be ta k e n into account in planning an e n v iro n m e n ta l m o n ito rin g p ro g ra m m e th a t is ad eq u ate u n d er em erg en cy conditions include: (a) The types of rad io n u clid es involved; (b) T he q u a n titie s of ra d io n u c lid e s p re s e n t; (c) The lo c atio n of the fa c ility in re la tio n to population c e n tre s and th e ir com positions and d ensities, surface w aters, oceans, tra n s p ortation c e n tre s and highw ays e tc., taking into account m e te o ro lo g ic a l, h y d ro lo g ic a l and o th e r n a tu r a l c o n d itio n s w hich m ig h t in flu e n c e the d is p e r s a l of re le a s e d ra d io n u c lid e s ; (d) T h e q u a n titie s o f ra d io n u c lid e s w hich m ig h t be r e le a s e d and t h e ir p o s s ib le r a t e s of r e le a s e ; (e) T he d is p e r s a l ro u te and su b se q u e n t p athw ays th ro u g h the b io s p h e re le a d in g to hum an e x p o su re ; (f) T he d is ta n c e s and a r e a s o v e r w hich th e ra d io n u c lid e s m ay be d is p e rs e d ; (g) T he p e rs is te n c e of im p o rta n t q u a n titie s of the r e le a s e d ra d io n u c lid e s in the e n v iro n m e n t. T he sp e c ific m e c h a n ism by w hich an a c c id e n t is b ro u ght about is of only ind irect im portance in the planning of an adequate environm ental m onitoring program m e T yp es o f f a c ilitie s and th e ir in v e n to rie s Types of facilities F a c ilitie s su ch a s th o se involving th e o p e ra tio n of r e a c to r s, the p ro c e s s in g of irra d ia te d fu e ls, the s to ra g e of ra d io a c tiv e w a s te s, th e p ro d u c tio n of ra d io is o to p e s an d la b e lle d c o m pounds, the co n d uct of la b o r a to ry r e s e a r c h, the u se of i s o to p e s ( e.g. in h o s p ita ls ), an d th e s h ip m e n t of r a d io a c tiv e m a te r ia ls m ay have f e a tu re s w hich a r e su ffic ie n tly d iffe re n t to in flu e n c e th e r e la tiv e im p o rta n c e of th e f i r s t t h r e e c o n s id e r a tio n s lis te d in the p re v io u s se c tio n. T h e se d if fe r e n c e s m u s t be re c o g n iz e d if e m e rg e n c y m o n ito rin g p r o c e d u r e s a r e to be p r a c tic a l and e ffe c tiv e. 7

20 Inventories of radioactive m aterials T he q u a n titie s and ty p e s of ra d io n u c lid e s w hich a r e p r o c e s s e d, h an d led o r s to r e d in a fa c ility, th e ir p h y s ic a l and c h e m ic a l fo rm s and the n a tu re of th e ir co n ta in m e n t, a re of p r i m a ry im p o rtan ce in the p red ictio n of the m agnitude and extent of an accid en t involving the en v iro n s. The q u an tities involved ra n g e fro m m ic ro c u rie s to m e g a c u rie s. The ty p es of ra d io n u c lid e s ra n g e fro m re la tiv e ly innocuous n u c lid e s w ith sh o rt h a lf-liv e s and little o r no uptake by the body to long h a lf-life b o n e -s e e k e rs. The d iffe re n c e s in the in v e n to rie s of v a rio u s ty p e s of f a c ilitie s a r e illu s tr a te d by th e follow ing re v ie w of s e v e r a l m a jo r c a te g o rie s of f a c ilitie s : (a) R e a c to r s W hile the ty p e s of r e a c to r s a r e f a r too v a rie d to e n u m e ra te in th is m anual, it can be sta te d th a t a c h a ra c te r is tic of m any r e a c to r s i s th a t th e y c o n ta in re la tiv e ly la r g e a m o u n ts of f is s io n - p r o d u c ts. T he d e fin itiv e e s tim a tio n of sp e c ific in v e n to rie s r e q u ir e s know ledge of su ch p a r a m e te r s a s : (i) T he type of r e a c to r ; (ii) The pow er level; (iii) T he fu e l u se d ; (iv) T he o p e ra tin g h is to ry of the fu e l in th e r e a c to r. S ince th e s e p a r a m e te r s v a r y w idely, and to a la r g e e x te n t independently, only exam ples of quantitative d ata can be in clu d e d in th is m a n u a l2. E x a m p le s of su ch q u a n titie s of s e le c te d f is s io n - p r o d u c ts fo r a u ra n iu m -fu e lle d r e a c to r a r e included in T able I. 1 of Annex I. T h ese ta b le s obviously can o n ly s e rv e a s a g e n e ra l guide. W hile it is not p a r tic u la r ly ussetul to a tte m p t to ra n k the ty p e s of f a c ilitie s a c c o rd in g to p o te n tia l ris k, it can be said that th e re a r e v e ry few, if any, r e a c to r s w hich w ould not r e q u ire an a s s o c ia te d e m e rg e n c y e n v iro n m e n ta l p lan. 2 For planning en v iro n m en tal m o n ito rin g, it is only n ecessary to ap p roxim ate th e m agnitude of the inventory. The accuracy of estim ates of inventory which is required for the planning of em ergency monitoring is not necessarily the same as that required in formal hazard analyses.

21 (b) P r o c e s s in g f a c ilitie s F a c ilitie s p ro c e s s in g ir r a d ia te d o r sp en t fu el e le m e n ts a lso co n stitu te, in g e n e ra l, a c a te g o ry of fa c ilitie s w hich re q u ire planning fo r e m erg en cy e n v iro n m en ta l situ atio n s in the event of an accident. The quantities of m ate rials involved w ill usua lly be s u b s ta n tia lly le s s th a n the ra d io n u c lid e in v e n to ry in a la rg e re a c to r. M oreo ver, the p ro p o rtio n s in w hich ra d io active nuclides are present in processing plants also are lik e ly to be quite d iffe re n t fro m th o se in w hich they a r e p re s e n t in a re a c to r since, at the tim e of p ro cessin g o r re p ro c e ssin g, the inventory of sh o rt-liv e d nuclides w ill o rd in a rily constitute a m uch s m a lle r fra c tio n of the to ta l inven to ry. An additional d if fe re n c e w h ic h in flu e n c e s th e e n v ir o n m e n ta l m o n ito rin g p la n n in g i s th e fa c t th a t a t s p e c ific s te p s in th e p ro c e s s in g o p e ra tio n, th e n u c lid e c o m p o s itio n m a y be lim ite d to only a few ra d io n u c lid e s w hich m ay be p a r tic u la r ly h a z a rd o u s o n es su ch a s p lu to n iu m o r s tro n tiu m and, th e r e f o r e, d e te c tio n in th e e n v iro n s m ay n o t be a s e a s ily o r s im p ly a c co m p lish ed a s in the o rd in a ry m ixed fissio n -p ro d u c t r e le a s e fro m a r e a c to r. (c) Isotope production plants It is n o t fru itf u l o r f e a s ib le to a tte m p t to g e n e r a liz e on the n a tu re, m agnitude and sig n ifican ce of the inven to ry of isotope p ro d u c tio n p la n ts. It is c l e a r th a t the p o te n tia l s e v e r ity of a n a c c id e n ta l r e l e a s e f r o m a p la n t p ro d u c in g 32P, f o r e x am ple, is su b sta n tia lly d iffe re n t fro m th a t of a r e le a s e fro m a plant sep aratin g and producing 89Sr, 90Sr o r 238Pu. A few p o in ts a r e p e rh a p s w o rthy of b r ie f m e n tio n. U su ally su c h p la n ts w ould h av e an in v e n to ry s u b s ta n tia lly s m a lle r ( e.g. by a fa c to r of 106 o r m o re ) th a n th a t of a p r o c e s s in g plant o r re a c to r. E ven m o re so than in the case of a p ro c e s sing plant, the iso to p e producing plant is lik ely to have w e llsep arated radionuclides which could m arkedly affect the p ro c e d u re s and in s tru m e n ta tio n w hich would be em ployed in the e m e rg e n c y e n v iro n m e n ta l m o n ito rin g. 9

22 (d) O th e r la b o r a to rie s T h is c a te g o ry in c lu d e s a w ide v a r ie ty of fa c ilitie s ra n g in g fro m v e ry s m a ll h ig h ly s p e c ia liz e d la b o r a to r ie s w ith r e l a tiv e ly s m a ll in v e n to rie s of ra d io n u c lid e s to la r g e m u ltip u rp o se la b o r a to r ie s co n d uctin g a w ide v a rie ty of r e s e a r c h p r o je c ts an d w ith a re la tiv e ly la rg e in v e n to ry of m a n y d iff e r e n t r a d io n u c lid e s. M any of th e f a c to r s w h ich in flu e n c e e n v iro n m e n ta l m o n ito rin g u n d e r e m e rg e n c y c o n d itio n s fo r la b o r a to r i e s a r e s im i la r to th o s e in v o lv ed in iso to p e p r o ducing p la n ts. The sp ecific q u antities and types of m a te ria ls b e in g h a n d le d an d th e n a tu r e of th e s ite w ill la r g e ly sh a p e th e ty p e an d e x te n t of e m e rg e n c y p la n s. (e) W a ste s to r a g e f a c ilitie s M any of th e fa c ilitie s d e s c rib e d ab o v e w ill have a s s o c ia te d facilities for the storage of liquid o r solid radioactive w astes u su a lly fis s io n -p ro d u c ts. L iquid w a ste s to ra g e f a c ilitie s may range 'in size and com plexity from m odest ordinary s to r age tanks w ith re lativ ely sm all in v en to ries to v ery larg e und e rg ro u n d v e s s e ls em p lo y in g co o lin g e q u ip m e n t to re m o v e e x c e s s iv e h eat re s u ltin g fro m ra d io a c tiv e d ecay. T he m o st p ro b a b le m o d e of r e l e a s e to th e e n v iro n m e n t fro m liq u id w aste s to ra g e fa c ilitie s is by lo s s of in te g rity of the sto ra g e v e s s e l p e rm ittin g som e lo s s of liq u id to the ground and p o s sib ly g ro u n d -w a te r. L o ss of coolin g could c a u s e e x p lo siv e boiling in h ig h -lev el w aste sto rag e tanks and subsequent r e le a s e s to the a tm o s p h e re. W aste d is p o s a l f a c ilitie s w hich a r e u se d fo r so lid c o n ta m i n a te d ite m s, e. g. a n a ly tic a l la b o r a to r y w a s te s, d e fe c tiv e s m a ll to o ls an d e q u ip m e n t an d r a g s, o fte n c o n s is t o f o pen tr e n c h e s in th e g ro u n d w hich a r e b a c k fille d a f te r d is p o s a l. T h is ty p e of fa c ility m ay o c c a s io n a lly a c c id e ta lly r e le a s e s m a ll a m o u n ts of ra d io n u c lid e s to th e e n v iro n s a s a r e s u lt of sp o n ta n e o u s c o m b u stio n o r g ro u n d -w a te r le a c h in g of the tre n c h. H ow ever, su ch d is p o s a l s ite s a r e u su a lly c o n sid e re d to be a v e r y m in o r s o u r c e of a c c id e n ta l r e l e a s e to th e e n v iro n m e n t.

23 (f) T ra n sp o rt co n tain ers T hese so u rces a re m entioned because of the in creasin g ship - - m ents of rad io activ e m a te ria ls betw een c e n tre s by a ir, w ater, ro a d o r r a i l. A lthough the h a z a rd s fro m a c c id e n ts involving th e se m odes of tra n s p o rt m ay be v e ry d ifferen t, the com m on c h a ra c te r is tic is the m obility of the source-. T his c h a r a c te r is tic n e c e s s ita te s a high d eg ree of flexibility in en vironm ental m o n ito rin g. F a c to rs w hich fa c ilita te effectiv e en v iro n m en ta l m onitoring in the event of an accident include: (i) A re a s o n a b ly a c c u r a te know ledge of th e ty p e, q u a n tity and p h y s ic a l s ta te of m a te r ia ls involv ed ; (ii) Som e option w ith re g a rd to the lo c a tio n of the c o n ta in e r in re la tio n to its environm ent in o th e r w ords, the ro u te and tim in g of th e sh ip m e n t w hich could in flu e n c e th e p o te n tia l d e m a n d s on e n v iro n m e n ta l m o n ito rin g in th e e v e n t of an a c c id e n t. F a c to rs w hich h am p er the planning and c a rry in g out of e m e r gency m onitoring in the event of an accident involving a sh ip ping co n tain er include: (i) T he highly v a ria b le lo c atio n of the c o n ta in e r in re la tio n to i t s e n v iro n m e n t w h ich could n e c e s s ita te g r e a t sp e e d an d l a s t m in u te c h a n g e s in th e e m e rg e n c y m o n ito rin g p r o c e d u r e s ; (ii) The likelihood of the contam inants fro m an accident being f u r th e r d is p e rs e d s e c o n d a rily by tra n s p o rta tio n e q u ip m e n t b e fo re c o n tr o l a t th e s ite of th e a c c id e n t c a n be a c h ie v e d ; (iii) L ack of e x p e rie n c e d a id w ithin o p e ra tin g d is ta n c e of an a c c id e n t, w hich could th e o r e tic a lly o c c u r on highw ays, ra ilw a y s o r w a te r-w a y s o r at any point on land u n d e r the w orld a ir ro u te s Types of accidents and associated release of radioactive materials A v e ry long lis t of the ty p e s of ra d ia tio n a c c id e n ts w hich can o c c u r and w hich c o u ld r e s u lt in r e le a s e of ra d io n u c lid e s to th e e n v iro n m e n t could be fo rm u la te d. M any su ch a c c id e n ts w ould involv e c lo s e ly re la te d f a c to r s fo r th e p lannin g of e m e rg e n c y m o n ito rin g p r o g r a m m e s. T h e l i s t of ty p e s of 11

24 a c c id e n ts b rie fly d is c u s s e d in the n ex t few p a g e s is n o t in ten d e d to be c o m p re h e n siv e ; r a th e r, it s u g g e sts th e w idely d ifferin g ty p es of ev en ts w hich can cau se a c c id e n ta l re le a s e s of ra d io n u c lid e s. A b r ie f d is c u s s io n of the m o re im p o rta n t f a c to r s w hich a r e p e rtin e n t to e n v iro n m e n ta l m o n ito rin g is included fo r each acc id en t type liste d Overheating of irradiated fuel elem ents D u rin g o p e ra tio n of a n u c le a r r e a c to r, la r g e q u a n titie s of ra d io a c tiv e m a te r ia ls a c c u m u la te w ith in th e fu e l. T he a b s o lu te and r e la tiv e q u a n titie s of th e s e r a d io n u c lid e s in th e c o re of the r e a c to r a r e d ep en d en t on s e v e r a l r e a c to r o p e r atin g p a r a m e te r s in clu d in g the type of re a c to r, typ e of fuel, e x te n t of ir r a d ia tio n, p o w e r le v e l of th e r e a c to r, an d th e le n g th of tim e b etw een r e a c to r sh u t-d o w n and th e a c c id e n t. The m o st im p o rta n t fis sio n -p ro d u c t in the a c c id e n ta l r e le a s e fro m a r e a c to r w ill v e r y lik e ly be 131I. T he e ffe c ts of the r e le a s e s of o th e r fis s io n -p ro d u c ts can n o t be ig n o re d, how e v e r. Included am ong th e se o th e r n u c lid e s a r e : o th e r i s o to p e s of io d in e, iso to p e s of te llu riu m, s tro n tiu m, c a e siu m, ceriu m, ruthenium, and the r a r e g ases, krypton and xenon. Two im p o rta n t fa c to rs affecting the en v iro n m en ta l m onitoring follow ing a r e a c to r a c c id e n t a r e th e v o la tility of the fis sio n - p ro d u c ts c o n c e rn e d, and the s ta tu s of the r e a c to r in re s p e c t of its s ta r t- u p tim e, o p e ra tin g h isto ry, and shut-dow n tim e. An accid e n t o c c u rrin g a fte r a r e a c to r h as been o p eratin g fo r only a few h o u rs a t a s u b s ta n tia l p o w er le v e l w ould involv e only sh o rt-liv ed isotopes in im portant am ounts. The quantit ie s of s tro n tiu m, c a e s iu m, ru th e n iu m, and c e r iu m w ould be n e g lig ib le. If an a c c id e n t w e re to o c c u r w ithin a few day s a f te r s ta rtin g th e o p e ra tio n of a r e a c to r a t a s ig n ific a n t p o w e r le v e l, th e iodine iso to p e s w ould have la rg e ly a ttain ed e q u ilib riu m w hile th e q u a n titie s of lo n g -liv e d iso to p e s, su ch a s s tro n tiu m and c a e siu m,w o u ld s ti l l be n e g lig ib le. If th e r e a c to r h ad b e e n o p e ra tin g fo r a s u b s ta n tia l p e rio d of tim e and had b een shut down fo r a p erio d, fo r exam ple, of two m onths o r m o re, a ll of the s h o rt-liv e d iso to p e s such a s iodine would have decayed to negligible quantities. A re a c to r accident under these c ir - 12

25 cu m sta n c e s would have its m a jo r effects in the environ s fro m the r e le a s e s of i37cs and 90S r since th e se n u clid es would not have decayed appreciably during the shut-dow n period. A u sefu l sim p lific a tio n in planning em e rg e n c y e n v iro n m en ta l m o n ito rin g in th e ev en t of a r e a c to r a c c id e n t is to c o n s id e r 1311 as the m ost dem anding radionuclide in re g a rd to the speed w ith w hich m e a s u re m e n ts m u st be m ade and s a m p le s m u st be collected. The program m e, of course, m ust be sufficiently c o m p re h e n s iv e to a s s e s s th e sig n ific a n c e of a ll th e i m p o rta n t co n ta m in an ts w hich m ay be re le a s e d to the e n v iro n s. D ata a re given in Annex I, T ables I. 2 and I. 3. In spite of the fa irly definitive inform ation w hich can be co l le c te d re g a rd in g the in v e n to rie s of ra d io a c tiv e m a te r ia l in r e a c to r c o r e s fo r d iffe re n t ty p e s of r e a c to r s in r e s p e c t of different operating h isto rie s, th ere a re m any im portant fact o r s w hich in flu e n c e th e q u a n titie s and r a tio s of th o s e m a t e r i a l s w hich m ay c o n ta m in a te th e e n v iro n s in th e ev en t of an a c c id e n t. In clu d e d a r e su c h th in g s a s p r e f e r e n tia l r e le a s e s of the m o re v o la tile com ponents and the effe c tiv e n e ss of building containm ent and filte rin g s y ste m s. It should also be c le a rly re c o g n iz e d th a t even in the c a s e of a r e a c to r fu el a c c id e n t, w h ere a h a z a rd s a n a ly sis e s tim a tio n tra d itio n a lly h a s b een m o re th o ro u g h ly tr e a te d th a n h a z a rd s a n a ly s is in o th e r ty p e s of fa c ilitie s, th e p o stu la te d r e l e a s e s a r e only e s tim a te s of th e c o n s e q u e n c e s of th e p o stu la te d a c c id e n ts. At b est, they p ro v id e an o rd e r of m agnitude in d icatio n of the e x te n t of e m e rg e n c y e n v iro n m e n ta l m o n ito rin g w hich m ight be re q u ire d in the event of an accident. In th e c a s e of a r e a c t o r a c c id e n t, th e m o s t lik e ly ro u te of d is p e r s a l of im p o rta n t a m o u n ts of ra d io n u c lid e s to th e e n v ir o n s is th e r e le a s e to th e a tm o s p h e re. E v en in th e c a s e of w a te r-c o o le d r e a c to r s, th e a tm o s p h e ric d is p e r s a l ro u te is m uch m o re lik e ly to c o n stitu te the m o st dem anding b a s is fo r planning, ra th e r than the re le a s e of rad io n u clid es to s u r face w a te r-w a y s. A le s s lik ely m ode of d is p e rs a l in the s ta tio n a ry r e a c to r, fu e l o v e rh e a tin g o r p a r tia l m e lt-d o w n a c cident, is the re le a s e of rad io n u clid es to the ground. M ore com prehensive planning is req u ired fo r em ergency env ironm en tal m onitoring following a re a c to r accident than for 13

26 the o th e r types of accid en ts d isc u sse d below. T his d ifference r e s u lts fro m the c o m b in atio n of a la rg e f is s io n -p ro d u c t in v en to ry in the r e a c to r and the high p ro b ab ility of atm o sp h eric d is p e r s a l. A s e rio u s r e a c to r a c c id e n t is m o re lik ely to r e s u lt in w id e sp re a d co n ta m in a tio n of th e e n v iro n s th a n m o st o th e r ty p e s of n u c le a r a c c id e n ts. H ow ever, o th e r l e s s s e rio u s a c c id e n ts a r e m o re lik e ly to o c c u r. In s u m m a ry, th e lim itin g f a c to r s w hich in flu e n c e e n v ir o n m e n ta l m o n ito rin g fo r a r e a c to r a c c id e n t a r e th e d is p e r s a l ro u te to the a tm o s p h e re, and th e p re s e n c e of the r a d io is o to p e P lan n in g th a t is b a se d, in g e n e ra l, on th e se two p a r a m e te r s sh ould p ro v id e a d e q u a te p r e p a r e d n e s s in the c a s e of o th e r d is p e rs a l ro u te s and in v o lv em en ts w ith o th e r ra d io n u c lid e s. The en v iron m en tal m onitoring c a rrie d out follow ing the r e le a s e of fis s io n -p ro d u c ts to th e a tm o s p h e re fro m th e W indsc a le No. 1 P ile in O ctober 1957 an exam ple of an acc id en t in v o lv in g th e o v e rh e a tin g of a r e a c to r c o re i s d e s c rib e d in A nnex VII F ir e re su ltin g in d is p e rs a l of the rad io n u clid es to the environm ent T he m a jo r and probably the only im p o rta n t d is p e rs a l ro u te in the ev en t of f ire in conju n ction w ith an in v e n to ry of ra d io a c tiv e m a t e r i a l s i s th e r e l e a s e of im p o rta n t q u a n titie s of th e s e m a te r ia ls to the atm o sp h ere. It is likely that, except in the case of an esp ecially larg e and catastro p h ic fire, m ost of the conta m in a n ts r e le a s e d w ould be d e p o site d in th e v ic in ity of the a c c id e n t s ite. T he d e p o site d m a te r ia l m ay be m o re w idely d is p e rs e d a s d u st if co n d itions a r e fav o u rab le fo r re s u s p e n s io n (heavy tr a f f ic, w in d s, e t c. ) o r m a y be w ash ed in to s e w e r s o r p u b lic w a te r-w a y s b y h e a v y r a in o r w a te r u s e d to c o n tr o l th e f ir e R e le a s e of ra d io n u c lid e s fro m e x p lo siv e a c c id e n t 14 T he e n v iro n m e n ta l c o n seq u e n c es of an a c c id e n ta l r e le a s e of ra d io n u c lid e s follow ing v a rio u s ty p e s of e x p lo sio n s a r e not sufficiently d istin c t fro m the consequences of a fire to suggest the need for sp ecial planning for em ergency m onitoring. F o r

27 a c c id e n ts in v o lv in g c o m p a ra b le in v e n to rie s of m a te r ia ls it i s lik e ly th a t th e r e w ould be le s s c o n ta m in a tio n o f th e e n v ir o n s in th e c a s e o f an e x p lo sio n th a n in th e e v e n t of f i r e b e c a u se of lo w e r te m p e r a tu r e s in th e v ic in ity of the s o u rc e of ra d io a c tiv e m a te r ia ls N a tu ra lly c a u se d a c c id e n ts F a c ilitie s which a re located in g eograp h ical a re a s w here n a t u r a l phenom ena m ay d e s tro y the in te g rity of p ro te c tiv e c o n finem ent facilities should have environm ental em ergency p ro g ra m m e s w hich a r e e s p e c ia lly s u ita b le fo r d e a lin g w ith the consequences of such accid en ts. E xam ples of such phenom en a a r e tid a l w av es and e a rth q u a k e s. T h is c a te g o ry of a c c id e n ts cannot be p r e c is e ly defined but u n u su al o c c u rre n c e s s u c h a s r u p tu r e of u n d e rg ro u n d s to r a g e ta n k s an d r e l e a s e of t h e ir c o n te n ts in to th e g ro u n d, r u p tu re of u n d e rg ro u n d tra n s p o rt lin e s and s im ila r re le a s e of th e ir contents, w ashing of ra d io a c tiv e m a te r ia ls fro m s h o re -lo c a te d e s ta b lis h m e n ts into the s e a and flooding of n u c le a r e sta b lish m e n ts by inlan d w a te r-w a y s could a ll r e s u lt in u n usu al dem ands fo r effe ctiv e e m e rg e n c y m o n ito rin g. T h e m o s t u n u s u a l f e a tu r e o f 'th is ty p e of a c c id e n t is p ro b a b ly the r e le a s e of ra d io a c tiv e m a t e r i a l in to w a te r, e ith e r d ir e c tly, o r in d ir e c tly by r e l e a s e into the ground. W hile a ll m odes of d is p e rs a l to the en v iro n s a r e p o ssib le follow ing a n a tu ra lly c a u se d a ccid en t, the m o st lik ely d is p e rs a l ro u te s in the c a se of an earth q u ak e w ould be into the ground o r into the g ro u n d -w a te r, and in th e c a s e of tid a l w aves, the slu icin g of rad io nuclid es fro m s h o re -lo c a te d estab lish m en ts into the sea-w ater N uclear excursion W hile a n u c le a r e x cu rsio n m ay pose sev ere, o n -site problem s, it i s n o t lik e ly th a t s u c h an a c c id e n t w ould g iv e r i s e to an u rg e n t situ a tio n in the p u b lic e n v iro n m e n t. A ny r e le a s e of ra d io n u c lid e s fro m th e s ite w ould m o s t lik e ly be v ia the a tm o s p h e r e. T a b le 1.4, in A nnex I, l i s t s e x a m p le s o f r e le a s e s fro m p o stu la te d e x c u rsio n s of v a rio u s m a g n itu d e s. 15

28 Tlie n a tu re and e x ten t of the e n v iro n m e n ta l m o n ito rin g p e r fo rm e d follow ing the n u c le a r e x c u rsio n at the SL -1 R e a c to r, NRTS, Idaho, USA, a re d escrib ed in Annex VII P h y s ic a l lo s s of a ra d ia tio n so u rc e T h is type of a c c id e n t is not lik e ly to in v o lv e m any p e rs o n s in th e p u blic d o m ain, but b e c a u s e of th e u n c e rta in ty of the c irc u m s ta n c e s, th e re w ill be in te n se d em a n d s on the e m e r gency environm ental team to locate the source before ex cessive hum an exposure o ccu rs o r before the source is in ad v erten tly d estro y ed o r d isp e rsed, fo r exam ple, by burning. The d u ra tio n of the e m e rg e n c y m o n ito rin g p ro g ra m m e is lik e ly to be re la tiv e ly s h o r t. S e arch in g w ith su ita b le in s tru m e n ts, fo r p ra c tic a l r e a s o n s, w ill g e n e ra lly be lim ite d to lik ely lo c a tio n s w h ere the lo s s of c o n tro l could have o c c u rre d. The e x te n t of e n v iro n m e n ta l m o n ito rin g could expand s h a rp ly if the source should lose its physical integ rity thereby p e rm itting re le a s e and d is p e rs a l of the co n tam in an ts Rupture of container The rupture,by im pact, of a device or v essel containing rad io activ e m a te ria ls would in sta n tly change the n a tu re of c o n tro l and m o n ito rin g re q u ire m e n ts. The c o n tro l of se a le d o r co n tained so u rc e s principally involves controlling acc e ss of p e r so n s to the s o u rc e and c o n tro llin g m o v em en t of the s o u rc e. W hen the p h y s ic a l in te g rity of th e c o n ta in e r b a r r i e r i s im p a ir e d th e u n in te n tio n a l r e l e a s e of r a d io n u c lid e s to p u b lic a r e a s i s p o s s ib le. Such s itu a tio n s in v o lv in g e n v iro n m e n ta l m o n ito rin g c a n be d e s c rib e d in tw o e x a m p le s: C o llisio n o r im p a c t a c c id e n t at s e a o r on lan d. Such a c c id e n ts a r e fre q u e n tly accom p an ied by f ir e s. A re le a s e of rad io n u clid es fro m an im p act accid en t on lan d could ta k e m any f o rm s. R e le a s e of m a te r ia l s in to s u rfa c e w a te r, fo r ex am p le r i v e r s o r la k e s, w ould r e q u ire knowledge, gained by environm ental m onitoring, of the quantity and fa te of th e re le a s e d m a te r ia l s. S am p lin g of w a te r and aq u atic fo rm s would be re q u ire d u n til the extent and ra te o f m o v e m e n t of r e le a s e d m a te r i a l s th r o u g h th e b io s p h e r e w e re d e te r m in e d. 16

