PRE- AND POST-MARKET MEASUREMENTS OF GAMMA RADIATION AND RADON EMANATION FROM A LARGE SAMPLE OF DECORATIVE GRANITES ABSTRACT

Transcription

1 RE- AD OST-MARKET MEASUREMETS OF GAMMA RADIATIO AD RADO EMAATIO FROM A LARGE SAMLE OF DECORATIVE GRAITES Da J. Sck 1 hyc Da, S. Jh Uvy Cgv, M ABSTRACT R ada ga c gad c h a x xa gaa ada ad a x ad dcay dc cad y dg aa. Th gaa ada, adcd c ad ac d a w ad 322 a 254 ad y (aa ~5 2 a) ad 14 a a (aa ~1 2 ). Avag ac gaa d a agd 1 24 µ h -1 wh h 16 µ h -1. Rad aa, ad 6 a 24 ad y, agd 1 4 C -2 h -1. Eaa ac agd ghy 5% 5%. Idvda ag h a hwd aa a a hgh a 13 C -2 h -1. Md caca gg ha h cca gh cv d ha waa da ac wh aa aa y ga a ad a, ay vad vg ac. Bad h, -ak cg c hav dvd ad a g d v ay ac a vy. -ak cg a a g d a dy 35 h. Th ax ad aa ad ga 11 h wa 9 C -2 h -1. ITRODUCTIO Mda ada ga c cy gad c h. Wh ay dg aa dvd ck ha h a ca ada x, aa dcav k ga ca hav vad cca aay-ccg adacv aa (ORM). Th 238 U ay, ad a x h 232 Th ay, ca w ahway x. I add xa ada d gaa ay, h a hav a whch a adacv ga ha ca ca h ck ax h v. Th ga, d a ad ad h cvy, dcay chcay acv dcay dc ha ca dv a ada d wh had. C yg dcav ga, ad dy ha h, wa a aw a dcvy q, I a? Th a a dyg ha h a a aw ha q. Th ay vy ca h h aw h q ak da. F xa, wh c hah ca gh a h ay g h avag ac h ada x h ga a, dvda a ay ccd a h 1 Th wk wa d, a, y a ga h CSB/SJU acy dv ga. 28

2 w cc x. A dc ha gh dd avy a ga, gh jdgd y a cc c wh h dc ad ad-vy a h day. Th, a ak a a dc ay d cd h jdg v, y aa c. Th wg gdg hhy -ak cg wa dvd hgh dc wh h d Cd Sg Ga C. 2 (CSG). W wad d ad a cd c c ga c ha gh ga ada x dd a hgh ha ay cd a. W wad a aa c cd ha h dc wa a wh d a a aca. Tha d qd h dv a c-cv hd dy dc ha ay ( ay cvd ) ca a xc ada k h c, h CSG c c vy g h dca ad a hd, ay h dca hd a cg ck xg y, ad ay h a hd w y ha ay addd h dc. Sc h a chv da (US) ga ORM x, h cda aa ad aa ada c gaza w add a h c ay adad. Th cda a ad h cv aa d a dvda ca c (HS, 29). I h wk, h d wa cacad a dvda a hgh, axa, x ca. I add, h d a avag yca aa wa cacad a h c hah ac dcav ga. A, v a had ad ga a g d h US a c, dk, g ad wa. Th ada chaacc y a w dz h hav d h a (K, 25, 28, 29; Bdhad, 28) ad h c (EH&E, 28). Bad h ay, ca ha ay h hgh ada ga hw aa vaa h ada chaacc. Wh h dv d h aa dy ad c d, h ga h jc w aay xad h aayzd adacv ad ad ada x. Tha qd h dv a hd ad dcv d a a h xa gaa ada d ad a ad-ad d h y y (-ak) h h (-ak). MATERIALS AD METHODS Tw dc a ad c w dd h d, v, ad caa h dy ad c. A hgh v chca k ad c a avaa h dy ag ada a ha hav cd y czd ad ad. Hwv, hy ay 2 Cd Sg Ga Cay Ga W Rad Cd Sg, M