29 In th e c a s e w h e re im p a c t of v e h ic le s o r t r a i n s r e s u l te d in the ru p tu re of the s o u rc e c o n ta in e r, e n v iro n m e n ta l m o n ito r ing would m o st probably be re q u ire d in the im m ed iate vicinity of th e a c c id e n t. D is p e rs io n and r e d is tr ib u tio n by w e a th e r in flu e n c e s o r s c a tte rin g of any re le a s e d co n ta m in an ts by h u m a n o r v e h ic u la r tr a c k in g c o u ld q u ic k ly an d s u b s ta n tia lly a ffe c t th e am o u n t, lo c a tio n and ty p e of e n v iro n m e n ta l m o n ito rin g r e q u ir e d. R a d io a c tiv e m a te r ia ls a r e u su a lly tr a n s p o r te d in tw o ty p e s of packaging, one w hich w ould be d e stro y e d in a s e v e re a c cid en t' and the o th e r so ro b u st th a t it would w ithstand se v e re im p a c t and fire. In the fo rm e r type the ra d io a c tiv e co n te n ts a r e so lim ite d in quan tity th a t th e ir re le a s e w ould not c a u se significant hazard ; in the la tte r type the escape of the ra d io a c tiv e c o n te n ts, ev en u n d e r s e v e re a c c id e n t c o n d itio n s, is h ig h ly im p ro b a b le D i s p e r s a l o f r e l e a s e d m a te r ia l in th e e n v ir o n m e n t a n d p o s s i b l e m o d e s o f e x p o s u r e o f p e r s o n s A know ledge of the lik ely p a tte rn s of d is p e rs a l of ra d io a c tiv e m a te r ia l r e le a s e d to th e v a rio u s e n v iro n m e n ta l m e d ia c a n be of help in the p re d ic tio n of the ensuing m odes of e x p o su re of p e rs o n s and in d e c id in g on the n a tu re and u rg e n c y of th e e m e rg e n c y m o n ito rin g p r o c e d u re s w hich sh o u ld be u n d e r ta k e n. F o r c o n v e n ie n c e th e s e m e d ia a r e d is c u s s e d s e p a r a te ly but, of c o u rs e, m o re than one could be c o n ta m in a te d sim u ltan eo u sly. P a tte rn s of d is p e rs a l in the a tm o sp h ere and re la tio n s h ip s b etw een dose and le v e l of co n ta m in atio n of e n v iro n m e n ta l m e d ia a r e fu rth e r d is c u s s e d in A nnex II D is p e rs a l in the a tm o s p h e re R adioactive m a te ria ls could be re le a s e d to the atm o sp h e re in the fo rm of g a se s, a e ro s o ls o r v a p o u rs and th e ir su bseq u en t d is p e r s a l w ould be la rg e ly d e te rm in e d by th e p r o c e s s e s of tu rb u le n t diffusion in the a ir. The re le a s e d m a te ria l, in the f o r m of a clo u d, w ill g e n e r a lly m o v e d o w n -w in d f r o m th e p o in t of r e le a s e. M a te ria l in itia lly in the fo rm of a e r o s o ls o r v a p o u rs m ay be d ep o sited fro m the cloud on to the ground by s e d im e n ta tio n o r m a y be c a r r ie d dow n by r a in o r snow. 17

30 It is feasib le, by the application of th e o rie s concerning tu r b u le n t d iffu sio n and on th e b a s is of a n u m b e r of p la u s ib le assu m p tio n s, to p re d ic t the tim e -in te g ra l of the concentration of a ir-b o rn e rad io activ e m a te ria l, in c u rie -seco n d s p e r cubic m e tre, a t any poin t n e a r th e s u rfa c e of th e e a r th re s u ltin g fro m the p assin g cloud, and the su rface concentration of d e p o site d m a te r ia l a t p r e s c r ib e d d is ta n c e s fro m th e p o in t of r e le a s e. In A nnex II ty p ic a l c u rv e s a r e p re se n te d w hich in d icate the probable v ariatio n with distance of the tim e -in te g ra l of th e c o n c e n tra tio n fo r v a rio u s m e te o ro lo g ic a l c o n d itio n s. Such c u rv e s could be of a s s is ta n c e in the planning of the in itia l e m e rg e n c y s u rv e y s and in the s e le c tio n of m e a s u rin g te c h niques of adequate sen sitiv ity. A v a rie ty of m odes of ex p o su re of p e rso n s m ay be a sso c ia te d w ith a r e le a s e of ra d io a c tiv e g a s e s o r a e r o s o ls to th e a tm o s p h e re. T hey in clu d e: (a) W hole-body exposure to ex tern al radiation from the cloud; (b) W hole-body ex posure to e x te rn a l rad iatio n fro m m a te ria l deposited on the ground o r o ther su rfaces; (c) W h o le- o r p a rtia l- b o d y e x p o su re to e x te r n a l ra d ia tio n f ro m m a te r ia ls d e p o site d on th e sk in o r c lo th e s ; (d) E xposure to in tern al radiation following inhalation of a ir borne m a te ria l or disturbed deposited m aterial; (e) E xposure to in tern al rad iatio n following ingestion of contam inated food o r w ater. Some types of exposure m ay begin v ery soon a fte r the re le a se, fo r exam ple e x p o su re to e x te rn a l rad iatio n fro m the cloud o r in h a la tio n of a ir - b o r n e m a te r ia l; o th e r ty p e s m ay b eg in a t a l a t e r sta g e an d could p e r s i s t o v e r a long p e rio d of tim e, fo r e x a m p le th e in g e s tio n of d e p o site d m a te r ia l in i ts p r o g r e s s io n th ro u g h fo o d -c h a in p a th w a y s. Since rad io activ e m a te ria ls in hazard&u& concentrations m ay distances following a relea se to the a tm o sp h e re, e m e rg e n c y m o n ito rin g m ay be u rg e n tly r e q u ire d to d e te rm in e the c o n c e n tra tio n of a ir - b o r n e and d e p o sited m a te ria l o v e r a v e ry la rg e a re a. It should be re c o g nized, how ever, th a t the avoidance of hum an ex posure during th e p e rio d im m e d ia te ly fo llo w in g a su d d e n r e le a s e o v e r a s h o r t p e rio d of tim e is n o t f e a s ib le by m e a s u r e s b a s e d on e n v iro n m e n ta l m o n ito rin g. M onito rin g, h o w e v e r, m a y be

31 req u ired over an extended period of tim e to follow the m ovem ent of contam inants through food-chain pathw ays D is p e rs a l in su rfa c e w a te rs R a d io a c tiv e m a te r ia l could e n te r la k e s and r i v e r s d ir e c tly, fo r ex am p le a s liq u id w a s te s o r a s m a te r ia l d e p o site d fro m th e a tm o s p h e re, o r in d ir e c tly, f o r e x a m p le a s d e p o s ite d m a te ria l c a r r ie d by r a in -w a te r. The d is p e rs a l p a tte rn s and m e c h a n ism s, fo r ex am p le, diffu sio n of d isso lv e d m a te ria ls, su sp e n sio n of so lid s and ion-exchange w ith o th e r m edia, can in flu e n c e th e su b se q u e n t p athw ay of e x p o su re to m a n fro m m a te r ia ls r e le a s e d to s u rfa c e w a te r s. It m ay be a d v isa b le to m a k e a p r i o r stu d y of th o s e w a te r s in to w h ich la r g e a c c id e n ta l r e l e a s e s m ig h t o c c u r. T h e m o d e s of e x p o su re could in c lu d e : (a) E x p o su re to e x te rn a l ra d ia tio n follow ing im m e rs io n in, o r clo se ap p ro ach to, contam in ated w ater; (b) E xposure to in tern al rad iatio n following ingestion of contam inated w ater; (c) E x p o su re to in te rn a l ra d ia tio n follow ing the in g e stio n of contam inated fish o r w ater plants o r the ingestion of foodcrops irrig a ted by contam inated w ater; (d) E x p o su re to in te rn a l ra d ia tio n follow ing the consum ption of m ilk p ro d u c ed by cow s fed on p a s tu re s ir r ig a te d w ith contam inated w ate r. The m o st im p o rtan t mode of exposure in the period im m ed i a te ly follo w in g a r e l e a s e w ould be by th e in g e s tio n of c o n tam inated w ater. In an em ergency situation it would be n ece s s a r y to p ro v id e f o r v e r y e a r ly an d r a p id m o n ito rin g of p o ssib ly c o n ta m in a te d s u rfa c e w a te rs w h ich m ig h t be u sed fo r hum an consum ption D is p e r s a l in th e s e a R a d io a c tiv e m a te r ia l could e n te r th e s e a d ir e c tly, f o r e x a m p le, a s a r e s u lt of an a c c id e n ta l r e le a s e fro m an i n s t a l la tio n lo c a te d a t th e edge of the se a, a s a r e s u lt of s e v e r e d am a g e to a n u c le a r sh ip o r to a s h ip c a r r y in g ra d io a c tiv e m a te r ia ls, o r by d ep o sitio n fro m the a tm o sp h e re. T he m a 19

32 t e r i a l could a ls o e n t e r th e s e a in d ir e c tly th ro u g h a f r e s h w a te r p ath w a y. T h e o r e tic a lly, a p p lic a tio n of a p p ro p ria te d iffusion e q u a tio n s3 to g e th e r w ith p re lim in a ry stu d ie s of the a r e a m a y p e r m it p re d ic tio n of th e g e n e r a l p a tte r n of d is p e r s a l. In p r a c tic e, a s in the a tm o s p h e ric c a s e, r e lia n c e would have to be p laced on m e a su re m e n ts m ade subsequently to the accid en t. The p rincip al m odes of exposure include: (a) E x p o su re to e x te rn a l ra d ia tio n by im m e rs io n in the se a o r by clo se ap p ro ach to contam inated beaches o r handling of a rtic le s w hich have becom e contam inated w ith d etritu s, silt, etc. ; (b) E x p o s u re to in te r n a l ra d ia tio n by c o n su m p tio n of c o n ta m in a te d s e a -fo o d. The m ost im p o rtan t m ode of ex posure m ay be the consum p tio n of co n ta m in a te d se a -fo o d ; so m e m a rin e o rg a n is m s can c o n c e n tr a te c e r t a i n r a d io n u c lid e s by f a c to r s of The environm ental m onitoring req u ired following contam inatio n of s e a -w a te r is u su a lly not u rg e n t in n a tu re a s the co n su m p tio n of s e a -fo o d and e x p o su re to c o n ta m in a te d a r tic le s c an be re la tiv e ly e a s ily c o n tro lle d pending a d e ta ile d in v e s tigation of the d isp e rsa l of the contam inants. Prolonged m o n ito rin g m a y, h o w e v e r, be r e q u ir e d in o r d e r to t r a c e th e physical location of re le a se d long-lived contam inants in s e a w a te r an d t h e ir s u b s e q u e n t u p ta k e in m a r in e o r g a n is m s. T h e re w ould be a g r e a t e r d em and fo r e n v iro n m e n ta l m o n i to rin g follow ing a r e le a s e to c o a s ta l w a te r in re g io n s w h ere c u r r e n ts flow to w a rd s the land o r in re g io n s w h ere sea-fo o d is g a th e re d, fo r e x a m p le n e a r o y s te r b e d s, th a n follow ing a r e le a s e in to d eep w a te r D is p e r s a l in th e s o il R adioactive m a te ria l could be d is p e rse d in the su rface la y e rs of the so il following an accidental sp ill o r by deposition from into the S ea, 3 S e e, for exam p le. International A tom ic Energy A gen cy, R ad ioactive W aste Disposal Appendix V I, Safety Series No. 5, IAEA, Vienna (1961) 174 pp. 20

33 th e a tm o s p h e re. L iq u id ra d io a c tiv e m a te r ia ls r e le a s e d in the upper lay ers of perm eable soil could penetrate to the subso il; p a rtic u la te m a te r ia l d e p o site d on the su rfa c e could be c a r r ie d to the su b so il by ra in. R adio active m a te ria ls could also be released d irectly in the subsoil, for exam ple, following the ru p tu re of underground c o n ta in e rs o r p ip e -lin e s. The su b se q u e n t d is p e r s a l w ill be d e te rm in e d by the n a tu re of the subsoil and the extent and rate of m ovem ent of the u n derground w a te rs. The m odes of exposure include: (a) E x p o s u re to e x te r n a l ra d ia tio n fro m th e c o n ta m in a te d s o il; (b) Exposure to in tern al radiation following inhalation of contam inated dust; (c) Exposure to in tern al radiation following ingestion of contam in ated c ro p s o r w ater; (d) E x p o su re to in te rn a l ra d ia tio n follow ing the consum ption of c o n ta m in a te d w a te r f r o m w e lls o r th e c o n su m p tio n of crops which have been irrig a ted with contam inated groundw ater. The em erg ency m onitoring req u ired would include the m e a su re m e n t of a i r and s u rfa c e conta m in atio n o v e r a re la tiv e ly sh ort period of tim e. The subsequent m onitoring of the s u r face lay ers of the soil and of nearby surface w aters and vegeta tio n o v e r an ex ten d e d p e rio d of tim e m ig h t be r e q u ir e d. Should p e n e tra tio n to th e s u b s o il be s u sp e c te d, e m e rg e n c y m onitoring should be concerned with the m easurem ent of conta m in a tio n in n e a rb y w e lls u sed fo r d rin k in g w a te r. Owing to the p o ssib ly v e r y slo w m o v em en t of u n d e rg ro u n d w a te r, lo c al w ater supplies used fo r irrig a tio n p u rp oses o r consum ed by p e rs o n s o r d o m e s tic a n im a ls sh o u ld be m o n ito re d o v e r an extended p erio d of tim e. 21

34 4. THE EM ERGENCY MONITORING PROGRAMME A ction following an em ergency w ill need to be rap id and decisive. A s a m a tte r of p ru d e n c e, th e r e f o r e, the p ro c e d u re s to be adopted should, a s f a r a s p o ss ib le, be c o n s id e re d and d ecid ed upon by the a p p ro p ria te a u th o rity b e fo re an a c c id e n t r a th e r than im p ro v ise d a fte rw a rd s in an atm o sp h ere of panic. T his sectio n attem p ts to give guidance on fa c to rs which need to be taken into account when planning both the environm ental m onitoring program m e and the overall e m e r gency sch em e. Planning in the g re a te s t d e ta il is obviously p o ssib le in resp ect of an accident at a fixed installation and em phasis is th e re fo re p la c e d on th is a s p e c t, but th e p rin c ip le s inv o lv ed a r e eq u ally applicable to m onitoring p ro g ram m es and em erg en cy sch em es d e sig n ed to c o v e r o th e r situ a tio n s Formulation of an appropriate monitoring p ro g ra m m e P r e lim in a ry in fo rm a tio n re q u ire d T he p r im a r y aim of any e m e rg e n c y e n v iro n m e n ta l m o n ito rin g p ro g ram m e is to supply the inform ation needed to decide what action, if any, h as to be tak en to lim it the rad iatio n ex posure of m e m b e rs of the p u blic. M o reo v e r, a t the planning sta g e, su fficient inform ation m u st be av ailable to p e rm it the a s s e s s m ent of the co n seq u e n c es of the ty p e s of a c c id e n ta l r e le a s e s to en v ironm en tal m edia w hich can reaso n ab ly be fo re seen and hence the extent of the em erg en cy su rv ey needed. Such in fo rm a tio n, h o w ev er, is v a lu e le s s u n le s s th e r e a r e c r i t e r i a by w hich its sig n ific a n c e c a n be ju d g ed. T he f i r s t r e q u ir e m e n t of th o se p lannin g the e m e rg e n c y e n v iro n m e n ta l m o n i to r in g p ro g ra m m e is, th e r e f o r e, g u id an ce on th e le v e ls of rad iatio n and rad io activ e contam ination co n sid ered significant u n d e r e m erg en cy conditions and, p a rtic u la rly, on the lev els at which rem ed ia l action m ust be considered. T he type of a c tio n re q u ire d to m itig a te th e c o n se q u e n c e s of an a c c id e n ta l r e le a s e w ill depend upon the n a tu re of the p o s tulated accident and the ro u te s through which people a re likely to be exposed to rad iatio n. G en eral guidance on the m agnitude and n a tu re of p o ssib le r e le a s e s is given in se c tio n

35 T he p o te n tia l ro u te s of e x p o su re fro m ra d io a c tiv e m a te r ia l r e le a s e d into the v a rio u s m e d ia have been d e s c rib e d in s e c tio n 3.3. The sig n ifican ce of th e se v a rio u s ro u te s should be d e te rm in e d fo r th e in s ta lla tio n in q u estio n by ex am in in g the so c ia l, d ie ta ry, a g r ic u ltu r a l and o th e r p r a c tic e s of the p o pulations likely to be affected by a rele a se of radioactive m a t e r ia l. Such p o pulatio n s w ill u su a lly be th o se in the v ic in ity of the in s ta lla tio n but the p o ssib ility of e x p o su re of o th e r people e ith e r a s a r e s u lt of an o m alo u s m o v e m e n t of ra d io n u c lid e s in the a ir, o r in su rface o r underground w aters, o r as a r e s u lt of c o n su m p tio n of fo o d stu ffs h a r v e s te d in th e a ffe c te d a r e a sh o u ld be b o rn e in m in d. F r o m th e s e s tu d ie s it w ill beco m e c l e a r w hich m a te r ia ls p ro v id e th e p rin c ip a l ro u te s of e x p o su re and t h e r e f o r e sh o u ld r e c e iv e i n itia l a tte n tio n. L o c a l g e o g ra p h ic a l f e a tu r e s m a y b e su c h th a t so m e p eople m ay be a t g r e a te r r i s k than o th e r s. P r e lim in a ry stu d ie s of w eath er conditions fo r exam ple v a ria tio n s in wind d irectio n and velocity and other facto rs which m ay affect the concentration of air-borne m a te rial o r its deposition on the ground s u r fa c e of m o v e m e n ts of b o d ie s of w a te r in to w hich a c tiv ity m ay be a c c id e n ta lly d is c h a rg e d and, if p o ssib le, of th e d i re c tio n and sp e e d of flow of u n d e rg ro u n d w a te rs in c a s e of p o s s ib le h e a v y c o n ta m in a tio n of th e s o il, sh o u ld t h e r e f o r e be u n d e rta k e n to e s ta b lis h w h e re s a m p lin g w ould be m o s t e ffe c tiv e. W hen c a r r y in g out s ite - s tu d ie s of th is ty p e it is alw ays p ru d en t to c o n s id e r the advice of a p p ro p ria te e x p e rts know ing lo c a l c o n d itio n s. Som e d a ta m ay w ell be a v a ila b le fro m s tu d ie s c a r r ie d out fo r o th e r r e a s o n s G e n e ra l c o n s id e ra tio n s (a) When the re le v a n t inform ation outlined in sectio n has b een c o lle c te d fo r the p a r tic u la r in s ta lla tio n, a m o n ito rin g p ro g ram m e can be fo rm ulated. The type of pro g ram m e needed w ill v a ry a c c o rd in g to in d iv id u a l c irc u m s ta n c e s and only th e m o st g e n e ra l c o m m e n ts can be m a d e. On th e one hand, th e p re lim in a r y s tu d ie s m ay show th a t no accid en t of su fficient m agnitude to have an im p act outside the s ite is fo re s e e a b le. In su ch a c a s e no e m e rg e n c y e n v ir o n m ental m onitoring p ro g ram m e is needed. T his situ atio n is 2 3

36 lik e ly to p r e v a il at in s ta lla tio n s p ro c e s s in g only re la tiv e ly n o n -to x ic n u c lid e s, such a s n a tu r a l u ra n iu m. At th e o th e r e x tr e m e, w id e s p re a d c o n s e q u e n c e s a r e lik e ly to be found, and h en ce e x te n siv e su rv e y s w ill be n eed ed, if th e re is any p o ssib ility of a su b sta n tia l r e le a s e of m ixed fissio n -p ro d u c ts in to th e a tm o s p h e re in an a g r ic u ltu r a l a r e a, and, in p a r tic u la r, of is ijin to the a tm o sp h e re in a m ilk -p ro d u c in g a re a. R e le a s e s to th e a tm o s p h e re, b e c a u s e of th e r a p id ity w ith which activity can be d isp ersed in this m edium, w ill g en erally dem and m o re u rg en t action and thus re q u ire m o re detailed planning than re le a s e s to bodies of w ater o r the ground. Indeed, at in s ta lla tio n s fro m w hich r e le a s e s into a lak e o r the s e a c a n be p o stu la te d, ro u tin e e n v ir o n m e n ta l s u r v e y s a r e often conducted and it is v e ry p ro b a b le th a t any e m e rg e n c y situation can be adequately dealt with by in creasin g the fre quency and sco p e of sa m p lin g u n d e rta k e n fo r ro u tin e p u rp o s e s. T he r e le a s e to th e a tm o s p h e re of n u c lid e s w hich e n te r into fo o d -ch ain s (in p a rtic u la r, iso to p e s of iodine, stro n tiu m and c a e siu m ) r e q u ir e m o re d e ta ile d and e x te n siv e plannin g fo r environm ental m onitoring than a re le a s e of those w hich p re sen t p rim a rily an e x te rn a l ra d ia tio n h a z a rd (for exam ple the noble g a s e s ). (b) U n le ss la r g e r e s o u r c e s of m a n p o w e r and e q u ip m en t a r e a v a ila b le, it is s e n s ib le to r e s t r i c t p lannin g in d e ta il to the "m axim um fo re seeable a cc id en t". At the sam e tim e the plan sh o u ld be k ep t s u ffic ie n tly g e n e ra l and fle x ib le to d e a l w ith o th e r, la r g e r o r s m a lle r, e m e rg e n c ie s sin c e the n a tu re of a c c id e n ts is such th a t it is n e v e r p o ssib le to p re d ic t p re c ise ly w hat w ill o c c u r. Som e im p ro v is a tio n on the b a sic plan w ill lm o st inevitably be req u ired, p a rtic u la rly in the la te r stages a s m o n ito rin g is extended, but ev e ry endeavour m ust be m ade to e n s u r e th a t th e im m e d ia te s u rv e y, i. e. th a t p a r t of th e m o n ito rin g p ro g ra m m e d e sig n e d to p ro v id e in fo rm a tio n on w hich im m ed iate re m ed ia l action can be based, can be c a r r ie d out w ithout h e s ita tio n. It is th e r e f o r e im p e ra tiv e th a t su ffic ie n t v e h ic le s, m o n ito rin g e q u ip m en t and p e rs o n n e l be a v ailab le at a ll tim e s on an o p e ra tio n a l b a s is to m ake a rap id in itia l a s s e s sm e n t of the situ atio n and that the co u rse of action of m o n ito rin g te a m s sent out into the field be c le a rly defined. Since, as pointed out above, a re le a se of radionuclides to the

37 atm o sp h ere is m ore likely to req u ire rap id action than a r e le a s e to b o d ie s of w a te r o r to th e s o il, w ith th e e x c e p tio n p e rh a p s of tr a n s p o r t a c c id e n ts o r o th e r a c c id e n ts involving the rele a se of radionuclides into w ater intended for consum p tion, in the ensuing d iscu ssio n em phasis is placed on the r e q u ire m e n ts fo r dealing w ith an a ir-b o rn e re le a s e. It is not usually n e c e ssa ry, even if the "m axim um fo reseea b le a c c id e n t" could involve a re la tiv e ly la rg e r e le a s e of r a d io active m a te ria ls, to have a larg e re s e rv e of vehicles, equipm e n t an d m e n s e t a s id e s o le ly f o r e m e rg e n c y u s e. Som e in stallatio n s w ill have routine environm ental m onitoring p ro g ra m m e s in o p eratio n. V ehicles used in such routine su rv ey s can be equipped w ith su itab le em erg en cy in stru m e n tatio n, and p ro v isio n can be m ade in th is w ay fo r ra p id au g m en tatio n of th e e m e rg e n c y s e r v i c e s w h ic h a r e im m e d ia te ly a v a ila b le. H ow ever, it is e s s e n tia l th a t su ch f a c ilitie s should be a v a ila b le a s w ill e n s u re th a t th e r e w ill be no d e la y in o b tain in g m e a s u r e m e n ts v ita lly r e q u ir e d fo r ta k in g d e c is io n s on r e m e d ia l a c tio n. In the in te r e s t of ra p id actio n, it is obvio u sly d e s ira b le that th e te a m s r e s p o n s ib le f o r th e im m e d ia te s u rv e y sh o u ld be c e n tre d on the in sta lla tio n. H ow ever, the ad d itio n al su rv ey s w hich m ay su b seq u e n tly be n eed ed could r e q u ir e m o re p e r so n n el and equipm ent than a r e in itia lly a v a ila b le. P ro v isio n should th e re fo re be m ade fo r invoking a s s is ta n c e fro m o th e r s o u rc e s if n e c e s s a ry. A n a ly tic a l s e r v ic e s m u s t a ls o be a d e q u a te to p r o c e s s th e sa m p le s c o lle c te d by the m o n ito rin g te a m s and p la n s should be m ade to su p p lem en t th e se s e rv ic e s by help fro m o th e r s o u rc e s a s re q u ire d. P la n s should a lso be d raw n up fo r the la b o r a to ry p ro c e d u re s to be ad o p ted fo r a n a ly se s of th e e n v iro n m e n ta l sa m p le s c o lle c te d by the m o n ito rin g te a m s. In g e n e ra l the a n a ly tic a l p ro c e d u re s should be sim p le, in o rd e r to avoid u n n e c e s s a ry o v erloadin g of the la b o ra to ry fa c ilitie s, but capable of yielding the re q u ire d inform ation w ith adequate p recisio n in as sh o rt a tim e as po ssib le. Some of these cons id e ra tio n s a r e d isc u sse d in m o re d e ta il in Annex V. (c) T h e ro u te s to be ta k e n by m o n ito rin g v e h ic le s (o r th e flight p aths in the ca se of a irc ra ft) and the lo catio n s of 2 5