3 hav h qcky ha a h h ca h ag ha ay d d. -ak a ad c Ca ha h qay, c dcav gay hav a ca acy wh h aa ca ad wh g cd, h h h a h cvg dck wah. Th v gg ha a cv a gh y a a ha caa qck, c c vga adcd c ad x ddg h h c ad/ v xc wh h aca y. Th h a ad a aach dcd h a. Ga a ad a Dcav ga c aa a ay qad ag ck ad h c ad cd a ha a ghy 5 6 wd y ~ g. Wh a a 3 c hck, a a h a 2 c. Dcav ga wa a ay 1 2 c hck. O d h ga hd a g cad wh a qd y whch ckd cack ad cvc y ayg a da ac h a. S ha a ky cack a cvd wh a y ha gd h hd d. A a a vy h 254 y h 28-9 CSG vy wa cd gaa d a ad adcd c dg h d Oc 28 May 29. Sa a y whch w cd ad h ada w a aayzd. Th hd ac aa h a wa axay 1 2. Tw h a h c CSG vy (CK8 ad LD8) w h a y ha had aayzd wy ya a (Sck, 1988). Th had hw h hgh ada a h v aayzd O h a (CK88) wa h aca ha had ad Th CSG a, a qad d h Aca, had y ccd dvda ca hy dayd hgh adacvy dg cg. Gaa d a cg S gaa ay c, ay ca G-M dc, vd h qck ad a ada a ha ca ad. Hwv hy d away gv a acca a h aca cv gaa d a ca h gy dda h dc ay d ha. h, ca ad caa a d, hy ca -cg ga. W d w ca vy c; h Ld 12S c R 3, ad h a M173 4 a qck -cg dvc. Th dc a hw h gh Fg 1. Th Ld h gh a. Th -cg dc ay gv a acca a h cv d a a xd c adcd k ga. Th aay ccg aa (ORM) ada h ay a; h a-ad (U-R) ay, h h-h (Th-T) ay, ad 4 K. Th gy 3 Ld Ma, Ic. 51 Oak S Swwa, Txa USA 4 OLIMASTER Ld. 112 M. Bgdavch. Mk, 224, Rc Ba 3

4 c ga gad ca aa q d h c h c ( 137 C) ha ay d caa h dc. O h a ca aa wh a a k h Th Scc (TS) Mc R T Eqva Svy M 5 hw Fg 1 h -. Ah acay a h a c h dc ad wa ad chaacc caca h cv d a k h Caa Ic (I1k) 6 hw h -a Fg 1. Fg 1 Sca-ad gaa dc d -cg Fg 2 Th av h h cad h TS. Fg 2 hw h av h dc wh xd d-y-d h ac h a Ca Gd ga hw Fg 1. Th ca w va dc ay gd gh d -cg. S h vaa d h aca aa vaa h gaa ada wh h aa 5 Th Fh Scc Ic. 81 Wya S Waha, MA Caa Id, Ic. 8 Rach akway, Md, CT 645, U.S.A. 31

5 cvd y h dc aay. Hwv, h h cv a ha h adg h Ld 12S ad h M173 wd d cvd g h cv g cv g aa a cv d a. I h wk, a w cd gaa d a y acg h h TS h I1k cac wh a h hd ac, wag ghy 12 h d cdg h adg. Sc h dc h ac aw a cv aa a 1 qa, adg w ak ach a a 5 ca 1 va. Ug h cd, k ghy c ach a. A d a d h a a ackgd ccd. I h a wah h ackgd wa axay 5 µ h -1 (5 Sv h -1 ). Gaa d a aa vaa Th I1k wa d a d a h ac ad h ac wh 3 w hza a; a ha wa ad ch ad ah a ha wa h ch (hw Fg 1). Th gd w aad y 1 3 h hza ad vca dc xc a.5 av h ac ad ag h dg h a. Th gd daa wa aayzd y SURFER g a kgg cd gv va a a gd wh 3 h hza ac. Th gd va w aayzd d hza ad vca c ha d h aa vaa. Th c w h d ga h d v h ac ccd y a dvda wh x wa g dd. Gaa adcd c Sccc cg a w ad h a g h I1k wh a 2x2 azd ai dc ad G 2 aay wa a a d a qck ad xv way a h ad gag a ga. Th hyh wa ha ad aa wa w gh cad wh h U ay c h aa ha wd v a a ga ad x. Sva aach w d caa h dc ccy h ad gy d-gad (+2%) c ad accacy h adcd c avagd v h a. Th h d h dca ad aay ay h ORM ak ay d aay aay. Th hgh gy ak ach ay w d chaacz h ay adcd c. Sc h ak gd ad ad h gy h U ad Th a, h a ad a ad, h gy c ad ad h gad h a ca ca dcayg gy. Gv h h ha- h, vd ha h ca d h ga h h c dd a h gy hd a gd axa h h ay cca. Tha a ay hd h ad gy a ga ddg h y, acg ad cag h ga. Th ccy -dc wa caad wh a cd. Th dc ccy wa cacad h ad gy ak g a IST-aca ad adad a a vay ca wh a qa ac ca. Th h h ak ccy wa ghy adjd y ag a CK88 wh adcd cca had dd y a IST-adad caad HG c

6 Gaa x d I kg wh h ada c hhy dcd av, h x dvda xa gaa ada wa ad g aa ha wd ad vad, axa d. F xa, d ad ha h x a ad h wk ca gy wh h hgh ada h a ( h ) wa cd a h dg h dk wk aa. B h wk y 4 h wk 48 wk a ha dk. Th, h a a y gh axa ad h cay h va ak acc wh cag h d cda. Th aca x dvda xa gaa ada wa cacad a d d h gy h -c x cd ad h gaa d d ccd ad ac gaa d a a dcd av. Tw x d w d a h aa d c: (1) a kch wk wh 4 h day wh 3 a hza c ad (2) a h wk wh 4 h wk g a a dk ha had a h a h wk aa. Tw h d w d a h aa d ad wa a : (1) a wk adg a ga 8 h day, ad (2) a yg 2 av h ad 2 a ga wa 8 h day. Rad aa a ad a A a y had cd adcd c, h wh h hgh a ad gy w cd ad aa a. Bh h hd ad hd d w ad ca hy a h aa yca ga aa. A v dy had ggd ha h gh d aa a h d ac (Bdhad, 28). Sc a ay vca a wa h cv way a ad h wah, aa acca had dgd adh hd, d, ad gh ac. Thy a had ad ak. Fg 3 hw a yca aa a g ad a hd ad a d ac. Fg 3: Eaa a a. Th a h a xa a g gd h -hd d. A a v ca w ad ach a; h hd d ad h h h d. A ca h hd d, a c ad 7 7 Rad Sc SARAD GH Wad Saß 1159 Dd GERMAY 33

7 (CRM) wa cd y a 4.6L acca whch cvd A a h h ca, c cha 8 (EIC) w cd y acca whch w 3L a w whch cvd Th ad aa wa y a 5% h a ac aa h a. Th a ga a w ad wh acca cd h a ha cvd 2 4% h ac. A w gad EIC-ad ad x (RFM) wa a d a h a. Th x ca cacad y h gwh h ad a acca ad y h CRM g qa 1: ( FA)! k T C( R) = (1! ) (1) Vk wh: T h acca F h ad x A h aa g h acca V h a v h acca k h cv a ad (Th ca c dcay, 7.55x -3 h -1, ak) C(R) h ad cca a ay acca T Sc acca x q a kw cv a, x w d d a y ha cad a gd, dc a w h acca ad h va ac h a. Wh adhv cay wa acca hd d, h gh ad d d qd a qck-g, adhv ag wh h cay hd ad a h acca h ac. Fg 4 hw a gwh cv wh a wghd a qa d h cv a ad a aky acca R C/L Fg 4 Rad gwh a acca wh a gh ak. 8 RAD ELEC Rad Ec, Ic A Idy La Fdck, Mayad