38 sa m p lin g p o in ts fo r p a r tic u la r m a te r ia ls sh ould be c le a r ly defined. T he ro u te s chosen should, a s fa r a s p o ssib le, be those w hich would re m a in p a ssa b le u n d e r a d v e rse w eath er conditions and sam p lin g p o in ts should be cap ab le of being re a d ily lo c a te d. T h e o r d e r in w h ich sa m p lin g p o in ts a r e v is ite d sh o u ld, in g e n e ra l, e n su re that m onitoring te a m s w ork inw ard s to w a rd s th e a r e a s of h ig h est contam in atio n thus avoiding u n n e c e ssa ry co n ta m in atio n of in s tru m e n ts and p e rso n n e l. H ow ever, it is im p o rta n t th a t the o v e ra ll ex ten t of the c o n ta m in a tio n of the e n v iro n m e n t be a s c e rta in e d quickly. Som e g u id an ce of th e s e le c tio n of m o n ito rin g and sa m p lin g p o in ts is given in sectio n s and (a). T he advice of e x p e r ts sh ould be so ught if th e r e i s an y doubt re g a rd in g th e a p p ro p ria te n e s s of the lo c a tio n of s a m p lin g s ta tio n s, m e th o d s of sa m p lin g and ty p e s of la b o r a to r y a n a ly s e s. In ad dition to the above ite m s, in stru c tio n s to the m onitoring team s should include a c le a r definition of the p ro c e d u re s to be used in m easuring and sam pling, relaying inform ation to the e m e r g ency c o n tro l c e n tre, tr a n s f e r r in g sam p le s to the a n a ly tic a l la b o r a to rie s and, m o st p a rtic u la rly, in re c o rd in g a ll o b s e r vations and actio n s The need fo r p re -e m e rg e n c y su rv e y s The type of accid e n t en v isag ed m ay o r m ay not c a ll fo r p r e e m e rg e n c y ra d ia tio n s u rv e y s. B ackground su rv e y s a r e e s s e n tia l, fo r ex am p le, if the m axim um u se is to be m a d e of m e a su re m e n ts of gam m a d o s e -ra te s above the ground su rface to p re d ic t the le v e l of contam in atio n lik e ly to be found in food. T h e ir c o m p le x ity is d e te rm in e d by th e m e th o d of e m e rg e n c y s u rv e y s chosen: they should be c a r r ie d out o v e r the ro u te s o r at the lo c a tio n s, and u sin g th e m e th o d s th a t w ould be u s e d in the e v e n t of an e m e rg e n c y. T h e ir fre q u e n c y sh o u ld be d e t e r m in ed by th e v a ria tio n in b ack g ro u n d m e a s u re m e n ts,w h ic h c o n s id e ra tio n, f o r e x a m p le, of the c u r r e n t s itu a tio n w ith r e g a r d to fa ll-o u t could be e x p e c te d to r e v e a l. P r e -a c c id e n t s u rv e y s have a s u b sid ia ry value a s a m e an s of tra in in g p e rso n n e l. If they a r e not c a r r ie d out, it is n e c e s sa ry that m onitoring team s should be m ade fam iliar with p re 26

39 a rra n g e d ro u te s, lo c atio n s and p ro c e d u re s by freq u en t e x e r c is in g. S im ila rly, la b o r a to ry p e rs o n n e l sh ould have e x p e r ie n c e in th e u s e of s ta n d a r d iz e d a n a ly tic a l te c h n iq u e s I n itia l d e te c tio n and a s s e s s m e n t of a c c id e n ta l r e le a s e T he e v e n ts le a d in g up to in itia tio n of the im m e d ia te s u rv e y m a y b e s u m m a riz e d a s: (a) d e te c tio n of an a b n o rm a l co n d ition and (b) a s s e s s m e n t of the sig n ific a n c e of th e a b n o rm a l s i t u a tio n. T h e r e s u l ts of th e s u rv e y a r e u s e d to c o n firm th e e s tim a te d s ig n ific a n c e of th e s itu a tio n an d to d e c id e w hat a c tio n n eed s to be tak en to m in im ize the co n seq u e n c es of the in c id en t. (a) D etectio n of a b n o rm a l r e le a s e s In m any c a s e s re lia n c e fo r d etectio n of an ab n o rm al condition is placed on m onitoring devices installed within the estab lish m e n t. T h e s e in c lu d e in s tr u m e n ts su c h a s c o n tin u o u s a i r s a m p le rs in la b o ra to rie s, leakage d e te c to rs in re a c to r co o l ing sy stem s, c ritic a lity a la rm sy stem s, and continuous m o n ito rin g d ev ic es in sta c k s o r on effluent lin e s. In such c a s e s the p rim a ry re s p o n sib ility fo r in itia tin g a ctio n m ay w ell fa ll upon the o p e ra to r who h ap p en s to be a le rte d by the in sta lle d a la rm sy ste m. Standing in stru c tio n s should th e re fo re specify w hat he is re q u ire d to do and, p a rtic u la rly, to whom he should r e p o r t. L e s s co m m o n ly, p a r t of an e m e rg e n c y m o n ito rin g program m e m ay be operated continuously as p art of an op eratio n a l d etectio n sy ste m. F u r th e r re fe re n c e to su ch m ethods is m ade in section 5. (b) P r e lim in a ry a s s e s s m e n t of the sig n ifican ce of a r e le a s e T he sig n ific a n c e of a r e le a s e can be a s s e s s e d only a f te r the event, but it is p o ssib le to m ake p ro v isio n s in the em erg en cy p lan to e a s e th e ta s k of the p e rs o n c a lle d upon to c a r r y out th is a s s e s s m e n t. Since th is ta s k is one w hich involv es su b s ta n tia l re s p o n s ib ility, a r r a n g e m e n ts sh o u ld be m a d e f o r s e v e r a l co m p eten t in d iv id u als to be av a ila b le at s h o rt notice a t a ll tim e s. 27

40 (i) E stim a tio n of the m agnitude of a r e le a s e. An e s ta b lis h m ent m ay be such that it is possib le to lis t those buildin g s o r la b o r a to r ie s in w hich th e a m o u n ts of n u c lid e s held a r e su fficient, in th e o ry, to give r is e to an o ff-site e m e rg e n c y should th e y be in v o lv ed in an in c id e n t. In d raw in g up su ch a lis t c o n s id e ra tio n should be g iven to th e p h y s ic a l fo rm in w hich th e n u c lid e s a r e h e ld and w hether they a re contained, fo r such fa c to rs w ill influ en ce, fo r e x a m p le, th e p ro p o rtio n of th e m a te r ia l r e le a se d a s the re s u lt of a fire. In any c a se c le a r in s tru c tio n s should be laid down th a t a ll in fo rm a tio n a v a ila b le fro m the site of the accident should be relayed to the r e sponsible p erso n in charge as soon as possible. (ii) A cquisition of m ete o ro lo g ical and hydrolo g ical d a ta. The p re v a ilin g w e a th e r co n d itions m ay profoundly a ffe c t the s ig n ific a n c e of an a b n o rm a l r e le a s e to th e a i r. It is th e re fo re e s s e n tia l th a t the p e rs o n re s p o n s ib le fo r the in itia l a s s e s sm e n t should have im m ed iate a c c e s s to m e te o ro lo g ic a l in fo rm a tio n. S u fficien t e q u ip m e n t sh ould be in sta lle d on the site at le a s t to p ro v id e an in d ication of wind d ire c tio n and speed, and standing a rra n g e m e n ts for obtaining supplem entary inform ation from other m e te o ro lo g ic a l s ta tio n s sh ould be d e ta ile d in th e o v e ra ll e m e rg e n c y p lan. M eteorological data and, in the case of re le a s e to a riv e r, inform ation on its ra te of flow are also esse n tia l to ens u r e th a t the m o n ito rin g te a m s im m e d ia te ly a v a ila b le a re deployed as effectively as possible after an accident. T here w ill be le ss need for urgency in the case of a r e lease to other bodies of w ater but inform ation of the p re v a ilin g w inds and d ire c tio n of w a te r m o v em en t m ay be re q u ire d at a la te r sta g e O rgan ization and staffin g O rganization C o n tro l of e m e rg e n c y a rra n g e m e n ts w ill be e x e rc is e d by an e m e rg e n c y c o n tro l o rg a n iz a tio n lo c a te d in an a d e q u a te ly 2 8

41 equipped c e n tre so situ ated that it w ill re m a in ten able under the con d ition s of a postulated e m e rg en cy. T he m o n ito rin g o rg a n iz a tio n fo rm s a com ponent p a rt o f the em erg en cy co n tro l organization. It w ill co n sist e sse n tia lly of: (a) M onitoring co n tro l cen tre It i s th e ta s k of the m o n ito rin g c o n tr o l c e n tr e to d ir e c t the m o n ito rin g te a m s, to c o lle c t and a s s e s s th e d ata p rovid ed by th e se te a m s, and to p re d ict fu ture tre n d s. The in fo r m a tion assem b led by the m onitoring co n tro l cen tre w ill be tr a n s m itted to the em erg en cy co n tro l ce n tre. The use of a co n tro l cen tre in a p ra ctice e x e r c is e is illu stra te d in F ig. 1. FIG. 1. Emergency control centre being used for a practice exercise (Hanford Project - USA) (b) M onitoring team s It i s the ta s k of the m o n ito rin g te a m s to p e rfo rm th e m o n i to rin g o p eration s and to tra n sm it the re s u lts of the m e a s u re m e n ts to the m o n ito rin g c o n tro l c e n tr e. T h e s e m o n ito rin g 29

42 o p e ra tio n s w ill in c lu d e th e in itia l su rv e y and any su b se q u e n t s u rv e y s re q u ire d. In te rp re ta tio n of the re s u lts obtained by the m o n ito rin g team s w ill re q u ire e x p e rtis e w hile execu tio n of th e m e a s u r e s planned to m in im iz e th e c o n s e q u e n c e s of th e a c c id e n t w ill a lm o s t c e rta in ly re q u ire the c o -o p e ra tiv e e ffo rts of a n u m b e r'o f o r g a n iz a tio n s. It is th e r e f o r e d e s ir a b le th a t lia is o n b etw een the m a n a g e m en t of the e s ta b lis h m e n t and o u tsid e a u th o ritie s be m a in ta in e d, and it is e s s e n tia l th a t th e e m e rg e n c y p la n in c lu d e a r r a n g e m e n ts f o r n o tify in g n o t o n ly k ey p e r s o n n e l b u t a ls o o th e r o r g a n iz a tio n s w h ic h m a y b e c o m e in v o lv e d.. S taffin g An a p p ro p ria te n u m b er of te c h n ic a l and su pporting sta ff m u st be av ailable to m an the m onitoring c o n tro l c e n tre and to fo rm the m onitoring te a m s. (a) M onitoring control centre The m onitoring control centre should operate under the d ire c tion of an ex p e rt in the field of rad iatio n p ro te ctio n who would d ir e c t th e m o n ito rin g te a m s, c h a r t th e r a d ia tio n an d c o n tam in atio n lev els and provide the tech n ica l inform ation, in clu din g p re d ic te d fu tu re tre n d s, re q u ire d by the e m e rg e n c y c o n tro l c e n tre. He should be a s s is te d by an adequate num ber of technological and other supporting staff. F o r m ajor e m e r g e n c ie s it m ay be n e c e s s a r y to r e c r u i t a d d itio n a l s ta ff fo r c o n tro llin g th e su b se q u e n t s u rv e y s. (b) M o n ito rin g te a m s and a n a ly tic a l s e r v ic e s The m onitoring team s w ill be called upon to p erfo rm the in i tia l su rv ey and any subsequent su rv ey s req u ired. (i) T he in itia l s u r v e y. A s u ffic ie n t n u m b e r of te c h n ic a l p e rso n n e l m u st be a v ailab le at v e ry sh o rt notice to fo rm team s to m an the survey vehicles and to provide the an a ly tic a l s e r v ic e s. In g e n e ra l, each v e h ic le te a m should c o m p ris e a t le a s t one te c h n o lo g ic a l sta ff m e m b e r, who w ould d ir e c t th e p ro c e d u re s and c o m m u n ic a te w ith th e

43 m o n ito rin g c o n tro l c e n tre, to g e th e r w ith su pporting sta ff who w ould m o n ito r ra d ia tio n and c o n ta m in a tio n le v e ls, co llect sam p les and p erfo rm sim ple g ro ss activity m eas u r e m e n ts. In a d d itio n a s s is ta n t s w ould be r e q u ir e d to d rive the vehicle and to pack, label and sto re the co l le c te d s a m p le s. T he n u m b e r of te a m s w ould depend on the fa c ilitie s av a ila b le and the m agnitude of the re le a s e. Suitably tra in e d technolo g ic al sta ff a r e a lso re q u ire d fo r the ra d io c h e m ic a l a n d /o r s p e c tro m e tric a n a ly sis of the s a m p le s c o lle c te d by the su rv e y te a m s. F o r an a e r ia l su rv e y a tech n o lo g ic al sta ff m e m b e r should be av ailable to d irect the pilot, to reco rd radiation levels and to com m unicate with the m onitoring control cen tre. (ii) Subsequent su rv ey s. The m ain requirem ent is for a possib ly s u b s ta n tia l in c r e a s e in th e n u m b e r of m o n ito rin g te a m s and in th e n u m b e r of p e rs o n n e l a v a ila b le fo r the handling of sam p les and fo r the p erfo rm an ce of the an a ly tic a l s e rv ic e s. In g e n e ra l it w ill be n e ith e r n e c e s s a ry nor d esirab le to have available on the site a ll the perso n n e l r e q u ir e d to p e r f o r m th e su b s e q u e n t s u r v e y s, but p r io r a rra n g e m e n ts should be m ade to se c u re th e ir s e r v ic e s ra p id ly w hen re q u ire d. (c) C om m unication staff The m o n ito rin g te a m s should be able to tra n s m it info rm atio n to, an d r e c e iv e in s tr u c tio n s fro m, th e m o n ito rin g c o n tr o l c e n tr e in th e s h o r te s t p o ssib le tim e. T he e m e rg e n c y c o n t r o l c e n tre should a ls o be ab le to c o m m u n icate ra p id ly w ith the m o n ito rin g c o n tro l c e n tre and w ith the v a rio u s in te re s te d a u th o ritie s. T he u se of te le x and sh o rt-w a v e ra d io co m m u n ic a tio n s y ste m s in additio n to the n o rm a l telephone s y ste m and th e p r e p a ra tio n in a d v an ce of a s e t of c o d e s could m a te ria lly a s s is t in the tra n s m is sio n of inform ation and in s tru c tio n s. It w ill be n e c e s s a ry to e n su re th a t com petent p e rso n s a r e a v a ila b le to o p e ra te s u c h s p e c ia liz e d c o m m u n ic a tio n s y s te m s. (d) A v a ila b ility of a d d itio n a l s ta ff A rra n g e m e n ts should be m ade in ad v an ce fo r the r e s o u r c e s to be in c re a s e d ra p id ly fo r the su b se q u e n t su rv e y s. It m ay 31

44 a ls o be n e c e s s a r y to a r r a n g e fo r th e ra p id r e c r u itm e n t of s k ille d p e rs o n n e l to d e a l w ith s p e c ia l p ro b le m s a r is in g in the su rv e y s and fo r the se c u rin g of additional a ssis ta n c e fro m o th e r e sta b lish m e n ts, fro m o th e r c o u n trie s and possibly fro m a p p r o p r ia te re g io n a l o r in te r n a tio n a l o rg a n iz a tio n s. T h e p ro c e d u r e s and a u th o riz a tio n r e q u ir e d fo r a u g m e n tin g th e re s o u rc e s and fo r en listin g such additional a ssista n c e as m ay be r e q u ir e d sh o u ld be c l e a r ly la id dow n in th e e m e rg e n c y p la n s.

45 5. EM ERGENCY MONITORING PROCEDURES T he p ro c e d u re s u sed in e n v iro n m e n ta l m o n ito rin g can co n v e n ie n tly be g ro u ped into th r e e p h a se s: d ete c tio n, in itia l su rv e y and subsequent su rv ey s. O ccasionally, as outlined in section 4, m onito rin g m ay be conducted continuously in o rd e r to serv e as a d ete c tio n sy ste m. The in itia l, im m ed iate su rv e y is of p rim e im p o rtan ce fo r it is on the re s u lts obtained by m o n ito rin g te a m s w ithin the fir s t few h o u rs follow ing an a c c id e n t th a t d e c isio n s on re m e d ia l a c tio n s m u st be b a se d. S ubsequent s u rv e y s d e sig n ed to ex ten d m e a s u r e m e n ts to m a te r ia ls w hich r e q u ir e le s s u rg e n t a tte n tio n, to o b tain m ore accurate inform ation on the situation and to follow its developm ent, and to obtain scientific inform ation on, for exam ple, the b e h av io u r of the re le a s e d ra d io a c tiv e m a te ria l, can be c a r r ie d out at $ slig h tly m o re le isu re ly pace since th e re w ill be tim e fo r each step to be co n sid ere d E nvironm ental m onitoring used a s a detection sy ste m It is usually m ore sa tisfa c to ry to m ake provision fo r d etec t ing th e e m e rg e n c y a t its s o u rc e r a th e r th a n in the e n v iro n m e n t but d e te c tio n by e n v iro n m e n ta l m o n ito rin g m ay be r e quired in som e situations, possibly, fo r exam ple, n ear in te r national fro n tiers. O ff-site sy ste m s m ay include such d ev ic es a s continuous a ir - s a m p l e r s o r w a te r - s a m p l e r s o r d e v ic e s f o r c o n tin u o u s ly sc a n n in g th e sk y o r b o d ie s of w a te r f o r r a d ia tio n, in e a c h c a se the re a d in g s being te le m e te re d back to a c o n tro l c e n tre. T hey a ll have the d isad v a n ta g e th a t the d e te c to r s n eed to be c o n sid e ra b ly m o re se n sitiv e than if site d n e a r to the p o ssib le p o in t of r e le a s e and a ls o n e e d to be e x tr e m e ly r e lia b le if duplication is to be avoided. System s intended to detect a i r b o rn e r e l e a s e r e q u ir e th e d e te c to r s to be c lo s e ly sp a c e d, p o ssib ly a t 10 in te r v a ls, if a n a rro w p lu m e of a c tiv e m a t e r i a l is n o t to be m is s e d, and, sin c e th e y sh ould be f a r en o u g h f r o m th e p o s s ib le p o in ts of r e l e a s e to m a k e it u n lik ely that they w ill be w ithin the "sk ip d istan ce" of a re le a se, and should a lso c o v e r a ll populated b e a rin g s fro m the in s ta l lation, such s y ste m s can be v e ry expen siv e. The u se of a ir - s a m p le r s in tro d u c e s c o m p lex te c h n iq u e s, if e a r ly w a rn in g 33

46 i s r e q u ir e d, b e c a u s e of th e p r e s e n c e o f th e n a t u r a l d e c a y p ro d u c ts of ra d o n and th o ro n. H ow ever, if tim e can be a l low ed f o r th e s e to d e c a y, a s im p le m e a s u r e m e n t of g r o s s a lp h a - o r g ro s s b e ta -a c tiv ity wiu in d ic a te w h eth e r conditions a r e s e rio u s ly ab n o rm a l, although it m u st alw ays be re m e m b ered that the re s u lts cannot be in te rp re te d in te rm s of h azard to m an. C o n tin u o u sly o p e ra te d o f f - s ite s y s te m s h av e th e ad v a n ta g e th at they can provide a rap id ind ication, not only th at a r e le a se to the environm ent has taken place, but also of the d i re c tio n in w hich the re le a s e d m a te ria l is m oving The in itia l s u r v e y The overriding consideration in the early phases of the m onito r in g p ro g ra m m e m u s t be sp e e d. M e a s u re m e n ts sh o u ld th e re fo re be lim ite d to th o se n e c e s s a ry to e s ta b lis h w h eth e r im m e d ia te r e m e d ia l a c tio n is n eed ed, and th e a c c u ra c y of th e s e m e a s u re m e n ts should be su b o rd in a te d to th e need fo r aking them in tim e fo r the r e s u lts to be u sefu l. N on-specific m e a su re m e n ts,, such a s the d e te rm in a tio n of to ta l b e ta -a c tiv ity o r of g a m m a -ra d ia tio n le v e ls in the e n v iro n m e n t, w hich a r e n o rm a lly d e p re c a te d in su rv e y s c a r r ie d out fo r p u rp o se s of rad io lo g ical protection, m ay th e re fo re becom e the m ethods of choice in the in itia l e m erg en cy su rv e y. The choice of the ap p ro p riate m ethods depends upon the com position of the m a t e r i a l re le a s e d and upon the m ediu m (a ir, w a te r o r ground) into which the m a te ria l has been predom inantly re le a sed. The m o st u rg e n t a c tio n w ill a lm o st c e rta in ly be c a lle d.for in the c a s e of a r e le a s e to th e a tm o s p h e re b e c a u se of the ra p id ity of d is p e rs io n of a c tiv ity in th is m e d iu m. The v ario us p ro ced u res which m ay have to be used in the in i t i a l p h a se a r e d is c u s s e d in th e a p p ro x im a te o r d e r of th e ir p r io r ity A s s e s s m e n t of a ir - b o r n e c o n ta m in a tio n In th e c a s e of a r e le a s e to th e a tm o s p h e re th e m o st u rg e n t p ro b le m w ill be a s s e s s m e n t of the h a z a rd fro m in h alation o r, in the case of noble g ases, fro m ex te rn a l exposure fro m the 3 4

47 clo ud. If the a c c id e n t h a s given r i s e to a sudden r e le a s e of s h o r t d u ra tio n, no a c tio n to lim it e x p o su re i s lik e ly to be fe a s ib le but if th e r e l e a s e i s d e la y e d o r p ro lo n g e d, a c tio n su ch a s te m p o ra ry ev acu atio n m ay be p o ssib le and a i r s a m p lin g sh ould th e r e f o r e be s ta r te d a s ra p id ly a s p o s s ib le in a d ir e c tio n d ow n-w ind fro m th e p o in t of r e le a s e. M easu rem e n ts m ay be m ade e ith e r by m ean s of fixed d ev ices (see se c tio n 5.1 ) o r by m o b ile equipm ent. In the la tte r c a se it is, of c o u rse, im p o rta n t th a t som e co m m u n icatio n sy ste m be av ailable to p e rm it re s u lts to be tra n s m itte d to the co n tro l cen tre as soon as they a re obtained. It i s d iffic u lt to o b ta in a r e p r e s e n ta tiv e s a m p le of a f a s t - m oving cloud and, in d ee d, the n e e d fo r sp e e d w ill p ro b a b ly be so o v e rrid in g th a t th e r e w ill be tim e only fo r v e r y r u d i m e n ta ry m e a su re m e n ts. Any a ir m onitoring that can be done in the in itia l p h ase should th e re fo re p ro b ab ly be re g a rd e d a s su pplem en tin g the In fo rm a tio n obtained fro m the p re lim in a ry a s s e s s m e n t of th e m a g n itu d e of th e a c c id e n t an d f r o m an y a ir - m o n ito r in g e q u ip m e n t in s ta lle d o n - s ite R a p id a s s e s s m e n t of th e a r e a a ffe c te d T h e m o s t ra p id a s s e s s m e n t of th e e x te n t of e n v iro n m e n ta l co n tam in atio n can be m ade by m e a su re m e n t of g ro s s activ ity. The a r e a affected m ay be anything fro m a few sq u a re m e tre s, in th e c a s e of a s p ill in to th e gro u nd, to m any th o u sa n d s of sq u a re m e tre s, in the c a se of a la rg e a ir-b o rn e re le a s e. Under the la tte r c irc u m s ta n c e s only a rough e s tim a te of the e x te n t of c o n ta m in a tio n c a n be m a d e in th e in itia l s ta g e s an d a c c u r a te d e lin e a tio n of th e a ffe c te d a r e a m u s t be le ft u n til tim e and a u g m e n te d f a c ilitie s p e r m it. M ost r e l e a s e s of im p o rta n c e a r e lik e ly to in c lu d e m ix ed f is s io n - p r o d u c ts o r b e ta -g a m m a e m i t t e r s. Such n u c lid e s a r e r e la tiv e ly e a s ily d e te c te d on th e g ro u n d o r in w a te r by g a m m a -ra d ia tio n s u rv e y s. Although the presen ce of alp ha-em ittin g o r b eta -em ittin g nuc lid e s can be d e te c te d w ithout sam p ling, fo r any q u an titativ e a s s e s s m e n t of th e a m o u n ts p r e s e n t sa m p lin g is n e c e s s a r y. It i s u n lik e ly th a t im m e d ia te s u rv e y s f o r a lp h a -a c tiv ity on 35

48 th e g ro u n d w ill be c a lle d fo r e x c e p t in th e v ic in ity of a r e le a s e in v o lv in g a s ig n ific a n t q u a n tity o f an a l p h a - e m i tte r. (a) G a m m a - r a d ia tio n s u rv e y s M e a su re m e n t of g a m m a -ra d ia tio n le v e ls in the e n v iro n m en t is of p a rtic u la r value in the case of w idesp read d issem in atio n of a c tiv ity due to a re le a s e to the a tm o s p h e re. The r e s u lts o btained not only in d icate the ex ten t of co n tam in atio n but can a lso be used to e stim a te the to ta l g a m m a -ra y dose to exposed p e rs o n s and to p re d ic t the le v e ls of c o n ta m in a tio n lik e ly to be found in som e foods. T his capability of prediction is p a r tic u la r ly v a lu a b le in th e c a s e of 131I r e l e a s e s to the a tm o sp h e re in a d a iry -fa rm in g a re a. If the affected a re a is larg e, it m ay take som e tim e to apply r e s tr ic tio n s to the consum ption o r s a le of m ilk, the p re d o m in a n t s o u rc e of e x p o su re u n d e r su c h c irc u m s ta n c e s, and it is th e r e f o r e n e c e s s a r y to have an e s tim a te of the p o ssib le le v e l of 131I in m ilk w ithin a few h o u rs. H ow ever, sin ce a n im a ls a re m ilked at d is c re te in te rv a ls, no sig n ific a n t a c tiv ity m ay be found in m ilk fo r up to 24 h o u rs a f te r d e p o sitio n on h e rb a g e h a s o c c u r r e d, and a n a ly s is of m ilk its e lf d u rin g the e a rly s ta g e s m ay th e re fo re give m is le a d in g r e s u l ts. P ro v id e d the co m p o sitio n of the d e p o site d m a te r ia l is known, it is p o ssib le to e s tim a te th e am ount of 1311 p re s e n t fro m g am m a e x p o s u r e - r a te m e a s u re m e n ts and so to p r e d ic t w h at th e m a x im u m le v e l of c o n ta m in a tio n of m ilk is lik e ly to b e. T he v a lu e of g a m m a -s u rv e y s fo r th is p urpose is g re a tly enhanced if background lev els a re available fro m p re -e m e rg e n c y su rv e y s (see se c tio n 4.2 ). E x p o su re - ra te s sufficiently high to w a rra n t evacuation of the co n tam i n a te d a r e a in o r d e r to c o n tro l e x te rn a lly re c e iv e d ra d ia tio n dose a re e a sily d etectab le when o rd in a ry ionization ch am b e rs o r s c in tilla tio n - c o u n te r in s tr u m e n ts a r e u s e d. E x p o s u re - r a te s c o rre sp o n d in g to sig n ific a n t le v e ls of co n ta m in atio n in fo o d stu ffs a r e n o rm a lly d e te c ta b le only w ith m o re s e n s itiv e equipm ent (see sectio n 6). S ince e m e rg e n c y f a c ilitie s a r e lik e ly to be lim ite d a s w e ll a s o v e rlo a d e d in th e in itia l s ta g e s, i t is p ru d e n t to co n fine th e s u rv e y to th o s e a r e a s w h e re c o n ta m in a tio n c a n be e x