8 Oc h cv a kw, h h ad cca dg h a gwh ca ccd ad d a agh wh ca d caca h x. Fg 5 hw a yca 22 h gwh a CRM-a w h hd ac a ga a. Fg 5: Tyca gwh a 5L acca aachd ga wh h Rad Sc. S d d aa a Sa a ca ad ay ha a a h acca ca c h a ad a h aa a ac ay. Ga a aa w ad a w ad 24 L a ca. Bw y acca w d a h aa ach d ach a. F gag dc k EIC ATD acca, h x ca cacad h avag ad g qa 2. ( FA ) -kt &, 1- )# < C( R) >= $ 1- * '! (2) Vk % + kt (" wh: T h acca F h ad x A h aa g h acca V h a v h acca k h cv a ad. Th ca c dcay (7.55E-3 h -1 ) ak <C(R)> h avag ad cca dg h acca T Each acca y wa caad g IST aa c (SRM ad ) (Kaa 25 Vkvk, 26). Adda da h ac ad caa h acca y ca d ah a h Sy (Kaa 29A). 35

9 Rad Ex ad d d Th hgh x ca, cad h cvav ca, ac a h aa k vg ac aa, ccacy ac ad va a. A d wa d a h ad cca gad y ga d a vay way d. Th d ad c xg h c h vg ac. Th h a d aa w ak h EA x ac hadk (EA, 1997) ca a ac cvav a x a a (64 2 ) ay vad (.35 ach) vg ac. Th aa ad x wa cvd cv d g h d cv ac USCEAR 26 ad yca hgh ccacy a. Th cv wa ghy a ya x 1 C L -1. Th aa d wa a cacad a yca d h wh a aa 3 2 ad a va a.2 ach a h c hah ac ga c a. -ak h a ad c Th ad cd d a h ada ac ga aady ad h hav q chca k ad c cv ha h h -ak v. S gaa d ad aa a y w dvd ad d ha kd hw cd dy h dc ad ak a. A dy a a cd vd h dway, g cd ad a hd hy a acca ad ag -ak ada x ga. Thy-v hw, y Ma, vd hav h h ad ga d ad. Th c ca w ha h h wa a ad gh ad had a aa aa xc ga. Th a c cdd cva ad a a h wh h ga wa, a ha wa ay ga, ad a a, h h had. AChk 9 h- k w xd 4 day d cd h cd. Lada RADTRAK dc w ay dyd a 9 day ( g) x d a vg cd. A wy dvd ad aa a y wa d a h ad aa a w ca ach y ga h h. Th aa y cd a hgh vy ad-h dcag ack dc d a ad-ag ha cvd Th ack ga dc ha dcd a (Sck, 26). Th ad x a gag dc k h ca ad h avag ad cca ad y h dc ad qa 2. Th ca aa a h ga ac w cd a h ac wa wy cad gaa acvy g h M173. Eaa a w ad a h ca h hgh gaa adg ad a avag gaa ca. Th aa y cv a (k) wa ad g h Rad Sc ad vd aay c. Th ack ga a ad 9 A Chk, Ic B Bdg Rd M Rv, C Lada 2 Scc Rad Gwd, I