49 p e c te d, h av in g r e g a r d to th e w e a th e r c o n d itio n s p re v a ilin g a t th e tim e of r e le a s e. In so m e c o u n tr ie s, p r e - s e le c te d ro u te s fo r v e h ic le s a r e c h o sen, a s f a r a s p o ssib le, so a s to fo rm a p o la r g rid a ro u n d th e in s ta lla tio n, i. e. so a s to lie on c o n c e n tric c ir c le s su rro u n d in g the in s ta lla tio n o r on ra d ii of th e s e c i r c l e s. B e c a u se it is b e lie v e d th a t, u n d e r m o s t accid en t conditions likely to be encountered, the la te ra l sp read of a plum e of a c tiv ity would not exceed 30, the ra d ia l ro a d s a r e ch o se n a t ro u g h ly 30 in te r v a ls. T h u s, in th e o ry, th e im m e d ia te su rv e y would need to c o v e r only two 30 s e c to rs. G a m m a -ra d ia tio n m e a s u r e m e n ts c a n be m a d e in a n u m b e r o f w ay s and th e m e th o d d e c id e d upon w ill d e p e n d upon th e a r e a th a t the p re lim in a ry s tu d ie s o u tlined in se c tio n 4 have show n to n eed c o v e rin g and upon th e n a tu r e of th e t e r r a i n a ro u n d th e e s ta b lis h m e n t. The sim p le st m ethod is to use portable b a tte ry -o p e ra te d b e ta / g a m m a s u r v e y - m e te r s of th e ty p e s d e s c rib e d in s e c tio n 6. T h e s e c a n be c a r r ie d in th e hand. If th e r e s u l t s a r e to be q u a n tita tiv e, m e a s u r e m e n ts should be m ade a t a n u m b e r of p re -d e te rm in e d p o sitio n s w ith the d e te c to r held at a standard h e ig h t (u su a lly 1 m ) above th e g ro u n d s u r f a c e. U n le ss the m e a s u r e m e n ts a r e r e q u ir e d fo r a s p e c ific p u rp o s e, th e s e p o sitio n s should be aw ay fro m ro a d s u rfa c e s, t r e e s, hedges o r buildings, -all of w hich m ay d is to rt the d istrib u tio n. G reat c a r e sh o u ld be ta k e n to a v o id c o n ta m in a tio n of th e i n s t r u m e n ts. To in c r e a s e m o b ility, m en and in s tru m e n ts can, of c o u rse, be tra n s p o rte d in ro ad v e h ic le s, b o a ts o r a ir c r a f ts. T h is typ e of s u rv e y is c a p a b le of p ro v id in g a ra p id a s s e s s m ent of the ex ten t of the contam in ated zone. Some c a re has to be taken that, as fa r as possible, road v e h ic le s w ork in tow ard s a re a s of h ig h er contam ination in o rd e r to avoid in v a lid a tio n of m e a s u r e m e n ts ow ing to g r o s s c o n ta m in a tio n of th e v e h ic le s th e m s e lv e s. T he e ffe c t of c o n ta m in a tio n can be m in im iz e d by m o u n tin g th e d e te c to r on a p o le above th e v e h ic le. T he g ain o b ta in e d by v ir tu e of th e d e te c to r " s e e in g " a g r e a te r a r e a of th e g ro u nd p a rtly c o m p e n s a te s f o r th e lo s s r e s u ltin g fro m th e in s tr u m e n t b ein g f a r th e r fro m th e c o n ta m in a te d s u r f a c e. U ndoubtedly the m o s t ra p id g a m m a -s u rv e y can be ach iev ed by u sin g in s tru m e n ts m o u n ted in a i r c r a f t. A e r ia l s u rv e y s 37

50 a ls o have the ad v an ta g e th a t m o v e m e n ts of a i r c r a f t a r e not r e s t r i c te d by g ro u n d c o n d itio n s. H e lic o p te rs have p ro v e d to be v alu a b le fo r th is p u rp o se. No s p e c ia l in s tru m e n ts o r tra in e d p e rso n n e l, o th e r th a n the pilot, a r e re q u ire d ; s ta n d a rd p o rta b le equipm ent o p e ra te d by the n o rm a l m o n ito rin g s ta ff w ill su ffic e. H e lic o p te rs m ay o p e ra te fro m an y open sp a c e and in w e a th e r c o n d itio n s th a t w ould p ro h ib it th e u se of fixed-w ing a ir c r a f t. T hey have the fu rth e r advantage th a t they can be u sed to co lle ct sam p les of, fo r exam ple, v eg e ta tio n fro m a r e a s of high c o n ta m in a tio n. T he u se of fix e d - w ing a ir c r a f t h a s th e s e rio u s d is a d v a n ta g e th a t a v a ila b ility m a y be r e s t r i c te d ow ing to bad w e a th e r c o n d itio n s. In a d d itio n, s in c e th e a i r c r a f t h a s to be' s p e c ia lly eq u ip p ed fo r th e p u rp o s e, th e c o s t of m a in ta in in g a s p e c ia l a i r c r a f t and a tr a in e d c re w i s high. E x am p les of m ethods in c u rre n t u se fo r c a rry in g out gam m a- s u rv e y s fo r p re d ic tio n p u rp o s e s a r e given in A nnex III. If s im p le g a m m a -d e te c tin g in s tr u m e n ts a r e e m p lo y e d and it is d e s ire d to u se the re s u lts of the g a m m a -su rv e y fo r e s tim a tin g le v e ls of in d iv id u a l n u c lid e s, s a m p le s fro m the ground su rface m ust be exam ined in o rd e r that the com positio n of the d ep o sited m a te ria l can be a s c e rta in e d. An a l t e r n a tiv e is to em ploy p o rta b le g a m m a -s p e c tro m e te rs. T h e se can e ith e r be re la tiv e ly sim p le in s tru m e n ts ch an n elled on to one p a r t ic u la r n u c lid e, e.g. 131I, o r th e y m a y be m u ltichannel in stru m e n ts. Since in te rp re ta tio n of g a m m a -sp e c tra i s lik e ly to be d iffic u lt u n d e r fie ld c o n d itio n s, it h a s b e e n su g g e ste d th a t, if su ita b le eq u ip m en t is a v a ila b le, re a d in g s should be te le m e te re d to th e c o n tro l c e n tre w h e re th e y m ay be fed in to a c o m p u te r o r o th e rw is e p ro c e s s e d a s d e s ir e d. (b) C o n ta m in a tio n s u rv e y s T h e e x te n t of c o n ta m in a tio n w ith a lp h a -e m ittin g o r b e ta - em ittin g n u clid es is best d eterm in ed by sam pling. The am ount of a c tiv ity d e p o site d on th e g ro u n d s u rfa c e a s th e r e s u lt of an a ir - b o r n e r e le a s e c a n be e s tim a te d e ith e r by sa m p lin g th e v e g e ta tio n c o v e r alo ne o r to g e th e r w ith th e u p p e r la y e r of the s o il. M e a su re m e n t of g r o s s a c tiv ity is p ro b a b ly a c ceptable in the e a rly phase of m onitoring u n less an estim ate

51 i s r e q u ir e d of th e am ount of in d iv id u a l n u c lid e s p r e s e n t fo r p u rp o s e s of p re d ic tio n. S a m p le s of h e rb a g e, e t c., o b ta in e d to a s s i s t in th e i n t e r p re ta tio n of g a m m a -m o n ito rin g r e s u l ts, m u st be c o lle c te d and exam ined v e ry ra p id ly if re m e d ia l action is co n tem p lated on th e b a s is of th e g a m m a -s u rv e y. T he s a m p le s a r e p r e fe ra b ly obtained fro m p o in ts in the v ic in ity of the in s ta lla tio n s e le c te d on th e a d v ic e of a p p ro p ria te e x p e r ts. K now ledge of the fo o d -ch ain b eh av io u r of the re le a s e d ra d io a c tiv ity can be com bined w ith the e stim a tio n of d ep o sitio n to in d icate the p robable contam ination of a g ric u ltu ra l and biological sam p les. On the o th e r hand, if p re lim in a ry a s s e s m e n ts of the m a g n i tude of the r e le a s e su g g est th a t its sig n ifican ce in re s p e c t of ex p o su re of the g e n e ra l public is m arg in al, it m ay be prudent to w ait u n til sa m p le s of foodstuffs have been exam ined before initiating rem ed ial action. E x am p les of m ethods in c u rre n t u se fo r sam ple collection and field evaluation a re given in Annex IV E xam ination of w ater and food Sam pling and ex am in atio n of w a te r and food w ill not re q u ire th e sa m e u rg e n c y a s th e p ro c e d u re s d e s c rib e d ab o v e. T he e ffe c t of a ir - b o r n e r e le a s e s on w a te r su p p lie s is unlik ely to be sig n ifican t a s co m p ared w ith the in h alatio n h a z a rd and the in g estio n h a z a rd fro m co n tam in ated food. On the o th e r hand, a r e le a s e to a r iv e r, to a lak e o r to the g ro u nd m ay lead to ra p id and s e r io u s c o n ta m in a tio n of w a te r s u p p lie s. A d e cision to prohibit tem p o rarily the use of w ater for human consu m p tio n o r fo r in d u s tr ia l p u rp o s e s c an n o t o r d in a r ily w ait upon the re su lts of sam pling and analysis if p relim inary m eas u re m e n ts of g r o s s a c tiv ity have in d ic a te d th a t th e r e le a s e m ay have sig n ific a n t c o n se q u e n c e s. A main aim of em ergency environm ental m onitoring is to p ro vide tim e ly in fo rm a tio n on w hich m e a s u re s can be b ased fo r p rev en tin g, to the ex ten t p ra c tic a b le, e x c e ssiv e ex p o su re of m e m b e rs of the public. Such m e a su re s include the avoidance of intake by ingestion of rele ased radionuclides by early contro l, w here w a rra n te d, of fo o d -p roducts w hich w ill be pro m p tly c o n su m e d by m a n. T he fo o d -p ro d u c ts r e q u ir in g th e m o s t 3 9

52 im m ed iate atten tio n a re th e re fo re those which w ill be rap id ly c o n ta m in a te d an d w h ich a r e lik e ly to be c o n su m e d s h o r tly a fte rw a rd s. T h ese w ill include m ilk (see se c tio n (a)), f r e s h g ra in, v e g e ta b le s, rip e n in g fru it, and c e r e a ls re a d y fo r h a rv e s tin g in th o se p a r ts of the w o rld w h e re f r e s h ly - h a rv e s te d g ra in is eaten at once. The te m p o ra ry c o n tro l of m ilk is r e f e r r e d to at s e v e r a l p o in ts of th is m a n u al; it is a control m easure which has been introduced in the past following r e le a s e of ra d io n u c lid e s to the en v iro n m en t. It is e s p e c ia lly im p o rtan t, how ever, to b e a r in m ind that it is re fe rre d to only a s an e x am p le and th a t the g e n e ra l co n cep t w ould be eq u ally a p p licab le to o th e r fo o d -p ro d u c ts w hich a r e intended fo r im m ed iate h arv estin g and consum ption. It is e v id e n t th a t, once ag ain, a r e le a s e to th e a tm o s p h e re dem ands the m ost rap id action sin ce contam ination of foods tu ffs fro m w a te r - b o r n e a c tiv ity is lik e ly to be d e la y e d in c o m p a r is o n w ith th a t fro m a i r - b o r n e a c tiv ity. In g e n e ra l, m o n ito rin g of w a te r and of fo o d stu ffs o th e r th a n th o s e m e n tio n e d can th u s be c a r r ie d out at a slig h tly m o re le isu re ly pace and can be re g a rd e d as form ing p a rt of a phase of e m e rg e n c y m o n ito rin g s u b se q u e n t to th e i n itia l s u rv e y S u b se q u e n t s u r v e y s O nce d e c is io n s on u rg t r e m e d ia l a c tio n have b e e n ta k e n m o r e tim e c a n be g iv e n to c o n s id e r in g s u b s e q u e n t s te p s. The ra p id ity w ith which th is subsequent action can be c a rrie d out w ill depend, to a la rg e d eg ree, on the extent to w hich the fa c ilitie s o rig in a lly av ailable to d eal w ith the e m erg en cy can be augm en ted. The a im s of the m e a s u re m e n ts m ade at th is sta g e should be fourfold: (a) To re -e x a m in e the m e a su re s taken during the in itia l phase an d to d e c id e w h e th e r th e y sh o u ld be m a in ta in e d, e x ten d e d o r c o n tra c te d in th e lig h t of m o re a c c u r a te i n fo rm a tio n on the zo n es a ffe c te d and on the le v e ls of c o n ta m in a ti on; (b) To follow th e tre n d of c o n ta m in a tio n on the g ro u nd, in w ater and in foodstuffs and to d eterm in e when re s tric tio n s can be rem oved and contam inated a re a s retu rn ed to n o r m al use; 4 0

53 (c) (d) T o e v a lu a te th e c o n se q u e n c e s of th e a c c id e n t in te r m s of ra d ia tio n d o se s to p eople and, to a l e s s e r e x ten t, to liv e sto c k ; To o b tain sc ie n tific in fo rm a tio n on the b e h a v io u r in the en v iro n m en t of the re le a s e d ra d io a c tiv e m a te r ia l in o r d e r to provide data, fo r exam ple, to allow m o re a c c u ra te th e o re tic a l a s s e s s m e n ts of p o ten tial h a z a rd s to be m ade R e a sse ssm e n t of in itia l m e a su re s G a m m a -s u rv e y s, su p p lem en ted if n e c e s s a r y by sam p lin g of m a te r ia ls su c h a s h e rb a g e and w a te r, sh o u ld be u s e d a s a f ir s t ch eck th a t ra d io a c tiv e m a te ria ls have not been d is s e m in a te d in u n e x p e c te d d ir e c tio n s due, fo r e x a m p le, to ra p id flu c tu a tio n s in w ind d ir e c tio n. A ccurate delineation of the a re a s in which action to lim it ex p o su re of the public is re q u ire d m ust then r e s t on exam ination of all m a te ria ls which can be reg ard ed as contributing a sig n ificant ra d ia tio n d o se. T h ese m a te ria ls w ill v a ry accord in g to the type of a c tiv ity p re s e n t and to the m e d iu m in w hich it h a s been d is p e rs e d. G uidance on the p o ssib le ro u te s of e x p o s u re i s g iv en in s e c tio n 3.3. W h ere th e a p p e a ra n c e of a sig n ific a n t am ount of a c tiv ity in fo o d stu ffs, e tc. is lik e ly to be delayed, a s in the c a se of a re le a s e to the sea, delineation of the affe cte d a r e a m ay w ell re q u ire only a slig h t expansion of any ro u tin e su rv e y p ro g ra m m e w hich m ay be in o p eratio n. In o th e r c a s e s, s p e c ia l s a m p lin g m a y h a v e to be s ta r te d. M ilk m ay be singled out fo r sp e c ia l m ention sin ce u n der many c ircu m stan ces it is the foodstuff likely to be m ost w idely affe c te d. Som e m ilk s a m p le s m ay w ell have been tak en in the in itia l p h ase of the m o n ito rin g p ro g ra m m e but, a s explained in se c tio n (a), r e lia b le e s tim a te s of th e h a z a rd fro m th is so u rc e can be obtained only by w aiting fo r up to 24 h o u rs a f te r th e r e l e a s e. M ilk s a m p le s m a y n e e d to be c o lle c te d o v er a wide a re a but sp e c ia l atten tio n should be given to fringe a r e a s w ith a view to ex ten d in g o r c o n tra c tin g the a r e a o v e r w h ic h r e s t r i c tio n s m a y h av e b e e n im p o s e d on th e b a s is of g a m m a - s u r v e y r e s u lts. In g en eral, the subsequent su rv ey should provide data on in dividual nuclides ra th e r than on g ro ss activity, although rapid 41

54 sc re e n in g m ethods have th e ir value in the field, fo r exam ple, for determ ining w hether the 131I concentration in a m ilk sam ple is sufficient to w arrant its condem nation Following the trend of contam ination The predom inant h azard in the e a rly stag es follow ing an a c c id en t m ay be fro m re la tiv e ly s h o r t-liv e d n u c lid e s, su ch a s 1311, and em phasis w ill th erefo re be placed on the d eterm in a tio n of su c h n u c lid e s. A s r e s t r i c t i o n s o rig in a lly im p o s e d b e c a u se of the p re s e n c e of s h o r t-liv e d a c tiv ity a r e re m o v e d a s a re s u lt of the decay of th is activ ity, m e a su re m e n ts should e n s u re th a t r e s tr ic tio n s a r e not s till n e c e s s a r y in the m o re h ig h ly c o n ta m in a te d a r e a s b e c a u se of the p re s e n c e of longliv e d n u c lid e s. The su rv e y m ay have to be continued o v er an extended p erio d of tim e if all consequences of the accident a re to be thoroughly investigated. Thus, if a g ricu ltu ral land has been contam i n ated w ith lo n g -liv e d n u clid es, c ro p s su bseq u en tly grow n on th is land w ould re q u ire to be ex am in ed to e n su re th a t uptake of a c tiv ity fro m the s o il is not s ig n ific a n t. F u r th e r m o r e, sin c e m o v em en t of ra d io n u c lid e s th ro u g h th e s o il is s o m e tim e s v e ry slow, it m ay be n e c e s s a ry to m o n ito r fo r s e v e ra l y e a r s w a te r s u p p lie s em a n a tin g fro m u n d e rg ro u n d s o u r c e s if larg e am ounts of activity have been released into the ground M easu rem ent of in te rn a l d o ses A lthough the ra d ia tio n d o se s re c e iv e d by p e rso n s a s a re s u lt of in h a la tio n o r in g e stio n of a c tiv ity c a n be e s tim a te d fro m m e a su re m e n ts of co n cen tratio n s of rad io n u clid es in a ir, food and w a te r, a m o re a c c u ra te a s s e s s m e n t can be o b tain ed by m o n ito rin g re p re s e n ta tiv e m e m b e rs of the p u blic. M ethods in c lu d e w h o le-b o d y m o n ito rin g, m o n ito rin g of th e th y ro id g la n d follow ing r e le a s e of ra d io -io d in e and a n a ly s is of e x c r e ta. T h ese p ro c e d u re s should be im p lem en ted, to the ex te n t p ra c tic a b le, if th e r e is an y r e a s o n a b le u n c e rta in ty on th e e x p o su re re c e iv e d by m e m b e rs of th e p u b lic. 4 2

55 C ollection of scie n tific data V e ry little in fo rm a tio n i s a v a ila b le on th e b e h a v io u r of n u clides in the environm ent o r of the consequences of th e ir r e le a s e. T h e r e f o r e e v e r y re a s o n a b le o p p o rtu n ity sh o u ld be taken to m ake use of an accidental re lease as a source of m a t e r i a l fo r sc ie n tific s tu d ie s. E x p e rt ad v ice should be sought on th e w ay in w hich m e a s u r e m e n ts c a n be m a d e to p ro v id e th e m o s t u s e fu l in fo rm a tio n. M e a s u re m e n ts m a d e fo r th is p u rp o se a r e of c o u rs e su b o rd in a te to th o se m ade in o rd e r to a s s is t in p ro tectin g people fro m undue exposure. 43

56 6. EM ERGENCY MONITORING EQUIPM ENT* T he type and am o u n t of m o n ito rin g e q u ip m e n t w hich sh ould be held in re a d in e s s, o r w hich should be a v ailab le at sh o rt n o tice, fo r u se in e m e rg e n c y s itu a tio n s, w ill d epend on th e ty p e of a c c id e n ts which can be fo reseen and for w hich it is reaso n ab le to plan in ad vance. Many of the m e a su re m e n ts re q u ire d in an em ergency survey can be p e rfo rm e d u sin g in s tru m e n ts w hich a r e n o rm a lly a v a ila b le fo r ro u tin e w o rk w ith in an in s ta lla tio n. A ll in s tr u m e n ts in ten d ed fo r e m erg en cy u se should be ro b u st, re lia b le and sim ple to o p erate, and it is m ost im p o rtan t that they should be p erio d ically checked and kept in good w orking o r d e r. W hen d ecid in g on the n u m b e r of e ach type of in stru m e n t to be held in re a d in e s s fo r em erg en cy m onitoring c o n sid e ra tio n should be given to the p o ssib ility of lo s s of u se of in stru m e n ts owing to dam age o r contam ination during u se. The in stru m e n ts and equipm ent re q u ire d m ay be c la ssifie d in the following broad categ o ries: (a) In s tru m e n ts fo r d e te c tin g an a b n o rm a l r e le a s e of ra d io a c tiv e m a te r ia ls ; (b) In s tr u m e n ts fo r a s s e s s in g ra d ia tio n and c o n ta m in a tio n le v e ls (c) in the fie ld ; E quipm ent fo r collectin g sam p les and in stru m e n ts fo r a ssessin g th e ir radioactive content; (d) M iscellaneous ite m s, including equipm ent for tra n sp o rt, co m m unications, m eteoro lo g ical m easu rem en ts, p rotection of p e r so nnel and c o n tro l of a c c e s s I n stru m e n ts f o r d e te c tin g an a b n o rm a l r e le a s e o f r a d io a c tiv e m a te r ia ls, An a b n o rm al r e le a s e of ra d io a c tiv e m a te ria l m ay be detected by co n tin u o u sly o p e ra tin g m o n ito rin g d e v ic e s in s ta lle d a t the p o in ts of d is c h a rg e of g a seo u s o r liq u id e fflu e n ts. Owing to the re la tiv e ly high co n cen tratio n of rad io activ e m a te ria l which m a y be f o re s e e n a t th e s e p o in ts s im p le ra d ia tio n d e te c to r s c an be u se d. T he d e te c to r s should, w h en ev er p o ssib le, be coupled to c h a rt r e c o r d e r s in o rd e r to p ro v id e an in d icatio n of the ra te of re le a s e, and should be fitted with d ev ices which a c tiv a te an a la r m w hen the r a te of r e le a s e e x c e e d s p r e - # Inform ation on som e exam ples of m onitoring equipm ent is given in Annex VI. 4 4

57 d e te rm in e d v a lu e s. It is im p o rta n t th a t th e e q u ip m e n t sh ould be e x c e e d in g ly re lia b le in o p e ra tio n. M o n ito rin g d e v ic e s of th is type u su a lly fo rm a p a rt of the ro u tin e m o n i to rin g s y s te m s p ro v id ed fo r an in s ta lla tio n In stru m en ts to r a s s e s s in g radiation and contam ination le v e ls in the fie ld In s tr u m e n ts of th is ty p e a r e u su a lly r e f e r r e d to a s s u rv e y - m e te r s. T hey a r e u sed fo r m e a su rin g ra d ia tio n fie ld s p r o duced by distant so u rces o r for m easuring the radiation em itted by a ir-b o rn e o r d ep o sited contam ination. S u rv e y -m e te rs a r e d esig n ed e ith e r to m e a s u re e x p o s u r e - r a te s o r to re c o rd the n u m b er of im p u lse s p e r unit tim e produced in the d e te c to r. In stru m e n ts intended to m e a su re g a m m a -ra d ia tio n e x p o su re - ra te s usually use an ionization cham ber o r organic sc in tilla to r a s d e te c to r ; th e re s p o n s e m ay be in d ep en d en t of the gam m a photon en erg y o v er a wide ran g e, and hence they m ay be u sed fo r m e a s u rin g the to ta l g a m m a -ra y e x p o s u r e - r a te. The sen sitiv ity m ay, how ever, not be sufficient to allow a s s e s s m e n t of th e s ig n ific a n c e of th e g ro u n d d e p o sitio n of g am m a -ray em itting m a te rial. Instrum ents intended to m eas u re the im p u lse r a te u su a lly em ploy a GM c o u n te r o r in o r ganic s c in tilla to r a s d e te c to r. The re sp o n se m ay be m arkedly e n e rg y -d e p e n d e n t, but a v e ry high s e n s itiv ity is a tta in a b le P o rta b le su rv e y in s tru m e n ts P o rta b le s u rv e y in s tr u m e n ts a r e d e sig n e d to be c a r r ie d by hand and a re b a tte ry o p erated. The sen sitiv e elem ent m ay be an io n izatio n c h am b e r, a GM tube o r a sc in tilla tio n d e te c to r. C o u n te r-ty p e in s tru m e n ts p ro v id e q u a n tita tiv e a s s e s s m e n ts of g a m m a -ra y e x p o s u r e - r a te s only w hen th e y have been c a lib ra te d fo r sp e c ific g a m m a -e m ittin g ra d io n u c lid e s. In g e n e ra l a range of portable survey instru m en ts should be av ailab le fo r th e m e a s u r e m e n t of e x p o s u r e - r a te s fro m ab o u t m R /h up to a few R /h. I n s tr u m e n ts u s in g io n iz a tio n c h a m b e rs a r e u s u a lly d e sig n e d to m e a s u r e e x p o s u r e - r a te s o v e r th e ra n g e fro m ab o u t 1 m R /h to about 5 R /h o r m o re, but w ith sim p le m o d ific a tio n s the ra n g e c a n be ex te n d e d to m u ch h ig h e r e x p o s u r e - r a te s. I n s tr u m e n ts u sin g GM tu b e s are usually designed to cover the range from about 0. 02m R /h 4 5

58 to a b o u t 20 m R /h, o r fro m a b o u t c o u n ts /m in to ab o u t 105 c o u n ts/m in. In stru m en ts em ploying scin tillatio n co u n ters a s d e te c to r s u su a lly have s e n s itiv itie s w hich a r e one o rd e r of m agnitude o r m o re g r e a te r than those of in stru m e n ts e m ploying GM co u n te r tu b es. G re a t c a r e sh ould be ta k e n to p re v e n t th e c o n ta m in a tio n of p o rta b le su rv e y in s tru m e n ts d u rin g u se. If the le v e l of a i r borne contam ination is high, it is advisable to operate the in stru m en ts inside disposable thin plastic co v ers N on-portable survey instru m ents (a) V ehicle -borne instru m ents T h ese in stru m e n ts a r e b a sic a lly s im ila r to the c o rresp o n d in g p o rta b le in stru m e n ts; they m ay, how ever, be pow ered by c a r b a tte r ie s o r by m o b ile g e n e ra to rs. T he se n sitiv ity re q u ire d is s im ila r to th a t r e q u ir e d fo r p o rta b le in s tr u m e n ts. T he d e te c to r is often co n n ected to a c h a rt r e c o r d e r and o p e ra te d c o n tin u o u s ly. A s c in tilla tio n d e te c to r c o u p le d to a t r a n s p o rta b le p u ls e -h e ig h t a n a ly s e r p ro v id e s a ra p id m eth o d fo r id e n tify in g g a m m a -e m ittin g ra d io n u c lid e s. It m ay be d e s i ra b le to m ount th e d e te c to r on th e end of a f a ir ly long pole fix ed o u tsid e th e v e h ic le a s the d e p o sitio n on ro a d s u rfa c e s m ay not be ty p ic a l of th e g e n e ra l g ro u n d d e p o sitio n and th e v e h ic le its e lf m a y be sig n ific a n tly c o n ta m in a te d. (b) In s tr u m e n ts fo r a e r i a l s u rv e y s S u rv e y in s tr u m e n ts, p e rh a p s c o u p led to a c h a r t r e c o r d e r, m a y be m o u n ted in a fix e d -w in g a i r c r a f t o r h e lic o p te r fo r th e p u rp o se of p e rfo rm in g a ra p id co n tin u o u s s u rv e y of the le v e ls of r a d ia tio n e m itte d by a i r - b o r n e o r d e p o s ite d m a t e r i a l. A fix e d -w in g a i r c r a f t s u rv e y i s u s u a lly p e rfo rm e d a t a h eight of about 200 m e tre s. At th is height the ra d ia tio n le v e l fro m g ro u n d -d e p o site d m a te r ia l m ay be v e ry low ; fo r exam ple, the in c re ase d co u n t-rate produced by a ground d e p o sitio n of 0.4 /j Ci / m2 of 131I m a y be of th e sa m e o r d e r of m agnitude a s the v a ria tio n s in c o u n t-ra te a ttrib u ta b le to d iffe re n t g eo lo g ical fo rm a tio n s. It is n e c e s s a ry, th e re fo re, to u se a d ete cto r of the highest sen sitivity, such a s a larg e in - 4 6

59 o rg an ic c ry s ta l s c in tilla to r capable of m e asu rin g g a m m a -ra y le v e ls of the o rd e r of m R /h. Since h e lic o p te rs can ope r a te a t low sp e e d s and c lo se to the g ro u nd, s ta n d a rd p o r ta b le s u r v e y - m e te r s m ay be u se d. (c) F ix e d m o n ito rin g in s tru m e n ts T he fixed m o n ito rin g in s tru m e n ts w hich a r e so m e tim e s u sed fo r co ntinuous ro u tin e m o n ito rin g in the neighbourhood of an in s ta lla tio n c a n p ro v id e a d d itio n a l in fo rm a tio n on ra d ia tio n and co n tam in atio n le v e ls o c c u rrin g in e m e rg e n c y c o n d itio n s. F o r th is p u rp o se fixed m o n ito rin g in s tru m e n ts m u st be c a p ab le of m e a s u rin g the high le v e ls e x p e c te d in e m e rg e n c y s itu a tio n s. (d) O th e r in s tru m e n ts P o rta b le and tra n s p o rta b le, sin g le -c h a n n e l and m u lti-c h a n n e l g a m m a - s p e c tr o m e te r s (se e s e c tio n ) c a n p ro v id e i n form ation v ery rapidly on the com position of m a te ria l deposite d on th e g ro u n d w ith o u t th e n e c e s s ity of ta k in g s a m p le s. T h e m o re c o m p lic a te d in s tr u m e n ts r e q u ir e to be o p e ra te d by p e rs o n n e l w ith ad e q u a te know ledge and th e r e f o r e can n o t e n tir e ly r e p la c e th e s im p le in s tr u m e n ts d e s c r ib e d a b o v e E quipm en t fo r c o lle c tin g s a m p le s and in stru m e n ts fo r a sse ssin g th eir ra dio active contam ination Sam pling B a tte ry -o p e ra te d p o rta b le a i r s a m p le rs m ay be u sed fo r a s s e s s in g the co n ta m in atio n of the a i r at se le c te d p o in ts. F o r p a rtic u la te m a te ria ls a known volum e of a i r is draw n through a f ilte r p a p e r on w hich the p a rtic u la te m a te ria l is d eposited. F o r g aseo u s m a te ria ls, c a rb o n c a rtrid g e s o r o th e r sp ecially desig n ed plugs of a b so rb e n t m a te ria l m ay be used to tr a p the c o n ta m in a tin g m a te r ia l. S p e c ia l d e v ic e s m a y be u s e d fo r tra p p in g io d in e and th u s a r a p id a s s e s s m e n t m ay be m a d e of th e c o n c e n tra tio n of 131I in th e a tm o s p h e re. 47

60 S a m p le s of w a te r, m ilk and o th e r liq u id s m ay be c o lle c te d by sim p le dipping d e v ic e s. T h e s a m p le s should be p laced in con tam in atio n -free, w ell-stoppered g la ss o r p lastic b ottles. It may be n e c e s s a ry to add sm a ll quantities of a p reserv ativ e such a s F o rm a lin, to m ilk. If s tra tific a tio n is to be studied it w ill be n e c e s s a ry to obtain sa m p le s of s o il by using a conven tio n al c o r e cu ttin g d e v ice. G r a s s and o th e r s im ila r ty p e s of v e g e ta tio n m ay be cu t by hand c lip p e r s. The g r a s s should be held w hile b eing cu t in o r d e r to p rev en t its b eing contam in ated by the s o il. It m ay be n e c e s s a r y to sam ple o th er m a te ria ls, fo r exam ple fish, sea-w eed and o y ste rs, and sin ce the value of the re su lts o b tained depends en o rm o u sly on the c a r e w ith w hich the sa m p les a re co lle cte d, the ad vice of e x p e rts should be obtained on sp e cia liz e d sam pling tech n iq u es. Solid sam p les should be placed in clean paper o r p la stic bags w hich should then be sealed with adhesive tape. A ll sa m p le s should be c le a r ly la b e lle d a s to d ate, and tim e and lo catio n of co lle c tio n. G reat c a re should be taken at a ll tim e s to prevent cro ss-co n ta m in a tio n of sam p les during c o l lectio n, packaging and tra n sp o rt. A dditional equipm ent m ay be re q u ired fo r the tre a tm e n t and c h e m ic a l a n a ly s is o f s a m p le s p r io r to the m e a s u re m e n t of th e ir ra d io a c tiv e co n ten t. In fo rm a tio n on the equ ip m ent needed and on the ap p ro p riate m ethods of c h e m ic a l a n a ly sis is av a ila b le in a num ber of r e p o r ts M easu rin g in stru m en ts The ra d io a ctiv e content of the c o lle c te d sa m p les m ay be a s s e s s e d by using standard counting equipm ent. 4 See in particu lar: [ 1 ] W orld H ea lth O rg a n iz a tio n, M ethods o f ra d io c h e m ic a l a n a ly s is, T e c h n ic a l Reports S e rie s No , Report o f a Jo in t W HO/FAO Expert C o m m itte e. (A rev ised e d itio n o f this d o cu m en t in th e form o f a Jo in t WHO/FAO/IAEA S c ie n tif ic C o m m itte e w ill b e issued in ). [ 2 ] U n ited S ta te s A to m ic Energy C o m m issio n, M an u al o f Standard P ro ced u res, N Y O ( R e v.), H ealth and Safety Laboratory. 4 8

61 T he id e n tific a tio n and a s s a y of in d iv id u al a lp h a -e m ittin g and b e ta -e m ittin g ra d io n u c lid e s in a sam p le u su a lly re q u ir e s the p re lim in a r y c h e m ic a l s e p a ra tio n of the s u b s ta n c e s p re s e n t. S pecial ra p id p ro c e d u re s have been developed fo r som e of the ra d io n u c lid e s of p a r tic u la r in te r e s t in an e m e rg e n c y su rv e y. C e rta in g a m m a -e m ittin g ra d io n u c lid e s su ch a s i31i and 131Cs m ay be ra p id ly id e n tified and a ssa y e d by u sin g a g a m m a -ra y s p e c tr o m e te r c o n s is tin g of a s c in tilla tio n d e te c to r c o u p led to a m u lti-c h a n n e l p u ls e -h e ig h t a n a ly s e r s. S am p le m e a s u r in g in s tr u m e n ts m ay be o p e ra te d in a la b o r a to r y in c o n ta m in a tio n -fre e re g io n o r in a m o n ito rin g v e h ic le. If th e y a r e m ounted in a v e h ic le it m ay be n e c e s s a r y to p ro v id e th e m w ith b a c k g ro u n d c o m p e n s a tin g d e v ic e s and to a v o id c o n ta m in a tio n of the e q u ip m e n t by k e e p in g the a i r - p r e s s u r e w ith in the v e h ic le slig h tly ab o v e a tm o s p h e ric p r e s s u r e and by filte r in g in c o m in g a i r M is c e lla n e o u s e q u ip m e n t T r a n s p o r t eq u ip m en t A n u m b e r of s u rv e y v e h ic le s sh o u ld be a v a ila b le in w hich radiation m easuring instru m ents and sam ple collecting equipm ent m ay be c a r r ie d. It is advan tageous fo r the v e h ic le s to be p re p a re d fo r the in sta lla tio n of ad d itio n al equipm ent, such a s d e v ic e s fo r th e e s tim a tio n of g r o s s b e ta -a c tiv ity of s a m p le s and p o s s ib ly a m o b ile g a m m a - s p e c tr o m e te r. T hey should also c a rry pow er supplies for any equipm ent that can not be o perated on b a tte rie s. The vehicles should be re aso n ably sm a ll and should be cap ab le of tra v e rs in g c o m p arativ ely rough g ro u nd. F o u r-w h e e l d riv e is reco m m en d ed. E m e rg e n c y e n v iro n m e n ta l c o n d itio n s c a n c r e a te a n e e d fo r e x tr a v e h ic le s s u b s ta n tia lly in e x c e s s of th e n o r m a l c o m p le m e n t. P r i o r a r r a n g e m e n ts sh ould be m a d e w ith o u tsid e s o u rc e s w h ere su ch v e h ic le s could be m ade re a d ily a v ailable. O r d in a r y v e h ic le s m a y be u s e d to s u p p le m e n t th o s e m a in ta in e d s p e c ia lly fo r s u rv e y w o rk by a rra n g in g th a t, fo r ex - 5 S e e A n n ex V fo r a d iscu ssion o f so m e s p e c ia l a n a ly t ic a l co n s id e ra tio n s w ith re g a rd to em ergen cy environ m en tal m onitoring. 49

62 am ple, m o n ito rin g equipm ent can e a s ily be in sta lle d at sh o rt n o tic e. A n e m e rg e n c y k it s u ita b le f o r t r a n s p o r t in an o r d in ary vehicle and a typical, sp ecially equipped, su rv ey v e h ic le a r e show n in F ig s FIG. 2. Contents of em ergency environm ental monitoring kit (Hanford Project - USA) A s sta te d in sectio n the u se of a ir c r a f t o r boats m ay be indicated under sp ecial conditions. It is probably b est to a r ra n g e fo r b o a ts o r h e lic o p te rs to be m ade a v a ila b le a t s h o rt 5 0

63 FIG. 3. Layout o f instrum ents w ithin em ergen cy m onitoring v eh icle (Atom ic Energy Commission - Denmark) notice under co n tract with outside so u rces. Such an a rra n g e m ent is le s s p ra c tic a b le w ith fixed-w ing a ir c r a f t, into w hich sp ecial equipm ent m ay have to be in stalled. 6,4. 2. C om m u n icatio n s and w arn in g equipm ent The ra p id tr a n s m is s io n of in fo rm a tio n o r in s tru c tio n s is of g re a t im p o rta n c e. The em e rg e n c y c o n tro l c e n tre should have p rio r ity telephone lin e s a t its d is p o s a l fo r th e tr a n s m is s io n of m o n ito rin g and o th er inform ation. Owing to the fact, how ever, that the m o n ito rin g te a m s m a y be d is p e r s e d on th e g ro u n d o r m a y be o p e ra tin g in a i r c r a f t, s h o rt-w a v e ra d io -c o m m u n ic a tio n h a s m any a d v a n ta g e s and should be a v a ila b le fo r c o n ta c t betw een team s o r individuals engaged in m onitoring task s and the cont r o l c e n tr e. It i s a d v is a b le th a t m o s t, if n o t a ll, r a d i o c o m m u n ic a tio n s e ts sh o u ld be p o w e re d by b a t te r ie s o r by indep en d en t v e h ic le -b o rn e p o w er su p p lie s. "W a lk ie -ta lk ie " type se ts can conveniently be used. 51

64 FIG. 4. Layout o f instrum ents w ithin em ergen cy m onitoring v eh icle (A tom ic Energy C o m m i s s i o n - Denm ark) If p o ssib le, it is ad visable to a rra n g e fo r the ta p e -re co rd in g of telephone com m u n ication s. In any event, m e ssa g es should be "logg ed " in som e sy stem a tic fashion M eteoro lo g ical equipm ent The standard equipm ent of a cu sto m ary s m a ll m e te o ro lo g ical station (b a ro m ete r, th e rm o m e te r, h y g ro m eter, and, in p a r 5 2

65 tic u la r, w in d -sp eed m e te r) is re q u ire d in o rd e r to g et lo c a l inform ation at points rem o te fro m fixed m ete o ro lo g ical s ta tio n s. In th e c a s e of l a r g e r e s ta b lis h m e n ts, fo r e x a m p le th o se contain in g pow er r e a c to r s and re p ro c e s s in g p la n ts, it is a d v isa b le to in s ta ll a s m a ll m e te o ro lo g ic a l sta tio n ort the site fo r the p rin c ip a l p u rp o se of d eterm in in g w here and when s a m p le s sh o u ld be c o lle c te d an d m e a s u r e m e n ts sh o u ld be m a d e P r o te c tiv e e q u ip m e n t M onito rin g te a m s should be p ro v id e d w ith a p p ro p ria te p r o te c tiv e equipm ent to e n su re th e ir safety, fo r exam ple m a sk s, hoods, o v eralls, shoes, gloves, etc. and also p erso n nel m o nitoring devices (dosim eters, film badges, alarm dosim eters) W arning and control equipm ent S tan d ard ite m s such a s w arn in g sig n s, te m p o ra ry b a r r i e r s, ro p e s, e tc. w h ich a r e n e e d e d fo r th e d e m a rc a tio n o f th e b o u n d a rie s of c o n ta m in a te d a r e a s, sh o u ld be k ep t in s to c k and e a s ily a v a ila b le. 5 3

66 INTRODUCTION TO ANNEXES The following annexes a re intended to be of help in the developm e n t and a p p lic a tio n of th e e n v iro n m e n ta l m o n ito rin g p r o c e d u r e s d e s c rib e d in th e m a in te x t. It is e m p h a siz e d once a g a in th a t th e techniques and p ro c e d u re s outlined should be co n sid ered as exam ples only and th a t th e ir a p p lic a b ility m u st be ju d g ed in th e lig h t of the p re v a ilin g c irc u m s ta n c e s. T he co n tent of the an n ex es h as been co m p iled o r d e riv e d fro m p u b lish e d m a te r ia l o r fro m m a te r ia l p ro v id e d by in d iv id u a l p a n e l m e m b e rs and re p re s e n ta tiv e s of the o th e r p artic ip atin g in tern atio n a l o rg an iz atio n s. The annexes have not been review ed by the com plete panel and it should th e re fo re not be a ssu m e d th a t the indiv id u al m e m b e rs of the p a n e l n e c e s s a r ily a g re e w ith, o r c a r r y any re s p o n s ib ility fo r the in c lu s io n of, a ll th e m a te r ia l w hich is p re s e n te d. A N NEX I IN V EN TO R IES O F FISS IO N -PR O D U C T S AND PO SSIBLE RELEA SES (T a b le s I ) 5 4

67 TABLE I. 1 C A L C U L A T E D A C T IV IT IE S O F SO M E IM P O R T A N T F IS S IO N -P R O D U C T S IN URANIUM * R E A C T O R F U E L (D e riv e d fro m d a ta p r e s e n te d in R e fs, [ l, 3]) Fission -product A c tiv itie s a t th e en d o f various o p e ra tin g p eriod s (k C i/ M W (t)) A c t iv it ie s a t th e end o f v ario u s sh ut-d ow n p erio d s fo llo w in g o p e ra tio n fo r 1 yr (k C i/ M W (t)) O perating period Shut-dow n period d 1 yr 5 yr 7 d 3 0 d d 85K r K r Sr S r R u + 106Rh j zT e j X e C s Ba C e + 144Pr v T h is ta b le a p p lie s to n a tu ra l u ra n iu m, b u t fo r th e purpose o f e s tim a tin g th e a c t iv it ie s o f fissio n -p ro d u c ts w h ic h m ig h t b e released in an a ccid e n t it can be applied to enriched uranium.

68 O l 05 TABLE 1.2 VOLATILE RELEASE OF FISSION-PRODUCTS FROM URANIUM* REACTOR FUEL CALCULATED ACTIVITIES OF SOME IMPORTANT FISSION-PRODUCTS RELEASED (Derived from data presented in Refs. [2, 3]) Fission-product Percentage of fission-product in fuel assumed to be released Activities released at the end of various operating periods (kci/mw(t)) Activities released at the end of various shut-down periods following operation at full power for 1 yr (kci/mw(t)) Operating period Shut-down period 100 d 1 yr 5 yr 7 d 30 d 100 d 85 Kr Kr S r S r losru+ I06Rh j Te j Xe Cs Ba Ce + 144Pr * This table applies to natural uranium, but for the purpose of estimating the activities of fission-products which might be released in an accident it can be applied to enriched uranium. Note: This table indicates the approximate activities of fission-products released from the fuel. The interplay of many factors, for example plating-out and containment, would undoubtedly reduce the activities of the fission-products actually released to the environment.

69 TABLE I. 3 V O L A T IL E R E L E A S E O F F IS S IO N -P R O D U C T S F R O M U R A N IU M * R E A C T O R F U E L C A L C U L A T E D A C T IV IT IE S O F SO M E IM P O R T A N T F IS S IO N -P R O D U C T S R E L E A S E D AS P E R C E N T A G E S O F T H E A C T IV IT Y O F T H E 131I R E L E A S E D Activities released as percentage of Fission-product Percentage of fission-product in fuel assumed to be released Activities released as percentage of ill! released at the end of various operating periods released at the end of various shut-down periods following operation at full power for 1 yr Operating period Shut-down period 100 d 1 yr 5 yr 7 d 30 d 85 Kr Kr Sr Sr MR u + 1MRh j Te j Xe Cs Ba * C e+1mpr $ This cable applies to natural uranium, but for the purpose of estimating the activities of fission-products which might be released in an accident it can be applied to enriched uranium. Note: This table refers to the activities of fission-products released from the fuel. The interplay of many factors, for example plating-out and containment, would undoubtedly alter the relative activities of the fission-products actually released to the environment.

70 TABLE I. 4 CALCULATED MEAN ACTIVITIES OF SELECTED RADIONUCLIDES RELEASED FROM PREVIOUSLY UNIRRADIATED URANIUM METAL FOLLOWING; (a) a c ritic a lity e x c u rsio n w ith a to ta l energ y re le a s e of 100 MWs (3 XlO18 fissio n s) w ith im m e d ia te p re fe re n tia l re le a s e of v o la tile fis s io n -p ro d u c ts (assu m ed tim e of r e le a s e m in*) (b) an e x c u rsio n w ith a to ta l e n erg y re le a s e of 300 MWs (1019 f is sio n s) w ith m elt-d ow n, oxidation and slow p re fe re n tia l re le a s e of v o la tile fissio n -p ro d u c ts (assu m ed m ean tim e of re le a s e 2.4 h*) (c) a spike e x c u rsio n of to ta l m agnitude 1020 fissio n s re su ltin g in com p lete v a p o riz a tio n of the sy ste m and im m e d ia te re le a s e of a ll fissio n -p ro d u c ts (assum ed m ean tim e of re le a s e m in*) N uclide H a lf-life Assumed percen tage release ((a ) and (b ) only) (a) A ctiv ity released (C i) (b) (c) «B r 2. 4 h I X x x 1 0 * ttm Kr 1.9 h X l O ' x X 1 0 w Kr 3. 2 m in X 1 0 * x lo 4 «K r 33 s x l 0! x 1 0 s Rb IS m in x 1 0 * x Rb 2. 9 m in x 1 0 * x 1 0 s #,Rb 100 s X 1 0 * x * lm Rb 14 m in x 1 0 * 6.9 x X 1 0 * " R b 5.3 s X l O ' x 10 " S r 53 d x l 0 ' s 1.7 x lo " " S r 2 8 yr X X 1 0 'S 9. 6 x * Sr 9. 7 h x 1 0 -* 2. 4 X 1 0 ' X 1 0 s Sr 2. 7 h X 1 0 " 1 6. Ox 1 0 "1 1.1 X lo 4 10<Ru i v x 1 0 "* 1.2 x lo * X 1 0 * 1 lotru 4 min XlO 3 i 3 i m je 30 h X x 1 0 * 3.9X10 m T e 25 min X X x 1 0 s *T e h x ' x 1 0 * u s m je 63 min X X x u it e 2 min X 1 0 * 7.7x x lo 4 m T e 42 min x 1 0 * 6. 5x X104 m i 8.1 d x * u s, 2. 3 h x 1 0 * lss. l «i 135, IWj h Ox X 1 0 * 53 m in X x 1 0 * 1.0X h X x X s x 1 0 * x 1 0 s U7Xe 3. 9 min X 10* xlo 5 140X e 16 s x x l O 3 w C s 30 yr X * 1. 4 x 1 0 '* 5. 0 x 1 0 ' * M«CS 66 s X 1 0 * x 1 0 s ^ B a d 0.2 X 00 o 2. 1 x 1 0 "* 9. 7 x 1 0 M1Ba 18 min x 10"* 8. 7 x lo 4 MIBa 6 m in x x 1 0 s C e d x 1 0 '< 5. 5 x l O " C e m in x 1 0 " * 6. 4 X lo 4 * The times chosen are for convenience in using the published data of Glendenin cited in Bolles, Ballou [4]. Note: The interplay of many factors, for example plating-out and containment, would undoubtedly reduce the activities of die radionuclides actually released to the environment 58

71 ANNEX II AIR-BORNE RELEASES: DISPERSION, DEPOSITION AND DOSE-EXPOSURE RELATIONSHIPS* B e cau se of the im p o rta n c e of the a tm o sp h e ric ro u te of re le a s e to th e e n v iro n m e n t c o n s id e ra b le e ffo rt h a s b een g iv en to the stu d y of the d isp e rsio n of a ir-b o rn e m a te ria l. S everal th e o retical diffusion m o d e ls h av e b e e n d e v e lo p e d and d is p e r s io n p a tte r n s in sp e c ifie d w e a th e r co n d itio n s, b a se d on th e s e m o d e ls, have b een p u b lish e d (R efs. [2, 5-7 ]). F r o m th e se p a tte r n s it m a y be p o ssib le to obtain e a r ly e s tim a te s o f the co n ta m in a tio n p a tte rn follow ing a re le a s e of fis s io n -p ro d u c ts to the a tm o s p h e re and to u se th e se e s tim a te s a s a b a sis fo r the selectio n of im p o rtan t sam pling locations. E s tim a te s of th e tim e - in te g r a l of c o n c e n tra tio n of a ir - b o r n e m a te ria l at ground lev el, b ased on one of the th e o re tic a l m odels [7], a r e p re s e n te d in F ig s. II. 1 (a -d ). E s tim a te s of the ground d e p o sitio n m a y be d e riv e d r e la tiv e ly sim p ly fro m th e s e c u r v e s. T h e se d ia g ra m s a r e inten d ed only to illu s tr a te som e of the p o ssib le types of d is p e rs io n. P a tte r n s a p p lic a b le to the lo c a l w e a th e r conditions at the tim e of re le a se should be d erived as a b asis fo r rea listic e s tim a te s. M ethods of doing so a r e d e sc rib e d in R efs. [2, 5-7] and in o th er publications liste d in the bibliography. It m u st be e m p h a siz e d th a t e s tim a te s of c o n c e n tra tio n and d e p o sition d eriv ed fro m th e o re tic a l diffusion m odels a re not in any way a su b stitu te fo r effe ctiv e e n v iro n m e n ta l sam p ling and m e asu rem en t te c h n iq u e s. F ig s. I I * S o m e in fo rm a tio n o f th e se and o th e r re la te d to p ic s w ill be found in T a b le s II. 1-6 and 59

72 TABLE II. 1 [8] E S T IM A T E D A C T IV IT Y IN M IL K (mc i / l i t r e ) FO L L O W IN G AN IN IT IA L T O T A L D E P O S IT IO N O F 1 M C i/m 2 O F TH E IN D IC A T E D N U C L ID E S (A llow ing f o r d e c a y of h e rb a g e w ith h a lf - tim e of 14 d) D ays a fte r d e p o sitio n I 132 X e 8SSr 30 Sr 140 Ba i C sa a Using unpublished in form ation from Dr. B.F. Sansom. N o te : T h e e s tim a tio n s in c lu d e th e assu m p tio n s th a t 2 5 % o f a c tiv ity is re ta in e d on ed ib le herbage and th at th e cow grazes an area o f 160 m 2 a day. 60

73 TABLE II. 2 [8 ] E S T IM A T E D A C T IV IT Y IN EG G S FR O M F R E E -R A N G E HENS (IN n C i/e G G ) FO L L O W IN G AN IN IT IA L T O T A L D E P O S IT IO N O F 1 ju C i/m 2 O F TH E IN D ICATED NUCLID ES D ays a fte r 131 [ a 89 S r'3 90S rb 137 C s d e p o sitio n W h o le eggd W h o le egg E d ib le p art W h o le eg g E d ib le part W h o le e g g a D eriv ed by G arn er fro m d a ta g iv e n b y O k o n sk i, L e n g e m a n n, C o m a r [ 9 ], b D e riv e d b y G a rn e r fro m d a ta g iv e n by C o m a r, D rig g ers [ 1 0 ], c D eriv ed b y G arn er fro m d a ta g iv e n by E k m an [ 1 1 ]. d S h e ll c o n ta in s in s ig n ific a n t am o u n ts o f n u c lid e. 61

74 TABLE I I. 3 DOSE-RATE IN AIR AT A HEIGHT OF 1 m ABOVE UNIFORMLY DISTRIBUTED GAMMA-EMITTING FISSION-PRODUCTS ON THE GROUND* Gamma-emitting nuclide Dose-rate for 1 Ci/m2 (rad/h) 9sZr + 9smNb Nb Ru Ru Rh 2, j Cs Ce Ce 0.34 # Derived from data presented by Mahmoud [ 12]. TABLE II. 4 DOSE-EXPOSURE RELATIONSHIP EXTERNAL GAMMA-RADIATION FROM AIR-BORNE MATERIAL* Material Whole-body dose Time-integral of concentration in air (Ci-sec/m3) Total gaseous and volatile 1 rad (gamma) 3.8 (related to time of release) or fission-products 0.8 (measured at one days decay) * Derived from data given by Beattie [2], Note: The derived provisional relationships between radiation dose and time-integral of concentration in air, concentration in milk, deposition on pasture and on green vegetables presented in Tables II. 4, II. 5 and II. 6 are intended merely to be of help in selecting monitoring techniques of adequate sensitivity for the measurement of contamination levels corresponding to the applicable emergency dose limits. The appropriate publications should be consulted for more precise and possibly more up-to-date information on those'relationships. 62

75 TABLE II. 5 DOSE-EXPOSURE RELATIONSHIPS INHALATION OF RADIOACTIVE MATERIAL Nuclide C ritical organ Age Dose or dose-rate to critical organ Corresponding intake (MCi) Corresponding tim e-integral of concentration in air (Ci*sec/m8)a isijb Thyroid 0 1 rad X 10* 5 6 months 1 rad x10 '* 1 yr 1 rad X 1 0 '* Adult 1 rad X Srb Bone (at site of 0 1 rad X 10 "3 maximum 6 months 1 rad X 10 ~3 concentration) ly r 1 rad x 10 "s Adult 1 rad X 10 ~2» Srb Bone (at site of 0 1 rad/yr x l O '4 maximum 6 months 1 rad/yr X 10 ' 4 concentration) 1 yr 1 rad/yr x 1 0 *4 Adult 1 rad/yr X 1 0 '* 'Csb Whole body 0 1 rad x 10 ~z 6 months 1 rad x lo '2 1 yr 1 rad X 1 0 *2 Adult 1 rad 15,0 6.5X 10 ' 2 Fission-product Thyroid 3 yr or less 1 rad 2.8X 10 * iodine Tec Adult 1 rad 1.2 x 1 0 ' 3 (in terms of 131I at one day) 106Ruc G. I. tract 1 rad 3.2X10 * Ba (sol. )c Bone Adult 1 rad 2.1 X 1 0 w0ba (insol. )d Lungs Adult 1 rad 2.9x 10 *2 144 Ce (sol. )c Liver Adult 1 rad 1.7 x 1 0 *3 l44ce (insol. )d Lungs Adult 1 rad 4.2X 10 *3 226 Ra (sol.)d Bone Adult 1 rem/yr 5.0 x 1 0 ' 4 239Pu (sol.)^ Bone Adult 1 rem/yr 2.9x 10 *s a To obtain the permissible emergency "lim its" recommended by the Medical Research Council, applicable to members of the general public, the figures given in column 6 above should be multiplied by the recommended maximum permissible doses or dose-rates to the critical organs, which are: thyroid ( 1SII) - 25 rads, bone (**Sr) - 15 rads, bone ( 90Sr) rad/yr, whole body ( l37cs) - 10 rads. b Data derived from report to the Medical Research Council by its Com m ittee on Protection Against Ionising Radiations [15]. c Derived from data presented by Beattie [2 ], d Derived from data presented by Cook [14]. 63

76 TIME-INTEGRAL Of CONCENTRATION AT GROUND LEVEL IN Ci-sec/m3 PER CURIE RELEASED FIGjJI. 1. Atmospheric dispersion from a point source (Redrawn from curves presented in Ref. [7]) v^/uo = deposition coefficient u0/ujj = wind speed shear (a) Release height: (b) Release height:...ground level...ground level m m Wind speed at release height: 1 m/s Wind speed at release height; 1 m/s Atmospheric condition: moderately stable Atmospheric condition: very stable 64

77 TIMEHNTEGRAL OF CONCENTRATION AT GROUND LEVEL IN Ci-sec/m J PER CURIE RELEASED FIG. II. 1. Atmospheric dispersion from a point source (Redrawn from curves presented in Ref. P]) v^/uj = deposition coefficient uj/ujj = wind speed shear (c) Release height: ground level 70 m Wind speed at release height: 10 m/s Atmospheric condition: moderately stable (d) Release height: ground level m Wind speed at relase height: 10 m/s Atmospheric condition: very stable 65

78 TABLE II. 6 D O S E -E X P O S U R E R E L A T IO N S H IP IN G E S T IO N O F R A D IO A C T IV E M A T E R IA L (a) I n g e s t i o n in m i l k Nuclide Critical organ Age Dose or dose-rate to critical organ Corresponding concentration in milk (peak levels)3 Corresponding initial deposition on pasture (see Table II. 1) (Ci/mz) lsijb Thyroid 0-6 months 1 rad 3 yr 2.6 x lo '1 iici/litre 1.2 x i o '1 1.7 xlo "8 MSrb ' Bone (at site of maximum concentration) All ages 1 rad 1.3X10"* jici/g Ca 8 x l0 7 s0srb Bone (at site of maximum concentration) All ages 1 rad/yr 1.3X 10" lici/g Ca 8X10"* ' Csb Whole body 0 1 rad 6 months 1 rad.adult r-' 1.5 x 1 0 "' (JCi/lilre 1.5X 10" 7 xlo *8 7 x lo "8 (b) I n g e s t i o n i n g r e e n v e g e t a b l e s Nuclide Critical organ Dose or dose-rate to critical organ Corresponding deposition on green vegetables (tentative estimates) (Ci/m l) 131jC Thyroid 1 rad 2 X 10"6 90Sr Bone 1 rad/yr 2 X 10"' 137Cs Whole body 1 rad 1 x 10 5 a To obtain the permissible emergency "limits" recommended by the Medical Research Council, applicable to members of the general public, the figures given in column 5 for concentrations in milk should be multiplied by the recommended maximum permissible doses or dose-rates to the critical organs, which are: thyroid ( IS1I) - 25 rads, bone (^ Sr) - 15 rads, bone <»<>Sr) rad/yr,. whole body P 81Cs) -1 0 rads. b Data (excluding that given in the last column) derived from report by the Medical Research Council by its Committee of Protection Against Ionizing Radiations [1 6 ]. c Derived from data provided by Beattie [2 ].

79 u p i i i i i i i i i i os FIG. II. 2. Estimated activity in milk following an initial deposition on herbage of 1 jici/m2 of the indicated nuclides TIME AFTER DEPOSITION ( d j FIG. II. 3. Estimated activity in eggs from free-range hens following an initial deposition of 1 jici/m2

80 FIG. II. 4. Exposure-rate in air above infinite plane source of gamma-emitters [13] 68

81 A N N E X III A L P H A -, B E T A - A N D G A M M A -R A D IA T IO N S U R V E Y S Radiation surveys, particularly gam m a-radiation surveys, are of value for the rapid determ ination of the extent of d isp ersal of radioactive contamination on the ground or in surface w ater. Although the presence of alpha- and beta-emitting nuclides can be detected without sampling, for any quantitative assessm ent of the amounts present sampling is necessary. Suitable methods are described in Annex IV. 1. A lp h a -ra d ia tio n s u r v e y s The detection lim it for alpha-em itters on the ground using the A m erican "Scintillation Portable Poppy" or sim ilar instrum ents such as the B ritish Type 1320 alpha-probe (see Annex VI) is about 10'2 ^C i/m 2. This corresponds to an air exposure of approximately 2X10"5 C i-sec/m 3 or an average one-hour a ir concentration of the order of 10'9 /uci/cm3. Air concentrations of alpha-em itters of this magnitude are difficult to generate and in all probability there will not be sufficient alpha-contamination on the ground to warrant surveys except in the im m ediate vicinity of an accident involving large quantities of an alpha-em itter. 2. B e ta -ra d ia tio n s u r v e y s Depending on the radionuclides involved, a direct ground survey may p resent a m ore sensitive m easure of the probable vegetation contamination level than analysis of samples removed from the field as described in Annex IV. Conversion of ground survey readings to vegetation contam ination levels can be accom plished by use of the following equations and factors: (a) A portable GM su rv ey-m eter calibrated to yield 3000 to 4000 counts/min per mr/h of Ray is used. Suitable instruments are described in Annex VI. (b) The probe is held at not m ore than 5 cm above the ground with the beta-shield open. (c) 100 counts/m in can be detected above a norm al 50 to 100 counts/m in background. 69

82 (d) Readings are taken in open terrain not in close proximity to heavy vegetation cover or buildings. (1) D = RXF where D= ground deposition in ;uci/m2, R = GM m eter reading in units of 102 counts/min (background corrected), F = factor from Table III. 1. TABLE III. 1 GROUND SURFACE CONTAMINATION L E V E L S* OF VARIOUS NUCLIDES REQUIRED TO YIELD 100 counts/min (NET) ON A GM M ETER (OPEN WINDOW) Nuclide F ((ici/m2 per 100 counts/min) 95Z r+ 95Nb 6 141Ce 2 i03mruj mixed Ru Rh (100 d old)a 1 60Co, Sr, 9»Sr, 90Y, S1Y. Cs, Ba, 14«La 144Ce Pr, 106Ru+ 106Rh, mixed radioiodines (1 h to 1 week old). 0.3 mixed fission-products (100 d old) > * Level varies with background readings, ground roughness and vegetation cover. a Age refers to time since irradiation of the fuel from which the FP's were released. (2) C=(DXf)/d where C vegetation concentration in n Ci/kg, D ground deposition in /uci/m2. d density of vegetation cover in kg/m2, f = fraction of deposited nuclide which is on the vegetation. f ranges from 0.1 to 1 and is usually taken to be for 131I in the United Kingdom. 70

83 3. G a m m a -r a d ia tio n s u r v e y s G round su rv e y s Although gamma-radiation surveys may be needed to define contaminated areas from which evacuation of people may be demanded, perhaps their most important role is the prediction of levels of contamination likely to be found in some foods. This is particularly so in the case of a possible release of 131I. Suitable instruments for the former purpose are described in Annex VI; for the latter purpose, more exact techniques may be required The use of gamma-radiation surveys to predict i3ii levels in milk A release of1311, either alone or as one component of a mixture of radionuclides, to atmosphere in a dairy farming area will call for the rapid provision of information on which to base decisions re garding any restrictions on the consumption of locally produced milk. If the composition of m aterial deposited on to pasture land is known, measurement of gamma exposure-rate over the ground surface can be used to estim ate the quantity of 131I deposited per unit area of ground and hence to predict future levels of 131I in m ilk. It is necessary that gamma exposure-rate measuring instruments used for this purpose should be capable of detecting an increase in exposure-rate over the ground surface equivalent to that amount of 131I per unit area of ground which could lead to the emergency perm issible level in the milk of cows grazing the affected area. In the United Kingdom the emergency permissible peak activity of milk set by the Medical R esearch Council [16] is currently MCi/litre. From Table II. 6 of Annex II it can be deduced that the corresponding deposition is approximately 0.4 /uci/m2. (a) Surveys using simple portable instruments The exposure-rate at 1 m above a plane surface contaminated with 0. 4 MCi/m2 of 1S1I is 3. 3 AiR/h [13]. The natural background varies according to locality; in the United Kingdom it ranges typically from 6 to 15 jur/h. It is evident that the sensitivity range of any instrument must be better than 0 to 100 /jr/h and that, for any accurate 71

84 l -ENERSf (MevJ FIG. III. 1. Energy sensitivity of British ratemeters Type 1368A and Type 1413A [17] assessm ent of the contribution to the gamma exposure-rate from an accident, frequent background surveys are necessary. The sensitivity requirements are met by many of the beta/gamma monitoring instruments described in Annex VI. Instruments using scintillation counters are, in general, markedly energy-dependent, having a greater response per roentgen per hour for low- rather than high-energy gammas. The United Kingdom beta/gamma monitor Type 1413A and the Type 1597A which is replacing it, for example, have a factor of overestim ation for 131I gammas of 3.1 (Fig. III. 1). These instruments held at 1 m above a plane surface contaminated with 0.4 MCi/m2 of 131I, with no nuclide other than 13ll present, would thus read 10 nr/h. 72

85 In using portable instruments for environmental monitoring, the following procedures should be adopted: (i) M easurements should be made at a standard height (1 m) over short grass on undisturbed land (common grazing, heath, permanent pasture) to avoid changes which occur when vegetation contaminated by fall-out is either harvested or ploughed under, and at least 20 m from any building, barns, roads, drives, railways, bridges, or any heaps of m aterial such as gravel, rubble or road-grit. These all contain varying amounts of natural activity, mainly uranium or thorium products. Haystacks or silos should be avoided since they may have contained, in a concentrated form, the total fall-out deposited on grass which originally covered a large area. T rees and hedges also act as co l lectors of fall-out which is washed out to a variable extent by rain. In an emergency they may trap large amounts of air-borne particulate matter and give a high gamma-radiation reading which is not representative of the average value of that area. (ii) Precautions should be taken against contamination of the instrument. The best way of checking the datum level (cosmic background plus inherent count-rate of the instrument) is to read the instrument over a stretch of water. (iii) Representative samples of grass and soil, from measured areas of ground, should be taken at reference stations where repeated gamma-measurements are made. (iv) Comparisons should be made between the reading of scintillation instruments and the exposure-rate measured by an ionization chamber or GM-counter. The latter instruments are le ss energy-dependent than scintillation counters and the comparison will therefore give some indication of the nature of the deposited m aterial. (b) Surveys using car-b orn e instrum ents If an instrument is mounted in a car and its output is connected to a chart recorder, a rapid and continuous survey can be made and the results recorded for future referen ce. The disadvantages are that the vehicle may become contaminated and that the exposure-rate over the road will not be the same as over pasture. In addition, there are anomalies in the background gamma exposure-rate over roads 73

86 and near buildings, caused by the use of granite and similar materials. These difficulties can be reduced by mounting the instrument on a pole extending above or to one side of the vehicle, so that the detector receives a greater proportion of gam m a-rays from activity on the adjacent fields. FIG. III. 2. Landrover as used in the United Kingdom with ratemeter Type 1413A on pole [17] Figure III. 2 shows a Landrover vehicle with a ratemeter, Type 1413A, mounted on the top of a vertical 3. 3-m pole, as used by the United Kingdom Atomic Energy Authority. The output of the ra te meter is fed to a chart recorder while a push button operated by the driver actuates a marker working in the margin of the recorder chart. If the vehicle is driven round a predetermined route, the chart can 74

87 be marked as land-marks are passed and the position of the marks correlated with a large scale map at the end of the run. By driving at a steady speed, about 30 km/h, the charts can easily be compared one against another. It has been shown that, under favourable conditions, a deposition of 131I equivalent to about one tenth of the British Medical Research Council emergency perm issible level in milk can be detected using such a system [17]. (c) Surveys using fixed-wing aircraft An aerial survey is a rapid method of establishing the pattern of fall-out. Such surveys are usually carried out at a nominal height of 170 m. The true exposure-rate at this height is about one tenth of that at 1 m above the contaminated ground surface, this factor being approximately independent of the initial gamma-energy in the range MeV [13]. The count-rate at 170 m corresponding to 0.4M Ci/m 2 of i31i, with no other radionuclides present, is about 130 counts/s on both the British Type 1531 aerial survey instrument [13] (this uses three Nal(Tl) crystals, 12 cm diam., 2. 5 cm thick) and the American 53N equipment (see Annex VI). The total contribution from the instrument, cosm ic rays and natural activity in air (i.e. the reading over water) is approximately counts/s; this rem ains fairly constant with tim e and position. The contribution to the count-rate at 170 m from natural activity in the ground varies from about 250 counts/s over chalk to 670 over granite. This response is also dependent on the height of the aircraft. It follows that the count-rate due to 0.4 idci/m2 of 131I would be of the same order as the variation associated with different geological strata. If background surveys are made along known flight lines over the district around the nuclear facility, and the same flight lines are followed in any subsequent operational survey, it should be possible to detect the presence of 0.4 mci/m2 of 13il with reasonable accuracy. (d) Surveys using helicopters Helicopters have the advantage that the air speed is much lower and that measurements may be made clo ser to the ground surface. A less sensitive detector may therefore be used and standard portable gamma survey-meters coupled to chart recorders have performed satisfactorily. 75

88 The B ritish Type 1413A or 1597A ratem eter gives an increase in response equal to background for a level of 0.4 nci/m2 of 131I on the ground at 17 m and for a level of 1 /uci/m2 at 35 m [18]. Similar results have been obtained with survey equipment developed by the Centre d'etude de l'energie nucleaire, Mol [19]. Figure III. 3 shows the response of the latter instrument, used either for measuring total gam m a-radiation or as a single-channel spectrom eter channelled on the 131I peak (see below) at various altitudes over an area of 7000 m2 artificially contaminated at a level of 1 /^Ci/m2 of 131I. The response over a larg er, uniformly contaminated area would be expected to be about the same. (e) T h e u s e of a n c illa r y m e a s u r e m e n ts a n d / o r m o re re f in e d in s tr u m e n ta tio n The above considerations have referred to situations in which 131I alone is present on the ground surface; in practice other isotopes will usually be present. The possible variations in composition of deposited m aterial are infinite but four general situations can be re cognized for the purpose of comparison [13]: (i) Mixed fission-products released in a very short time from a criticality excursion in a previously zero energy system; th ese can be term ed "instantaneous fissio n-p ro d u cts"; (ii) Mixed fission-products in the proportions found in fuel after long irradiation (300 days may be taken as a standard period); (iii) Volatile fission-products (iodine, tellurium, caesium) in the proportions found in fuel irradiated for 300 days; (iv) 131I only (perhaps from a mishap in a chemical separation plant). Figure III. 4 shows that the exposure-rate at 1 m associated with a deposition of 0. 4 /^Ci/rn2 of 131I, measured at one day afterwards, may be anything between 400 and 3 nr/h depending on which type of release has occurred. Moreover a release could be intermediate in nature between two of the cases (i) to (iv). Although, given some knowledge of the nature of the m aterial released gamma readings obtained using simple instruments can be used for rapid delineation of areas in which milk consumption needs to be initially prohibited; it is evident that for a proper appreciation of the situation they must be interpreted by referen ce to m easurements of 131I and other nuclides in grass and milk. Suitable sampling and analytical methods are described in Annexes IV and V. 76

89 HEIGHT (m ) COUNTING-RATE (counts/s) FIG. III. 3. Measurements from helicopter above an area of 7000 m* contaminated to a level of 1 jici/m* with oil [ig j

90 sooo TIME SINCE RELEASE (d) FIG. III.4. True gamma exposure-rates from fission-products associated with 0.4 jici/m2 of 131I on the ground [13, 21] Alternatively instrum ents must be used which permit selective measurement of the 131I deposition. The most direct method of identification of many nuclides, including 131I, is by gam m a-spectrom etry. The introduction of transistorized equipment has allowed the development of both portable and transportable gamma-spectrometers. The simplest instruments make use of energy discrimination by providing pre-set channels in a simple gamma-monitor. The monitors can then be set up by skilled personnel for a specific purpose (e.g. channelled on the 364 kevpeak of 131I for m easurem ent of 131I on the ground or in milk) and subsequently used in the field by le ss skilled personnel. Completely portable radiation spectrom eters are also available. The use of selective instruments in a moving vehicle (with the detector mounted on a pole in a sim ilar fashion to the ratem eter shown in Fig. III. 2) and in a helicopter have recently been described [19, 20]. 78

91 TA BLE I I I. 2 RESPONSE OF INSTRUMENTS VERSUS CONCENTRATION IN W ATER Water concentration (jici/cm3) Instrument Reading 10 "3 "Cutie-pie ionization chamber instrument at 1 m 2 mr/h 10 "4 GM counter instrument at 1 m 400 counts/min 10 -s 53N scintillation detector instrument at 170 m 10 "6 53N scintillation detector instrument at 1 m 5 X 10 ' 6 53N scintillation detector instrument on bottom of boata 2 X N scintillation detector instrument (collimator off) on bottom of boat 8000 counts/min 8000 counts/min 8000 counts/min 8000 counts/min a Double-hulled, outboard motor boat W ater surveys Instrument surveys can be used to estim ate quickly the concentrations of fission-products and other beta-gamma emitters in rivers, lakes and oceans. Readings can be taken from a boat using portable survey-m eters or using aerial survey equipment provided the body of contaminated water is reasonably large compared to the effective size of the infinite plane source for the instrument in use. Table III. 2 indicates the approximate response of the instruments described in Annex VI versus concentration in water, based on Hanford experience and calculations. If a reservoir or river which is used as a water source is located within an area contaminated following an accident the contamination should be assessed by a water survey as soon as possible. Because of the large dilution in the sea it is extremely difficult to make direct measurements of the contamination and it is usually necessary to re sort to sampling techniques. 79

92 A N N E X IV S A M P L E C O L L E C T IO N AND F IE L D E V A L U A T IO N 1. A ir sa m p le s 1.1. Particulate materials Collection Particulate m aterials may be collected by fixed atmospheric monitoring equipment or portable equipment operated in the field during the passing of the cloud. Portable batteryoperated air sam plers having a capacity of 10 litres per minute (1/3 to 1/2 ft3 per minute) are often used for filter sam pling. F ilte r papers employed for a ir sampling include a s bestos fibre mat (CWS-6, H-70inUSA), fibreglass, and c e l lulose e s te r membrane paper (M illipore, Polypore). Any of these can be employed for a ir filte r sampling, although the high pressure drop of some membrane filte rs may p reclude operation at the high flow-rates required for rapid field detection of abnormally high air-borne concentrations during an emergency. The paper chosen should have been evaluated in the routine environmental surveillance programme to provide information on collection efficiency, and pressure-drop versus flow-rate ch aracteristics. Charcoal impregnated filter paper may be used where collection of radioiodine is desired. Pre-em ergency evaluation of the paper will determine its collection efficiency. Although different grades of paper having different collection efficiencies are available, a reasonable assumption in the absence of experim ental data would be 80% for radioiodine Field evaluation of beta-emitters The air concentrations leading to lung or critical organ doses comparable to the British Medical Research Council "lim its"1 are easily measurable in the field via survey-meter readings obtained on exposed air filte r papers. Using reasonable a s sumptions as to filter collection efficiency (80%) and GM 1 See Annex II, T ab le II

93 s u r v e y -m e te r counting efficien cy (2 %), one can d erive T able IV. 1 of detection lim its v e rsu s operating tim e fo r a 1 0 litre per minute sam pler. TABLE IV. 1 M E T E R READINGS ON A IR F IL T E R S A M P L E S VERSUS A IR C O N C E N T R A T IO N S O F B E T A -E M IT T E R S A ir concentration ((jc i/ cm 3 ) O perating tim e at 10 litres/m in GM m eter reading at surface o f filter (counts/m in) 10 ' 6 1 min ' 7 5 m in ' 8 30 min ' 9 4 h 100 It is possible to define the tim e-integrated air exposure during cloud passage and predict the resulting ground contamination from su rv e y -m e te r readings on filte rs rem oved fro m fixed atm ospheric monitoring stations after the cloud has passed. The same assumptions as to collection efficiency and instrument efficiency apply as for the portable air sampler calculations. In addition it must be assum ed that a ll m easured radioactivity cam e fro m the accident. (1) M C i/filter = R /( ) = R '/(5 0 ) where R = background corrected (net) cou n ts/m in obtained on a portable G M s u r v e y -m e te r with beta sh ield open (W. O. ) held at su rfa ce of filte r paper, R 1 = ionization ch am b er (cutie pie (CP) or Juno type with ~ 7 m g /c m 2 window) surface reading in m rads/h. (2) E= (juci/filter)/(sample flow in cm 3 /s ) where E = time integrated air exposure in units of M Ci-sec/cm 3 or C i-se c /m 3,- 81

94 (3) C = E/T where T = total time of cloud passage in seconds, C = average air concentration at sam pler during cloud passage in f.ic i/cm 3* (4) D = EXVg XlO6 where D = ground deposition in units of ^ C i/m 2, Vg = average deposition velocity for particulates in m /s. (At Hanford a suitable average Vg is taken to be 5 XlO ' 4 m /s ) Field evaluation of alpha-emitters The sam e considerations apply to a lp h a -em itters collected on a filte r paper sam ple a s apply to b e ta -e m itte r s. The principal difference is the type and efficiency of the survey instrument used to m easure the collected m aterial. Either an air proportional ionization chamber or a ZnS scintillation probe may be employed in a portable battery-operated survey- meter. The sensitive window of these instruments is normally about cm 2. The background of the instrument is nearly zero and the minimum detectable quantity of an alp h a-em itter is about 2. 3 X lo ' 4 /uci per probe area. The instrument read-out is through "p o p p in g " sounds in a headphone set and thus the m easu rem ents are only qualitative. D ifferent strength sources can be carried into the field to use for com parison with the m easured activity to quantitize m easurem ent. Table IV. 2. su m m a rizes the detection lim its fo r alphaem itters in air when sam pling at 1 0 litr e s per minute. Exposure predictions can be made as follow s: (1) M C i/filter = m eter reading in ju C ix r where r = a correction for filter paper size, r = 1 (if the area of the filter is the probe area), filter area r = (if filter area > probe area), probe area r ' 82

95 TA BLE IV. 2 M ETER READINGS ON AIR F IL T E R SAM PLES VERSUS AIR CONCENTRATIONS OF A LPH A -EM ITTERS A ir co n cen tration (/ici/cm 3) Operating tim e at 10 litres/ min Portable poppy m eter reading 0*C i) 10 ~8 2 m in 2. 3 X 1 0 '4 1 0 ' 9 22 m in 2.3 X 1 0 " * h 2.3 X 1 0 " h '2.3 X 1 0 "4 (2) the tim e-integral of concentration in air (E), the average air-concentration at the sam p ler during the passage of the cloud (C), and the ground deposition (D) may be derived fro m /u C i/filter according to the procedure d e scrib ed in section fo r b e ta -e m itte r s Radioiodine Collection and field evaluation Field estim ates of radioiodine concentrations may be obtained in the same way that other beta-em itters are estimated provided that the collection efficiency of the paper for iodine is known, or the radioiodine is present in an estim atable ratio to other particulate m aterials efficiently collected on the filte r. If charcoal-im pregnated filter paper is used for sa m pling, then iodine may be assum ed to be collected with about 80% efficien cy. Sm all ch a rco a l-fille d ca rtrid g es m ay also be used for radioiodine collection and field estim ations can be made using portable GM or scintillation instru m en ts, provided p re-em erg en cy calibration fa cto rs have been d e rived. The calculation of air-concentrations, integrated ex posure and ground deposition follow the steps outlined above. The one exception is the use of a deposition velocity (Vg ) for halogens (norm ally taken to be about 5 X IO " 3 at Hanford) in place of that for particulates. 83

96 1,2.2, Collection of samples for laboratory analysis Accurate spot field sam ples are best collected by operating a sm a ll caustic scrubber with the 1 0 litres per minute p ortable air pump. A sm all plastic test tube holding 50 cm3 of 0. I N NaOH is sufficient to determine l31i concentrations as low as 10 9 juci/cm 3 in a 5-minute sample, provided laboratory analysis by ch em ical separation and beta-counting is employed. The resulting laboratory analysis yields a sample which should count about 2 0 counts/m in above a 2 0 counts/min background on a thin m ica-w indow GM counter having 20% geom etry. 2. Water sam ples N orm ally the procedures d escrib ed in Annex III fo r w ater su rvey w ill be su fficien tly sen sitive to supply inform ation upon which decisions to restrict the use of the water can be based. If a lp h a -em itters without accom panying g am m a - em ission are present then m easurem ents of water concentrations must be made by collecting sam ples for evaporation and measurement of the residue in the field or in the laboratory Field evaluation Concentration of radionuclides in water samples can be m easured in the field by im m ersin g the probe of a beta-gam m a survey instrument in the centre of the sample container. Care should be taken to secu rely wrap the probe in a thin w aterproof covering to protect it against water damage and con tamination. Various types of probes can be used both inside and outside the w ater container. Table IV. 3 su m m arizes the approxim ate readings obtainable with a portable GM survey-m eter probe im m ersed in solutions of certain nuclides Collection of samples for laboratory analysis Gross measurements Pre-accident plans should be available to define the probable nuclide(s) present so that rapid gross activity m easurements 84

97 TA BLE I V. 3 [ 2 2 ] GM SU R V EY-M ETER OPEN WINDOW READINGS (counts/min per juci/litre) (Probe im m ersed in contam inated w ater) S iz e o f sam ple contain er N uclide 1 litre 5 litres 10 litres 89Sr Sr + 9 Y Ru Rh j Cs B a + 14 La are sufficient to determ ine the n ecessity for restrictio n of water u se. Detailed isotopic analysis can be deferred until m ore tim e is a vailable. F o r g r o s s alpha- or g r o s s b eta - analysis 5 0 -c m 3 samples are sufficient. Larger sample containers can be used if necessary, but since the sam ples must be evaporated before counting, valuable tim e w ill be saved by instructing the laboratory to use the sm a lle st p ractical sam p le volu m e. The estim ated cou n tin g-rates obtainable fro m various w ater contamination le v e ls are illu strated in T able IV. 4. Certain nuclides m ay yield rates much below those listed, especially if their radiations are of low energy or if the particle being counted is emitted in only a sm a ll fraction of the d isin tegration s. Counting e ffic ie n c ie s fo r the nuclides of concern should be established before the accident. Consideration should be given to bulking water sam p les collected over large areas prior to analysis in order to reduce the laboratory work load. A n a ly sis of individual sam p les can be delayed until m ore tim e is available or until a significantly high concentration has been found in a bulked sam ple. 85

98 T A B L E IV. 4 TYPICA L COUNTING-RATES ON LABORATORY INSTRUM ENTS VERSUS W ATER CONTAMINATION L E V E L S Radiation emitted Water concentration (MCi/cm3) Sample size (cm3) Conting-rate (net) (counts/min) Beta 10 "«50 20a a 10 *4 1 40a 10 " a Alpha 10 " b 10' b b a On a thin-window beta-counter with 20% counting efficiency. b On a ZnS scintillation counter with 40% counting efficiency. 3. M ilk sa m p le s 3.1. Field evaluation of 131I using portable survey-meters Portable su rvey-m eters of various types can also be used to estimate concentrations of 131I in milk at or above the British M ed ical R e se a rch Council " l i m i t " of /uci 131I /l i t r e. Readings can be taken inside a 4 0 -litre milk can if the meter is wrapped in waterproof plastic, A faster, le ss sensitive, method is to take readings outside the milk can at the surface of the m etal w all. A sum m ary of typical readings obtained with three different portable su rv e y -m e te rs and with the transportable scintillation equipment is given in Table IV Field evaluation of 131I using transportable scintillation gamma-energy analyser Milk concentrations corresponding to about one-tenth of the British Medical Research Council "lim it" of /uCi 133 /litr e 86

99 TA BLE I V. 5 [ 2 3, 2 4 ] SU R V EY-M ETER READINGS VERSUS CONCENTRATION OF 131I IN A 4 0 -litr e MILK CAN Meter used (jc i131 I/litre milk Inside can Net counts/min Outside can Al-walled GM probe Background Mica-window GM probe Background a, fl, f scintillation survey-meter Background Transportable single-channel analyser system Background 30 - a Crystal is 3-mm thick disc of "Bioplastic" scintillator sprayed with 10 mg/cm2 of ZnS. Effective area is 6.4 cm 2. 87

100 are detectable in the field with a transportable single-channel analyser system. Field determinations should be practicable for several hundred 40-litre milk cans per day using this type of equipm ent. A N al scin tillation c r y s ta l of about 4 cm diameter by 2. 5 cm height is the preferred detector, although larger crystals may be used. If the single-channel analyser is operated with a M e V window then the counting-rate obtained at a setting of M ev is about 80 cou n ts/m in above a 30 counts/m in background when the crystal is inserted in a 40-litre can of milk containing juci 131l/litr e Field evaluation of radionuclides other than 1311 Nuclides, other than 131I, of possible interest in milk are 89Sr, 9 0Sr, 137Cs and 149Ba. Usually these will be associated with 131I which should be the limiting nuclide. In instances where 131I is not present, monitoring for these others may be necessary. The field evaluation techniques described for l3ii are applicable to these other nuclides. The same counting-rates perjuci/litre should be obtained on a GM meter for these nuclides in m ilk as in water (see Table IV. 3). The B ritish M edical Research Council "lim it" for 90Sr in milk (2. 2 X 1 0 ' 3 (uci/litre) is only about 3% of that for isil (6.5 X 10 ~2 ^ C i/litre) and the 9t>Sr' w ill therefore be undetectable in the intact field sam ples at this level. The "lim it s " for 90Sr, i37cs and 140B a+ 140La are sufficiently high to make field evaluation with a G M m e te r practical. The i37cs and 140Ba can also be measured at their respective gam m a-energies with the transportable equipment. 4. Sampling of cereals, fruits and vegetables In certain countries of the E astern H em isphere as much as 50% of the dietary calcium may be derived from cereal grains, while fru its and vegetables m ay add another 25%. In such countries field evaluation on vegetation samples might provide u sefu l inform ation on the need for crop confiscation or d i version from human consumption. No special techniques are required for the sampling of ce re als, fruits and vegetables. Before analysis, however, they should be treated in the same way as if being prepared for human consumption. Sam ples co llected fo r a n a lysis should weigh approxim ately 500 g. 88

101 5. Vegetation sam pling Sampling of the herbage eaten by grazing animals allows prediction of the subsequent levels of radionuclides in their milk Collection The vegetation cover from at least 1 m2 of ground should be collected the aim should be to obtain at least half a kilog ra m m e. The vegetation should be cut at the appropriate height ( 1-2 cm ) in ord er to obtain an estim ate of what a grazing animal would consume by simulating its grazing behaviour. Care must be taken to prevent the cut material from being contaminated with soil. It must be recognized that sam ples of vegetation cut in this way w ill not represent exactly what the grazing animal consumes particularly when the pasture is very varied in composition. Vegetation sam ples can, th erefore, give only a rough indication of the intake of the anim al Field evaluation [22, 25] A method of estim ating vegetation contam ination le v e ls is described in the follow ing stepw ise procedure: (a) Cut enough vegetation as described above to fill a 3 0 c m X 4 0 c m p la s tic bagabouthalf full. This represents about one-half of a kilogram m e. (b) C om press the air out of the bag and seal the end. (c) Move to a low background area. (d) Flatten the plastic bag and lay the probe of a portable GM su r v e y -m e te r on the centre of the bag. (e) Fold the bag over the GM probe and note the reading (window open and background corrected ). ( f ) Calculate the vegetation contamination le v e l fro m the following equation: C = R /k where C = vegetation concentration in /uc i/kg, R = GM m eter reading in units of 102 Xcounts/m in (background corrected), k = 102 Xcounts/m in per /uci/kg as given in Table IV

102 TA BLE IV. 6 TYPIC A L GM SU R V EY-M ETER READINGS PRO BE INSERTED IN THE CENTRE OF A LARGE SAM PLE OF VEGETATION Nuclide (102 x counts/min per (jci/kg) k 89Sr, *9Sr + 90Y Ru+ I06Rh 50 i40ba+ no La 10 1SII, 137 Cs 4 6. Marine products The monitoring of marine products is not dealt with here in detail since it form s the subject of a separate IAEA publication2. 2 INTERNATIONAL ATOMIC ENERGY AGENCY, Methods of Surveying and Monitoring Marine Radioactivity, Safety Series No. 11,IAEA, Vienna (1965) 95 pp. 90

103 A N N E X V S P E C IA L A N A L Y T IC A L C O N SID E R A T IO N S 1. Speed v e r s u s s e n s itiv ity In the first few days following an accident, where information is required with as little delay as p o ssib le, rapid and r e latively simple, albeit crude, analytical methods may be preferred in order that the analytical facilities available should not be overloaded. A s an example of the loss in sensitivity to be expected if rapid answ ers are required, the analysis of water may be considered. The detection level of counting methods used at Hanford fo r variou s radionuclides are listed along with the method used in Table V. 1. If a quick approximate answer is desired, the detection level will be about tim es higher than those listed. An estim ate of the number of hours required to get such em ergency answ ers is also included. 2. Techniques In m ost ca ses the radionuclides of im portance w ill prove to be 1 3 1I, is^cs, 89Sr and 90Sr, 13 1I, l37c s (and many other fission -p rod u cts) are capable of rapid determ ination, after suitable treatm ent of the sam ple, if n ecessary, by gam m a- spectrom etry. Radiochem ical analysis will, however, be r e quired for the strontium isotopes. An example fast method, adequate for use in the ea rly stages of an em ergency, and applicable to a number of m aterials, is described below. Full information on routine methods of analysis is given in a number of publications [27, 2 8 ] Ashing of samples Conventional dry-ashing techniques can be used for most m a te r ia ls. Methods applicable to biological sam ples are d e scribed in detail elsew h ere1. Milk presents a special problem. A suitable procedure is as follow s. 1 See: Food and Agriculture Organization. "Report on the Organization of Surveys for Radionuclides in Food and Agriculture" Annex C (1961). 91

104 TABLE V.I [2 6 ] D ETECTIO N L E V E L FOR VARIOUS RADIONUCLIDES IN W ATER SAM PLES Radionuclide Counting method Detection level ((jci/ml) Tim e required for emergency answers (h)?sas Beta proportional counter 1.5 x lo ' j Beta proportional counter and decay 1.5 x 1 0 ' Sc Gamma-gamma coincidence counts 2.4X 10'* 2.0 **Na Gamma-spectrometry 1. 5 x 10 " Zn Gamma-spectrometry (assumes no interference Np Gamma-spectrometry (assumes no interference) 6.5 X 1 0 '* 4.0 X 1 0 '* 2.0 cu Gamma-gamma coincidence counts 8.0X 10'* 1.5 7*Ga Gamma-spectrometry 1.4X 10'' SICI Th (n at.) Gamma-spectrometry (assumes no interference) Gam ma-scintillation with 234 Th reference standard and neutron activation 1.1 X 1 0 ' X 1 0 '9 90Sr+ 90Y Low background beta proportional counter *9S r + 9"Sr Low background beta proportional counter 2.0 X 1 0 ' XlO ' p Beta proportional counter 6.4X 10" ' Ca Beta proportional counter 1. 8 x 10"* RE + Y Beta proportional counter and decay 5.6 x 1 0 "* Fe. Beta proportional counter and gamma-spectrometry 91 Si Beta proportional counter and decay 1.5 X 10' X 1 0 '7 Mn Gamma - spectrometry 5.8X 10'? 1.0 " B a Beta proportional counter and decay (checked by gamma-spectrometry) 5.7 X10' m l m ilk are shaken with S r-ca rrie r (50 mg Sr) and after that transferred into a separatory funnel placed over a 1 -litre beaker containing 300 m l boiling concentrated HNO3. The m ilk is added dropwise to the boiling acid in approxim ately 1 hour (1-2 drops per second) under constant stirring. The 92

105 boiling and stirrin g are continued a fter a ll m ilk has been added until the solution begins to sp atter. The solution is then quantitatively transferred into a silica tray and the evaporation is com p leted under an in fr a -r e d lam p. The black residue in the tray is ashed over a bunsen burner until the ash is g re y. 3 hours Radiochemical separations [29] The total ashing p ro cess w ill last approxim ately Rapid assessment of 89Sr and 90Sr (a) Procedures (i) The ashed sample (approximately 1 g ash) is treated with 15 m l w ater and approxim ately 5 m l HNO 3; the insoluble residue (carbon) is removed by filtration and the clear solution is collected in a m l beaker. The solution is evaporated to 15 m l and tra n sfe rre d to a centrifuge tube m l (ii) 30 m l fuming HNO3 is added under stirring and cooling. The stirring and cooling are continued for 15 m inutes. (iii) The sample is centrifuged and the super-natant liquid is discarded. The residue is dissolved in 10 m l water, and 22 m l fuming nitric acid is added. Stir and co o l for 15 m inutes. (iv) Centrifuge and b le e d -o ff the super-natant liquid. (v) The Sr(NC>3 )2 -precipitate is dissolved in a few drops of water. 1 m l Y -c a r r ie r (10 mg Y /m l), and 2 m l 6 N am m onia water are added under stirrin g in a w ater bath. Cool and centrifuge. The precipitate is discarded. The analysis after this step has to be completed and the sam ple counted within 4-5 hours (otherwise 90Y w ill disturb the counting and yield an over-estim ate of 8 9 Sr). (vi) 1 drop m ethyl red solution is added and the solution is neutralized with 6 N HNO 3. 1 m l 6 N CH 3COOH and 2 m l 6 N C H 3 COONH 4 is added (ph = 5. 5). T h is is heated n early to boiling then 2 m l B a -c a r r ie r (10 m g B a /m l) and 1 m l N a 2 CrC>4 are added dropw ise under stirrin g. The BaCrC >4 is rem oved by centrifugation. If 140Ba is believed to be present in large quantity repeat this step (vi). If no 140Ba is p resen t this step can be om itted. 93

106 (vii)a dd a drop of 30% H 2 O 2 to the super-natant liquid and 2 m l ammonia water (ph= 10). Heat to boiling until all H 2 C>2 is destroyed and add during boiling and stirrin g 6 m l saturated (COO)2 (NH.j)2 solution dropw ise, cool and filter the strontium -oxalate through a tarred filter. D ry at 110 C for 1 /2 hour. Cool, weigh as (COO) 2 Sr H2 O and mount the sam ple. Count with, and later without, 1 m m A l-a b so rb e r. (b) Calculations Activity of 89Sr - Tgg XHggt x X U X E 89 pcl C QQ activity of 9 Sr = e ^ o Tx! ^ pci where C in cou n ts/m in is the counting-rate for the strontium oxalate sam ple without the A l-a b so rb e r, Ca in cou n ts/m in is the counting-rate for the strontium oxalate sample with the A l-ab so rb er, T 89 is the fractional transm ission of the radiation from 89Sr through the absorb e r2, U is the fractional yield of the strontium oxalate, Egg is the co u n tin g-efficien cy fo r 89Sr in the sa m p le, Ego is the countirfjg-efficiency fo r 90Sr in the sa m p le, Hggt is the fractional decay of 89Sr for the time t in days which has elapsed between sampling and counting. Note: (1) T 8g, Egg and E 90 are determined by counting pure sa m ples of 89Sr and 90Sr. (2) The 1 m m A l absorbs effectively a ll the beta-radiation from 90Sr. _ counting-rate with absorber present 89 counting-rate without absorber 94

107 2.2,2, Rapid assessment of 131I and/or 90Sr in water [30] The iodine can either be distilled o r extracted into carbon tetrach lorid e and the strontium can be precipitated as the carbonate. (a) (b) (c) Iodine is distilled into ic e -c o ld carbon tetrach lorid e fro m an acid solution to which sodium nitrate has been added. An aliquot of the carbon tetrachloride solution is then counted in a w e ll-c r y sta l. R esults can be r e ported in le s s than 1 hour. Iodine can be extracted from up to 500 m l of acid-nitrate solution into m l of carbon tetrachloride. The extracted iodine is reduced with bisulphite and back ex tracted into approxim ately 500 m l of w ater which can then be counted in a large w e ll-cry sta l. Results can be reported within 11/4 hours. The strontium content of the carbonate precipitate can be estimated' by beta-counting. If the precipitate from about 50 m l of the sam ple is counted and it is assum ed that a ll the activity corresponds to 9 0Sr, resu lts can be reported within 1 hour, but the 90Sr content will be overestimated Rapid assessment of 131I and J37Cs in milk [29] (a) 131I The m ost rapid method to determine 131I in a m ilk sample is the direct gam m a-m easurem ent of the sample on a scintillation cry stal in conjunction with a pulse-height analyser. If however it is desirable to obtain a greater accuracy it is advisable to separate the iodine from other activities, e.g. 140Ba and i3 7G s. The milk could then be treated as follows: 1 mg Nal carrier is added to 100 m l m ilk and thoroughly stirred in. The m ilk is centrifuged and the cream removed. The sk im m ed m ilk is fo r about 1 hour p a ssed through an approxim ately 3-cm high colum n co n sistin g of 5 m l wet settled D ow ex 1 X 2 (2 0 0 /4 0 0 m esh) r e sin. 95

108 The resin is transferred to a measuring cylinder, which fits into a sodium iodide w ell-crystal in conjunction with a pulseheight analyser and is measured for 131I. (b) 137 Cs 137Cs (y: MeV) is most conveniently determined by gamma-spectroscopy directly on the milk. If, however, 132I (y: 0.67 MeV), the daughter product of 77 h I32xe, is present in the milk in larger quantities, it is necessary to measure 137Cs on the anion-exchanged milk obtained from the 131I procedure described in (a) above.

109 A N N E X V I IN S T R U M E N T A T IO N AND E Q U IP M E N T 1, In stru m e n ts and equipm ent in com m on use in the United Kingdom 1.1. Equipment carried by a typical vehicle intended for emergency environmental monitoring 1 12-volt battery 1 12-voltdust-sampling pump1 2 Compressed air samplers 1 Portable dual-phosphor air-sample probe2 1 Portable contamination monitor Type 1320 with alpha and beta probes, alpha and beta castles and reg ister unit 1 Type 1368 field gam m a-ratem eter 1 Type 1413 field gam m a-ratem eter3 1 Type 1349 beta-gamma d ose-rate monitor 6 Q uartz-fibre electroscopes, range R 1 Charging unit for quartz-fibre electroscopes 2 Lamps 2 Hand torches 6 sets Protective clothing 1.2. Dust sampling unit, Type 1651 A. The unit is designed to collect air-borne dust from a known volume of air. The alphaor beta-activity is then measured with an alpha-scintillation counter or beta end-window counter. A dual-phosphor probe for this purpose is com m ercially available. The air-borne dust is drawn by a positive displacem ent pump driven by a 12-V DC electric motor through a standard filter paper set in a detachable supporting fram e. The throughput is m easured internally by means of an anemometer, the time being measured by m eans of a stop watch. The sampling rate is 1 Similar to Type 1651A described in section EMI Type PCM 1 monitor with a Type DP2 alpha-beta probe. This is a commercial instrument. 3 The Type 1413 is now being replaced by the similar Type 1597A described in section

110 50 litres/min. The unit has an estimated service life of three years when operated for a period of 8 hours a day. (Self-powered sets driven by sm all co m p ressed -air containers are also in use, e.g. Type W. A. S. 1). Alpha, beta/gamma radiation monitor, Type A portable, battery-operated instrument used for the detection and m easurem ent of alpha-, beta- and gam m a-contam ination. Two probes are included, a 1320 alpha-probe and a 1257 beta/gamma probe. The instrum ent covers three ranges of count-rate: 0-10 counts/s counts/s counts/s Headphones plug into a socket for aural indication of countrate. Total weight (including probes, haversack and headphones) 9 kg. Weight of instrument only 6 kg. Power is derived from six Mallory cells the battery life being approximately 60 hours. Beta/gamma monitor, Type A portable, batteryoperated instrument, primarily designed for geological survey purposes but now adopted as a health physics instrument for environm ental survey. A robust, sealed design. The in strument m easures gamma exposure-rate over five ranges: mr/h mr/h 0-1 mr/h 0-5 mr/h 0-25 mr/h A separate probe is available for the measurement of betaactivity. Headphones are available for aural indication of count-rate. Total weight, with accessories, 13 kg. Weight of instrument alone 4^ kg.

111 The energy dependence is enhanced at low gam m a-energies, i.e. by a factor of 2 at 0.15 MeV. The response time varies from 0.2 s to 25 s depending on the range in use and the m eter time constant chosen. This is a GM counter instrument with a fully transistorized circu it. The first four ranges operate with three GM counte rs Type CV 2147, the fifth range uses an MG 10H counter. The batteries have a useful life of approximately 500 hours Gamma monitor, Type 1597A. A portable, battery-operated instrument intended to replace the more fam iliar Type 1413, this monitor covers three ranges of exposure-rate measurement: 0-30/uR/h z^r/h nr/h The instrument was prim arily designed for geological survey work but has been adopted as a health physics instrument for environm ental survey. The ratem eter is fully sealed and desiccated and can be used under water to a depth of 1. 5 m. A socket is available for headphones for aural indication of cou nt-rate. Weight, 2 kg. The energy dependence is enhanced at low gam m a-energies, e.g. at 0. 6 MeV the reading is approximately 1. 5 tim es the actual exp osu re-rate, at MeV the reading is approxim ately 15 tim es the actual exp o su re-rate. The response tim e depends on the range in use with a maximum of 2. 0 s on the m ost sensitive range. The detecting element is a sodium iodide cry stal and photom ultiplier tube. The circu its are entirely tran sisto rized. The batteries have a useful life of approximately 500 hours. 99

112 1.6. Beta/gamma survey-m eter, Type A portable, batteryoperated instrument covering three ranges of exposure-rate measurement: 0-15 mr/h mr/h R/h A fully sealed, robust instrument. Weight, 3 kg. The energy dependence of the instrument is within ±20% for energies above 65 kev. The response time is approximately 6 s on the most sensitive range and le ss than 1 s on other ran ges. The instrument uses a parallel plate ionization cham ber of total volume 380 cm 3. The battery life varies from approximately 120 hours (low tension supply) to several months (high tension supply). 2. Instrum entation in common use at the Hanford Project, USA 2.1. Detection type survey-meters GM survey-meters The GM survey-meter is a portable battery-operated Geiger- Miiller instrument used for the detection of low intensity betaand gamma-radiations. Nearly all GM m eters are basically the same in construction and operation, although different - style probes may be connected through a one-m etre cable to the m eter. The most common probe in use at Hanford is the thin aluminium-walled (Thyac 1-B85) GM tube. Another probe used for measuring very low energy beta-radiation is a thin mica-window GM tube. Each instrument has three ranges: X I, XlO and X100; full scale m eter readings are either 800 counts/min or 1000 counts/min. GM su rvey-m eters are calibrated at Hanford to yield readings of 650 counts/min, 6500 counts/min and counts/min in fields of 0. 2 mr/h, 2 mr/h and 100

113 20 mr/h, respectively of radium gamma-radiation. Allowable erro r is ± 15% Scintillation Portable Poppy (SPP) The scintillation portable poppy (SPP) is a portable batteryoperated scintillation instrum ent developed at Hanford for the detection and qualitative measurement of sm all amounts of alpha-em itter s. The detector has an alpha-particle sensitive ZnS coating painted on a p lastic light pipe. The in strum ent "read -ou t" is through headphones which em it a popping sound for each count m easured. Instrument range is 500 dis/min to dis/min. Calibration is accom plished at Hanford with distributed sources of plutonium and a geometry of not le ss than 5% is required. Background is adjusted by a bias control to be S4 counts/min. Care must be exercised during use not to puncture the thin light-proof covering over the ZnS Alpha, beta, gamma survey-meter The a, /3, y survey-m eter is a Hanford prototype portable battery-operated scintillation instrument. The detector is a 3-m m disc of "B io p la stic" scin tillator coated with a 10 m g/cm 2 lay er of ZnS. The effective d etector a rea is 6.4 cm 2. The "Bioplastic" is coupled to an RCA 6199 phototube through a plastic light pipe. The meter has three ranges 103, 104 and 105 counts/min. It is described here principally because of its increased sensitivity over a GM surveym eter fo r field m onitoring of m I con cen tration s in m ilk Ionization chamber instruments Cutie Pie (CP) The CP meter is a portable, battery-operated, air ionization chamber instrument used to detect and m easure betaand gamma-radiations. The instrument measures radiation exposure-rates on three ranges of 0-50 mr/h, mr/h 101

114 and mr/h, The beta to gamma response ratio is about 1:4. That is, one dial division on the Or50 mr/h scale is 1 mr/h if the radiation is gamma only, and one dial division is about 4 mrad/h if the radiation is beta only. The ionization cham ber of the CP is 7. 6 cm diam eter by 14.4 cm long and has a volume of660cm3. The end window of the cham ber is 6 m g / c m 2 cellophane and the walls are 440 mg/cm2 phenolic. A removable 440 mg/cm2 phenolic beta shield is attached to the end window to aid in determining the proportions of beta- and gam m a-radiations present in m ixed field s. The CP m eter is calibrated for gamma response with a ra dium source to within -5%, +10% of the true exposure-rate. Spot checks are made with a natural uranium source to confirm the beta response Juno The Juno meter is a portable, battery-operated, air ionization chamber instrument used to detect and measure alpha-, beta- and gam m a-radiations. The instrum ent is basically the same as the CP m eter except for the chamber shape and its ability to measure alpha-particles. Chamber dimensions are 4. 4 cm deep by cm wide by 8. 3 cm long. It has a total volume of 440 cm 3. The aluminium chamber walls are 700 mg/cm2 thick. The flat bottom of the instrument has a window made of rubber hydrochloride only 0.7 mg/cm2 thick which will admit alpha particles to the chamber. This window can be covered by a beta window (alpha shield) of 6 mg/cm2 and a gamma window (beta shield) of 700 mg/cm2. The gamma calibration of the Juno is accomplished the same way as for the CP m eter. Beta calibration is performed with a slab of natural uranium and a beta d ose-rate versus dial reading calibration curve is placed on the side of the m eter. Alpha calibration is performed with a plutonium source, and a graph of disintegrations per minute versus dial reading is also attached to the m eter. The average alpha sensitivity of the Juno is about 5X 106 dis/min full-scale on the X100 range. 102

115 2.3. Aerial survey equipment A erial survey equipment normally employs one or more scintillation crystal detectors coupled to suitable phototubes, amp lifiers, count-rate m eters and recording ch arts. Most in strum ents use tran sisto rized circu itry to save weight and space. Some employ automatic altitude recording devices and even automatic altitude correction circu its in the countrate m eter. At Hanford a single scintillation cry stal is em ployed and no altitude recorder or automatic altitude co rre c tion is used. An early model of aeria l survey equipment (55B) employed a "B io p la stic" cry stal, 13 c m X l3 cm in size. This equipment is now maintained for riv er survey work from a 19-ft outboard boat. The present aerial survey equipment employs two interchangeable N alcrystals, one is 13 cm diam. X 7.6cm high (53N), the other le ss sensitive one is 5cm X 5cm (22N)4. The calibration of the most sensitive 53N equipment for the three ranges of 104, 105 and 106 counts/min is 2, 30 and 400 MR/h of radium gamma resp ectively. One /uci of 131I per square meter of ground will read about 8000 counts/min at a 170-m altitude on this equipment. The calibration of the 22N detector connected to the 53N electronic equipment is 27, 350 and 4500 nr per hour of radium gamma for the three m eter ranges of 104, 105 and 106 counts/min resp ectiv ely. The calibratio n for the 55B detecto r and associated equipment is 22, 110 and 1000 nr/h of radium gamma for the three ranges of 104, 105 and 106 counts/min resp ectiv ely. A ll three detectors are surrounded by a lead collim ator to lim it the response cone (50%) angle to 120 degrees which amounts to a viewed source diam eter of 600 m at 170-m altitude. The a ircra ft used for a e ria l survey at Hanford is a twinengine Beechcraft D185 owned and operated by the local office of the Atomic Energy Com m ission. Available on contract is a four-place Cessna a ircra ft also piloted by AEC per- 4 S e e F ig. V I

116 FIG. VI, 1. A erial survey instruments including three sizes of scintillation crystals, transistorized ratemeters and battery-operated chart recorders (Hanford Project - USA) Crystal sizes: 55-B cm x cm - Bioplastic 5 3-N cffix 7. 6 c m - N a I 22-N 5. l c m x 5. 1 c m - N a I sonnel. Background surveys are flown frequently over the project environs to assimilate information on normal readings. E stablished flight patterns and a e ria l check points are mapped in detail for reference during routine and emergency surveys Wind-speed meter Each Em ergency Environm ental Monitoring Kit includes a wind m eter (F.W. Dwyer Manufacturing Company). This m eter is a sm all hand-held, pitot-tube device calibrated in m iles per hour. It has two ranges of 2 to 10 mile/h and 2 to 65 mile/h. The m eter may provide useful wind speed inform ation in locations rem ote from fixed m eteorological station s. 3. M o b ile a ir m o n ito rin g u n it C e n tre d 'e tu d e s n u c le a ir e s de S a cla y, C o m m is s a r ia t a l'e n e r g ie a to m iq u e, F r a n c e [31] The unit consists of a Legueu a Meaux, type TF 4 10F, truck which can carry two passengers in addition to the driver, as well as the necessary instruments. The air pressure inside

117 the truck is maintained at a level slightly above the norm al atmospheric value and can be heated or cooled for the benefit of the passengers and equipment. A ir is drawn in through a filte r by a pump capable of delivering 60 m 3 p er hour. The electric supply is provided by a Leroy, type MDA 150, alternator, suspended in such a way that vibrations are not transm itted to the m easuring instrum ents. An em ergency supply is provided to perm it m easurem ents of beta- and gam m a-radiation to be continued, and rad io-contact to be maintained with the control cen tre. Aerosols may be sampled by drawing air through a MECI M4 filte r paper using a Lecomble and Schmitt pump capable of passing 15 m3 per hour. The air can also be passed through a specific absorbent cartridge for trapping radioactive gases. Gamma-radiation levels are measured using two Radiotechnique, type and 18552, GM counters, covering a range of 10 jur/h to 50 R/h. Beta-radiation levels are assessed by subtracting the readings given by a detector sensitive to gamma-radiation only from the readings given by a probe sensitive to both beta- and gamma - radiation. A Radiotechnique, type 18546, GM counter placed above the filter paper during collection of air samples provides a m easurement of the instantaneous gross beta-activity of the deposited aerosols. F o r measurement of the alpha- and beta-activity of the deposited aero sols the filte r paper is placed between a Radiotechnique alpha-scintillation detector and a Radiotechnique, type 18546, GM counter. The gamma-ray activity of the samples collected (either aerosols deposited on filter papers or gases trapped in charcoal cartridges) may be assessed using a gamma scintillation detector, MESCOLEP/T, coupled to a MESCO ECS T8 tran sistorized analyser. Arrangements are available for determining the energy spectrum of the radiation and for determining the variation of activity within an energy band. 105

118 The levels of external beta- and gam m a-radiation and the readings of the gam m a-spectrom eter can be recorded on a Compagnie des Compteurs, type E P R 3, ch art re c o rd e r. The truck is equipped with a Chauvin Arnoux, type televent, wind-speed and direction indicator. A Telecom m unications Radioelectriques et Telephoniques, type 313/20, transm itter-receiver is used for communication with the control centre and with other light vehicles. The unit operates on the frequencies allotted to the Commissariat k l'energie atomique. 4. Compensated ionization cham ber5 - Ristf Research Establishment, Atomic Energy Commission, Denmark [29] The instrument is designed for food monitoring in emergency situations, where a cheap, sturdy and simple device needing a minimum of maintenance and being easy to operate by relatively unskilled personnel is required. It consists of two cylindrical ionization cham bers, namely a measuring chamber and a compensating chamber mounted on top of it. They are charged at opposite polarity with r e spect to a common central electrode suspended by polystyrene insulators mounted on guard plates. The volume ratio of the two ch am bers can be adjusted to com plete com pensation. The potential difference is maintained by a transistorized DC con verter. The prim ary power source is two 1. 5-V flash light dry cells having a lifetim e of about 500 hours of continuous operation. The rate of discharge, when a sample is placed in a sample tray (of capacity 1 litre) under the end wall (1 mg/cm2 metallized polyester foil) of the measuring chamber, is counted by means of a direct-reading pocket dosimeter of the usual type. The sensitive volume of the two cham bers is very large (10 litres each). The count-rate will therefore be large, and the relative standard deviation sm all. F o r this reason it is possible to use the instrum ent without shielding in relativ ely 5 S ee Figs. V I. 2 and

119 FIG. VI. 2. Compensated ionization cham ber for em ergency food monitoring (A tom ic energy Commission - Denmark) large external gamma fields such as must be expected in a seriou s fall-ou t situation. A check source of MCi 36C1 is used for demonstration purposes. It gives the sam e deflection as a liquid sample of about pci/tnl, corresponding to half the usuallyaccepted concentration for a 30-d emergency period. The maximum sensitivity is about 200 pci/ml (corresponding to 1/20 full scale deflection per hour). 107

120 FIG. V I. 3. Compensated ionization cham ber for em ergency food monitoring (Atomic Energy Commission - Denmark) 108

121 A N N E X V II ENVIRONMENTAL MONITORING PROCEDURES ADOPTED IN PREVIOUS EMERGENCY SITUATIONS 1. A c c id e n t a t W indscale No. 1 P ile, U nited K ingdom, 10th O ctober, 1957 [32-34] The two original reactors at Windscale, known as No. 1 and No. 2 P ile s, were essentially graphite-m oderated, natural uranium fuelled reactors, cooled by a forced air draft. The coolant was exhausted through a filter bank fitted at the top of a 125-m stack. During a routine operation begun on 7th October, 1957, to release Wigner energy from the graphite, excess nuclear heating was wrongly applied causing the failure of a number of fuel cartridges. The uranium caught fire and the fire spread until it involved about 150 channels. Fissionproducts were released to the atm osphere from the stack. From measurements of air-borne activity and of activity deposited ujson the ground it has since been estim ated that approximately Ci 1311, Ci 132Te, 600 Ci 137C S, 80 Ci 89Sr and 2 Ci 90Sr were released. Some of this activity reached the continent of Europe. The first indication of an abnormal release of activity came through routine air-sam pling on the site. The a ir sample collected between a.m. and 2.00 p.m. on 10thOctober at a point about 800 m from the stack indicated a contamination level of dis/min per cubic m etre, about 10 times that normally resulting from the decay products of radon and thoron. The situation was confirmed by further air samples taken at other points on the site. The state of affairs in the reacto r was discovered by visual inspection. The firs t requirem ent was to determ ine gam m a-radiation levels in the d istrict around the W orks. A survey vehicle was therefore sent out at p.m. to make ground and air m easurem ents in the down-wind direction (south-east). A second vehicle le ft at 5 p. m. to explore the area north of the site. The radiation levels due to deposited activity were generally about mr/h in the area 3-5 km south of the Works 109

122 and much low er in other directions. There then appeared to be no significant external radiation hazard. Measurements continued during the period of release and it has been e s timated that the integrated exposure to any member of the public did not exceed 75 mr. Throughout the period of release some thousands of a ir samples were taken both on the site and in the nearby district. Although the air contamination rose on occasion to worrying, but not dangerous levels on the site, dilution resulting from wind variation considerably reduced the hazard in the district. A fter midday on 11th October air contamination levels both on and off site fell rapidly to well below the ICRP values for continuous exposure. By the evening of 11th October it was clear that there was no significant external radiation or inhalation hazard. Further planning was based on tne assumption that the relea se contained a normal distribution of mixed fission-products. The gamma-radiation survey results were therefore interpreted as indicating that there might be a m arginal risk from contam ination of m ilk with isotopes of iodine and strontium. Milk sam ples were collected from lo cal farm s during the evening milking on 10th October and the morning and evening milkings on 11th October. However, the analytical results were not available until noon 12th October. The milk collected on the evening of the 10th and morning of the 11th, in fact, contained only traces of radioiodine but that obtained on the afternoon of 11th October contained /uci/litre. The analyses revealed a higher proportion of radioiodine than would be present in a norm al reacto r fission-product mixture. It was evident that iodine vapour had passed through the stack filter but that the m ajor part of the particulate material had been retained. No perm issible level for 1311 in milk existed at that time. A group of experts was convened in the afternoon of 11th October and by p. m. the decision had been reached that distribution of milk should be prohibited if the 1311 concentration exceeded 0. 1 MCi/litre. Arrangem ents were made to prevent milk deliveries that night from 12 milk producers within a 3-km radius of W indscale. 110

123 On Sunday, 13th October, a widespread monitoring programme was initiated to delineate the areas over which an embargo on the consumption and sale of milk would be necessary. By 14th October, this restriction finally covered a coastal strip about 50 km long and about 500 km2 in area. It was soon found that considerable use could be made of the gamma-survey as a guide to the area from which milk samples were required. The bulk of the survey work was done with portable scintillation gamma-monitors designed for geological prospecting. These were found to have many advantages over the conventional ionization cham bers previously used for district surveys. Ground measurements, coupled with simple direct measurement of the 131I level in milk made by placing the detector head of the instrum ent in contact with the side of a milk churn, provided a screening technique for deciding the farm s or collecting centres from which milk should be sampled for m ore p re cise laboratory analyses. Fifteen vehicles, each with,a team of two men, were used to delineate the restricte d a reas and subsequently follow the trends of m ilk contamination until the restrictio n could be lifted. Altogether these team s collected over 2000 litres of milk, mainly in 250-m l sam ples. The analytical team s handled over 3000 sam ples. In addition to milk, other foodstuffs were monitored and during the occurrence of the survey over 1 tonne of vegetables, about 700 eggs and about 50 kg of meat were handled. Drinking water supplies in Cumberland, Lancashire and North Wales were also analysed. In all cases it was found that the level of contamination was well below that which would constitute a hazard. In vivo monitoring of the thyroid glands of selected adults and children demonstrated the efficacy of the remedial measures; the highest dose to a child's thyroid was estimated as 16 rads and to an adult's thyroid, 4 rads. Thyroid glands from sheep, cows and pigs were also examined, the maximum dose to an anim al's thyroid being estim ated to be le ss than 1000 rads (incurred by grazing sheep). By 4th November the only restricted area remaining was a coastal strip extending about 20 km southwards from Windscale. Ill

124 This area remained under restriction until 23rd November, by which tim e sufficient analyses of strontium in m ilk had been made for it to be certain that no restriction was necessary on account of 90Sr. In view of the possibility that some 90Sr might reside in the root mat and soil and find its way to grass and thence to milk at some later time, it was decided to examine grass and milk for this nuclide for an extended period and measurements went on, in fact, until late The early fears were not realized and by the late summer of 1958 there was no evidence of any contribution to radiostrontium contamination of m ilk from the accident. Twenty persons were employed in handling and recording the sam ples obtained during the period of intensive monitoring and assisting in the operation of a control centre where all information was recorded and displayed on maps. Some 150 radiochemists, distributed between the various U. K. A.E. A. establishm ents, contributed to the analytical effort. Several valuable lessons were learned from the accident which served to highlight the need for (a) authoritative and agreed exposure criteria for use in emergency situations, (b) portable, self-contained instrum ents of the required sensitivity for gamma-survey work, (c) means of obtaining assistance from outside sources to cope with the increased load on monitoring and, particularly, analytical fa cilities, and (d) a prepared plan of action with both local and cen tral government organizations. 2. Failure of the AERE effluent disposal pipe line, United Kingdom, 1st August 1961 [35] 112 A burst occurred four feet below ground in the 18-inch castiron pipeline used to carry liquid effluent of low activity from the Atomic Energy Research Establishment, Harwell, to the Tham es. Inactive trade waste was being discharged at the time but the resulting flood carried a small quantity of active sediment from the pipe over a road and into a nearby private house and some garages. The activity was established to be almost entirely 137Cs and it was estimated that le ss than 1 mci had been distributed over an area of roughly 200 m2.

125 A monitoring team of three men reached the contaminated area within 30 minutes of the occurrence being reported to the health ph ysicists. A rapid estim ate of the level of contamination was made using a standard portable contamination monitor (AERE Type 1320 fitted with a B. 12 /3-counter) and it was quickly established that there was no hazard from radioactivity. Sam ples of soil, silt and water were taken fo r rad io chem ical an aly sis and g am m a-sp ectro m etry. A more detailed survey was made the next day to identify any isolated areas of contamination. Instruments used included an AERE Type 1320 contamination monitor, Type 1368 and Type 1413 geological survey-m eters, and a prototype sensitive ionization chamber. Rem edial action consisted of decontamination of a ll a reas showing more than 10 counts/s on a standard (3-probe (roughly equivalent to 2 XlO"4 MCi/cm2). 3. Nuclear excursion at SL-1 reactor, National Reactor Testing Station (NRTS), Idaho Falls, Idaho, USA The m aterial which follows is summarized from the United States Atomic Energy Commission document IDO [36]. References to page, table, and figure numbers from that document are given in parentheses in this Annex. 3.1, Description of reactor The SL-1 was a direct cycle, boiling-water reactor of 3000 kw gross heat capacity with enriched uranium fuel, clad in aluminium, and moderated and cooled by light water in natural circulation. The reacto r was a prototype of a facility that could be operated at remote sites for three years without re fuelling. The reactor was located within the National Reactor Testing Station (NRTS) near Idaho F alls, Idaho, USA (Fig. 1.1, page 13) Description of accident A nuclear excursion occurred within the reacto r v esse l at p. m., January 3, 1961, resulting in the death of three persons, extensive damage to the reactor core and room, and 113

126 in high radiation levels (approximately 500 to 1000 R/h) within the reactor room. At the time of the explosion, which resulted from the nuclear excursion, the reactor was loaded with 40 fuel elements and 5 control-rod blades of cadmium. A three-man crew was on the top of the reactor reassembling the control-rod drive mechanisms and housing. The accident was caused by manual withdrawal, by one or more of the maintenance crew, of the central control-rod blade from the core, conside rably beyond the lim it specified in the maintenance procedure. Some gaseous fission-products, including radioactive iodine, escaped to the atmosphere outside the building and were c a r ried down-wind in a narrow plume. Particulate fissionproduct m aterial was largely confined to the reactor building, with slight radioactivity in the immediate vicinity of the building Environmental measurements Initial prediction of the trajectory of the plume from the accident site was based on winds m easured at the 250-ft level at the Central Facilities Area six m iles west of S L - l. The predicted trajectory was nearly straight southwest, passing over nearly inaccessible territory (Fig. 4. 2, page 73). Aerial survey techniques did not detect any activity above background radiation except in the immediate vicinity of the S L -1 site. Measurements made on sagebrush samples indicated that the plume had firs t travelled toward the south southeast for approxim ately 20 m iles before shifting toward the southwest (F ig s. A -3 and A -4, pages 134 and 135). The quantity of 131I released from SL.-1 was estim ated from measurements obtained on sagebrush samples and on appropriate m eteorological assumptions (Table A - l, page 131). On this b a sis, 10 Ci of 131I had becom e air-borne by m id - morning of January 4, 1961, 20 Ci had become air-borne 24 hours la te r, and at le a st another 50 Ci of 131I had been released between January 6 and 30, Aerial survey 114 The aerial survey equipment included a battery-operated Nal scintillation detector, a logarithm ic count-rate m eter, and

127 a recording chart. The first post-incident flight was made at 6.35 a.m. January 4, Subsequent flights were made on January 7, 8, and 12, 1961 (Figs through 4.5, pages 72 through 76). Only m inor activity peaks (approximately 100 counts/s above a 200 counts/s background) were detected outside of the immediate area of the SL-1 on January 7, Only one spot of ground contamination, approximately three m iles south of S L -1, was found on successive flights, while the location of other peaks was dependent upon the prevailing wind at the time of the survey Vegetation sampling Starting on January 4, samples of sagebrush were collected along roadways in the region south of the SL-1 site. Sampling was then extended in directions determined by the results of the initial sam ples. Sagebrush sam ples were analysed by gross gamma-counting of a g portion in a Nal wellcry sta l. G am m a-activity on sagebrush sam ples had been about 1-3 counts/min per gram in D ecem ber, The post-incident measurements ranged from 104 counts/min per gram directly south of SL-1 to approximately 102 counts/min per gram in the region between Atomic City and Taber (Figs and 4.8, pages 78 and 79). G am m a-spectra from representative sam ples indicated the majority of the activity on sagebrush was due to 131I. Specific analyses for 13? indicated a maximum concentration of 105 pci/g approximately 100 yards south of S L -1, and a general level of 102 pci/g between Atomic City and approximately 40 miles south of Atomic City (Table 4. 1, page 62). The area of effluent deposition, approximated from the r e sults of sagebrush sampling through January 7, 1961, is given in Table VII. 1 (page 56 and Figs. A-5 through A-7, pages 136 through 138) Milk sampling Twenty-eight milk samples were collected from the region 20 miles south of the SL- 1 site, which contained the closest dairy farms lying in the path of the plume (Fig. 4. 8, page 79). 115

128 Only six of the samples contained 131J significantly above the detection level (Table 4.5, page 67). These sam ples were collected between January 8 and 11, 1961 and ranged from 160 to 280 pci of 131I per litre of milk. TABLE VII. 1 EFFLUEN T DEPOSITION Distance from SL-1 area (miles) Width of deposition pattern (miles) (NRTS boundary) Air sampling Air-borne concentrations of radioactive m aterials were measured at numerous locations using sam plers consisting of a sm all cartridge of activated carbon for i31i collection plus a p re -filte r for particulate collection. The results of the samples collected at Atomic City, the clo sest off-site community to the SL -1 site, indicated a maximum of 40 pci 131I per m 3 a ir during the period from January 3 to 9, 1961 (Table 4.7, page 69 and Fig , page 85). Potential thyroid doses received by residents of Atomic City were calculated from the measured air concentrations of 1311 and "standard man" parameters to be less than 35 mrad. 13il concentrations in the immediate vicinity of SL-1 reached 102 pci/m3 on typical days during the second week after the accident (T able4.8, page 70 and Fig , page 86) Gamma-radiation measurements 116 Film badge dosim eters are routinely placed at 313 locations throughout the NRTS to record gamma-radiation doses. Four-

129 teen d osim eters in the v icin ity of SL -1 w ere changed on D ecem ber 1, 1960 and again at various tim es after the incident. Eight of th ese located approxim ately one m ile south and southw est of SL -1 had recorded gam m a-radiation ex p osu res of 40 to 50 m R when changed on January 4, Four dosim eters, located at each corner of the SL-1 fenced a rea, w ere changed three to four w eeks after the incident. These four had recorded exposures of 420 to 580 R (Fig. 4.13, page 84). On January 5, 1961, 28 stations w ere establish ed around the SL-1 area fence where repetitive gam m a exposure-rate m easurem ents could be made at varying distances arid directions from the reactor (Fig , page 88). The resu lts of these m easurem ents indicated that gamma exposure-rates consistently decreased with about a one month half-life. Typical readings are given in Table VII. 2 (Fig , page 89). TABLE VII. 2 GAMMA EXPOSURE-RATES Distance NE o f SL-1 reactor building (ft) Date Gamma exposure-rate (mr/h)

130 R E F E R E N C E S [1 ] RADIOLOGICAL HEALTH HANDBOOK, Rev. ed., US Dept, of Health, Education and W elfare, Washington 25 D.C. (1960) 9798 pp. [2 ] BEA TTIE, J. R., An assessment of environm ental hazards from fission product releases, U.K.A.E.A. rep. AHSB(S) R 64 (1963). [3 ] BLOMKE, J.O., TODD, M.F., U ranium -235 fission product production as a function of thermal neutron flux, irradiation tim e and decay tim e, Part I, 1 and 2 USAEC rep. TID-4500 (13th ed.) (1957). [4 ] BOLLES, R.C., BALLOU, N.E., Calculated activities and abundance of UZ35 fission products, USNRDL-456 (1956). [ 5 ] LA V IE, JrM., DOURY, A., «E v a lu a tio n des risques rad ioactifs lies au fon ction n em en t d une installation nucl6aire», CEA rep.no. 1724, Centre deludes nucl^aires de Saclay, France (1960). [6 ] BRYANT, P.M., Methods o f estim ation of the dispersion o f windborne m aterial and data to assist in their application, U.K.A.E.A. rep. AHSB (RP) R 42 (1964). [7 ] WATSON, E.C., GAMERTSFELDER, C.C., "Environm ental rad ioactiv e contam ination as a factor in nuclear facility site selection, Siting of Reactors and N uclear Research Centres, IAEA, Vienna (1963). [8 ] GARNER, R.J., private communication. [9 ] OKONSKI, J., LENGEiMANN, F., COMAR, C.L., Hlth Phys. 6 (1961) 27. [1 0 ] COMAR, C. L., DRIGGERS, J.C., Science 109 (1949) 282. [1 1 ] EKMAN, L., A cta vet. scand. 2 Suppl. 4 (1961). [12] MAHMOUD, K. A., "An approach to relevant dose computations from environmental contam ination ", Selected Topics in Radiation Dosimetry, IAEA, Vienna (1961) 85. [1 3 ] CHAMBERLAIN, A.C., GARNER, R.J., WILLIAMS, D., Environm ental m onitoring after accidental deposition of radioactivity, Reactor Sci. Technol. 14 (1961) 155. [1 4 ] COOK, J. E.. Evaluation for emergency planning o f hazards from accidents involving stocks of radioactive m aterials, Hlth Phys (1964) [1 5 ] COMMITTEE ON PROTECTION AGAINST IONIZING RADIATIONS, Report to the M edical Research Council,M axim um perm issible contam ination o f respirable air after an accid en tal re lea se o f rad io io d in e, radiostrontium and c a e s iu m , Br. m ed. J. N o ( ) [1 6 ] COM MITTEE ON PROTECTION AGAINST IONIZING RADIATIONS, Report to th e M edical Research C ouncil, Maximum permissible dietary contam ination after the accid en tal release of radioactive materials from a nuclear reactor, Br. med. J. 1 (1959) [1 7 ] CAVELL, I.W., PEABODY, C.O., The Winfrith district gamma survey, U.K.A.E.A. rep. AEEW-R62 (1961). [1 8 ] LISTER, B. A.J., The use o f helicopters for em ergency district survey after an accid en tal release of radioactive m aterials, Hlth Phys. 9 (19t& ) 309. [19] BOULENGER, R., MAERE, X. de, OSIPENCO, A., «Prospection radiologique par helicoptere applicable & un rejet atmosph rique accid en tel de produits de fission dans la region de M o l», Paper presented at Colloquium on Radioactive Pollution o f Gaseous M edia, S a cla y, France ( Nov. 1963). [2 0 ] W ILUAM S, D., DERRY, K.E.G., "G am m a spectrom etry from a v e h ic le ". Proc. Sym p. Environmental M onitoring, Berkeley, England (1963), Pergamon Press, London. 118

131 [2 1 ] HOWELLS, H., "Assessm ent o f an em ergency situation: organization o f th e em erg ency environm ental survey" WHO/FAO/IAEA Sem inar on Protection o f the Public in th e Event of Radiation A ccidents, Geneva (1963). [22] SOLDAT, S. K., private com m unication. [2 3 ] RISING, F.L., unpublished work. [24] McCONNON, D., Calibration o f survey meters for field determ ination o f I131 in m ilk, Note to file. [2 5 ] UNITED STATES ATOMIC ENERGY COMMISSION, A m anual o f em ergency procedures for environmental m onitoring,. (McCONNON, D., Ed.) H W [26] HOLT. F. E., Emergency radiological plans and procedures, (HEID, K.R., Ed.) USAEC rep. HW (1962). [2 7 ] HEALTH and SAFETY LABORATORY, Manual of standard procedures, USAEC rep. NYO-4700 (Rev.) (1964). [281 WORLD HEALTH ORGANIZATION, Methods o f radiochem ical analysis; WHO T ech n ical Reports Series No. 173, Report of a Joint WHO/FAO Expert Com mittee (1959). [29] AARKROG, A., private communication. [30] HOLT, F.E., private communication. [31] DOURY, A., MONET. I., «Statio n mobile de surveillance atmosphsrique», Centre d* tudes nucteaires de Saclay, France (1964). [3 2 ] "A ccident at Windscale No. 1 Pile on 10 October 1957", Comnd. 3 02, H.M.S. O., London (1957). [3 3 ] DUNSTER, H.J., HOWELLS, H., TEMPLETON, W. L., "D istrict surveys following the W indscale incident". Proc. 2nd UN Int. Conf. PUAE 18 (1958) [34] LOUTIT, J.F., MARLEY, W.G., RUSSEL, R. S., The nuclear accident at Windscale - October 1957: Environmental aspects, Comnd H. M. S. O., London (1960). [35] GARNER, R.J., private communication. in the Hazards to Man of Nuclear and Allied Radiations [3 6 ] IDO Report on the N uclear Incident at the SL -1 Reactor, January 3, 1961, at the N ational Reactor Testing Station, ID O BIBLIOGRAPHY ALDERHOUT, J. J. H., MOEKEN, H. H., The long-term average atmospheric dilution of emissions from a chimney in the Mol area. Int. J. Air, Water Pollution j> (1962) ATEN, A.H.W. Jr., UMANS, H.J.L., DeJONG, W.M.C., m ilk after a nuclear accid en t; Hlth Phys. 4 1 (1960). Determination of radioiodine in BEATTIE, J. R., "Future trends in the assessment of hazards from fission product releases, Colloquium on Radioactive Pollution of Gaseous Media, Saclay, France (1963). BOVARD, P., GRAUBY, A.. «L a surveillance hydrologique syst6matique», Bulletin dtnformation Scientifique et Technique, No. 70, Centre d*6tudes nucl aires de Saclay, France (1963). CHAMBERLAIN, A.C., Relation between deposited activ ity after the W indscale accid en t o f October 1957, U.K.A.E.R. rep. AERE - HP/R (1958). 119

132 CUFFORD. C.E.. Effects of ground roughness of the gamma dose from C s151, AEC ren. DRCL-401, Canada (1963). CUFFORD. C. E.. CARRUTHERS, J. A.. CUNNINGHAM, J. R.. a simulated fall-out filed using C s«, AEC rep. DRCL-296, Canada (1959). Scatter gam m a radiation from COMMITTEE ON RADIOACTIVITY MEASUREMENT, Radiation C ouncil, Japan, o f radioactive strontium (1963), Determination of caesium -137 (1963). Determination CROUTHAMEL, D. E., Applied gamma-ray spectroscopy, Pergamon Press (1960). DAVIS, F. J., REINHARDT, P. W., Phys. 8 (1962) Radiation measurements over simulated plane sources, Hlth DORRESTEIN, R., "A method of computing the spreading o f m atter in the water o f an estuary, Disposal of Radioactive Wastes II IAEA, Vienna (1960) 163. DOURY, A., «M t orolog ie et contrsle des radiations en atmosph&re libre au voisinage d'un site n u cl a ire», Bulletin d'inform ation Scientifique et Technique,N o. 64, Centre d' tudes nuclgaires de Saclay, France (1962). DUMMER, I. E., J r., Evaluation of SrM -Y surface contamination using radiation survey instrum ents, LA DC-4467, USA (1964). FERGUSON, J. M., Ground roughness effect for fallout contamination: comparison of measurements and calculations. USNRDL-TR-645, USA (1963). FIELDS, R. E., Deposition v elo cities o f airborne fission products, Convair Report FZM 1985, USA (1960). GARNER, R. J., "'Monitoring programmes in em ergency situations", FAO/WHO/IAEA Sem in ar, Scheveningen, Netherlands (1961). GIFFORD, F. A., Atmospheric dispersion calculation using the generalized Gaussian plume m o d e,. Nucl. Saf. 1 3 (1960) GIFFORD, F. A., Use o f routine meteorological observations for estimating atmospheric dispersion; Nucl. Saf. 2 4 (1960) GREEK, G.E., MARTIN, W.J., PARKER, G.W., from molten uranium fuels, USAEC rep. ORNL-2616 (1959). Experiments on the release o f fission products HAND, J. E., GUILLOU, R. B., DORELLA, H. M., 4 ( ). Aerial radiological monitoring system, CEX-59 HEALTH AND SAFETY LABORATORY, Manual o f standard procedures, USAEC rep. N YO-4700 (R e v.). 120

133 HILSME3ER, W.F., GIFFORD, F.A., Graphs for estim ating atm ospheric dispersion, ORO-545 (1962) HOWELLS, H., "Assessment of an emergency situation: organization of the emergency environm ental survey", Proceedings o f WHO/FAO/IAEA Seminar on Protection of the Public in the Event of Radiation Accidents, WHO, Geneva (1965). INTERNATIONAL ATOMIC ENERGY AGENCY, Waste disposal into the sea. Safety Series No. 5. IAEA, Vienna (1961) 165 pp. INVESTIGATION COM M ITTEE OF METEOROLOGY AND ATOM IC ENERGY, on atmospheric dispersion and deposition,. JaDan (1962) Sum m ary report JAPAN ATOMIC ENERGY RESEARCH INSTITUTE, Exposure from contaminated atmosphere dispersed in em ergency situation following a reactor accident, 5003 (1961) and JAPAN ATOMIC ENERGY RESEARCH IN STITUTE, orology, 5002 ( 1960) Observation and investigation of oceanom ete- KIEFER, H., MAUSHART, R., "M easurement in successive stages o f an em ergency: equipm ent, methods and fa c ilitie s ", Proceedings o f WHO/FAO/IAEA Sem inar on Protection o f the Public in the Event of Radiation Accidents, WHO, Geneva (1965) LINDEKEN, C. L. et a l., Hlth Phys.9 (1963) Collection efficiency of W hatman-41 filter paper for submicron aerosols, LODGE, J.P. et al., The use of impregnated filters to co llect traces of gases in the atmosphere. 1. Suitability of membrane filters i Ind. Hygiene J. 24(1963) MATHER, R. L., JOHNSTON, R.F., TOMNOVEC, F.M., contaminated ground', Hlth Phys. 8 (1962) Gamma radiation field above fallout \ MEADE, P.J., M eteorological aspect's o f the peaceful uses o f atom ic energy WMO T ech n ical Note No. 33, Part I, MOTTEFF, J., Energy spectrum of gammas from fission products, Nucleonics 13 (5) (1955) PASQUILL, F., The estim ation of the dispersion of windborne m aterial, M eteorol. Mag. 90 (1961) PASQUILL, F., "Atmospheric diffusion", D. van Nostrand (1962) PEIRSON, D. H., The interpretation of gamma-ray scintillation spectra from fission product mixtures,. Brit. J. appl. Phys. 11 (1960) PRICE, J.R., Evaluation of rapid aerial radiological survey techniques> W T -758, USA (1954). 121

134 PRIESTLEY, C. M. B., Turbulent transfer in the lower a tm o s p h e re U n iv. of Chicago Press (1953) RDC 1-3, "Radioactivity survey of the m id-pacific area" (1962), Japan (1963), SANDERS, F.H., USAEC rep. HW (1963). Estimation of radioactive surface contamination by radiation survey instruments, SCHIAGER, K. J., ALLEN, T. M., GERBER, G.E., KROUPK, F. J., REILLY, D.W., Improved m em brane-filter air sampling methods for environmental control, Hlth Phys. 2 (1960) SCHONFELD, J. C., Diffusion by homogeneous isotropic turbulence* Rijksw aterstaat, W ater resources and hydraulic research, Report F a SIEVERT, R. M., "Planning an organization for radiation em ergencies (with special reference to Sweden)", Proceedings o f WHO/FAO/IAEA Sem inar on Protection of th e Public in th e Event o f Radiation A ccidents, WHO, Geneva (1965). SILL, C. W., FLYGARE, J. K., Phys. 2 (1960) Iodine monitoring at the National Reactor Testing Statio n, Hlth SUTTON, O,G., Micrometeorology, McGraw-Hill (1953) T A IT, G.W.C., MERRITT, W.F., Phys. 1 2 (1958) Emergency radiation monitoring of drinking w ate r, Hlth UNITED KINGDOM ATOMIC ENERGY AUTHORITY, No. E. 3.1, Issue No. 1 (1960). " S ite em ergency co n tro l", Authority Code WEATHER BUREAU, US Dept of Commerce, "Meteorology and Atomic Energy", AECU-3066 (1955), WHITE, J. M., NEIL, J., Pre-planning for nuclear accidents; Hlth Phys. 9 (1963) 507. YAMASHITA, M., WATANABE, H., A y ray spectrometric method for the measurement on fallout contaminated samples, J. Atomic Energy Soc., Japan, 5 10 (1963) ). 122

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