10 wa caad wh a IST SRM4794 c. Th h h dc h aa ha y caad. RESULTS -ak a a a Ta 1 vd a ay h -ak a a c. Ta 1: Say -ak a cg a ad cd MEASUREMET ISTRUMETS Sa ad Gaa D Sc (GDS) Gaa Rad gy Aay (GRA) Rad Sac Eaa (RSE) TS c Caa Ic Caa Ic + G 2 wa RAD ELEC EIC 3L acca Rad Sc CRM 5L acca 322 a 254 y (c c vy y) a 5 a ca aad y ~1 a 12 ca 322 a 254 y a 5 a ca aad y ~1 a 12 ca; 5 a aay 6 a 24 y* a7 ca (4, 3 ack) 3 4 qa ad 24 h *22 h y w cd hav hgh ad a ad cg ad da Ta 2 gv h aca ay h gaa d a, a adcd cca, ad ad aa avagd ac h a. Ta 2 : Saca aa a-avag a MEASUREMET () Mda Rag Sa vaa Gaa d a(322) 4.3 µ h -1 Ra ad gy (322) (43 Sv h -1 ) 84 Bq kg -1 (2.3 C g -1 ) 1 24 µ h -1 ( 24 Sv h -1 ) < 23 Bq kg -1 (.3 62 C g -1 ) % da 75% ag Ra h gy (322) Rad Sac Eaa (6) 48 Bq kg -1 (1.3 C g -1 ) 62 C -2 h -1 (24 Bq -2 h -1 ) < 13 Bq kg -1 (.3 35 C g -1 ) 3 3 C -2 h -1 ( Bq -2 h -1 ) 36% da 12% ag Eaa ac(6) 22% 3 59% 37

11 -ak gaa ada da Gaa D Sc (GDS) Fg 6 hw h gaa ada d a avagd ac dvda a. Idvda ag agd a a ax 8 µ h -1 (ackgd acd) Sac D a c/h Fg 6 Mad gaa ada d a avagd ac h a ac. (Th va a hw h vca ca wh h ac h a va hw h vca ca.) Gaa Rad gy Aay (GRA) Fg 7 hw h avag gy cca ha a h a h ad ad h. F h a a a g, a ad gy avagd 2 Bq kg -1 (5.7 C g -1 ) ad agd 23 Bq kg -1 (62 C g -1 ). Ra h gy avagd 9 Bq kg - 1 (2.4 C g -1 )ad agd 13 Bq kg -1 (35 C g -1 ). a Ra gy cca Bq/kg B a Ra gy cca Bq/kg Fg 7 Ra gy cca ad a: ad () ad h (gh) B 38

12 Fg 8 hw h ac h d cad y ach ORM ay g h cc h c d y ay d h Ea C 112 (EC 1999) ad h dvda cca ad dvda a. I whwh h aa a wh ad gy ak h k h d ad h aa wh h ad gy c. Th avag c y ay a: U/R 33 %, Th/T 24 %, K4: 43 %. a Fac d a Fac d B B B Fg 8 Rav c ac d ORM a 238 U, 232 Th, ad 4 K a Fac d -ak gaa d a aa vaa ad x Fg 9 hw h a aay h ad aa vaa h ackgd acd gaa d a ad a a Ca Gd. Fg 9 Gaa d a c a h h vcy h Ca Gd a (Fg 1) ay x aay g h d a a a gg ha a c wd hav hav a avag ac gaa d a µ h -1 av ackgd xcd h x cda h kch wk. I h dk wk x ca, h h wd hav xcd 6 µ h -1. I h ca x ad wa g aa, h a avag ac d a a w; 33 µ h -1 39

13 adg- ca, 29 µ h -1 h g ca, ad 13 µ h -1 h g-wa ca. -ak Rad Sac Eaa (RSE) Th da va h a-avag ad aa h 6 a ad wa 24 Bq -2 h -1 ( 62 C -2 h -1 ). Fx agd Bq -2 h -1 (3 3 C -2 h -1 ). Fg hw h x d h a. a R Fx Bq/^2 h Fg Sa avag ad x d h 6 a.2.1. Th ad aa ac ca cacad h ad ad x ad h a ad gy dd y gaa ccy a dcd h Mhd c. Th aa ac d had a da va 22% wh a ag 3 59%. F dvda a, h x vaa ac h hd d hwd a da vaa 6% a dd h vaa ac h hd d. B h x wa q d h hd h hd d. I aca a ha had g gd h hd d ay hwd x w h dc. B 4 22 ch a had a qa x h d. Say, wh a wh ad (gh) ack had a qa aa ach d, 5 38 ca h hd had a hgh x ha h gh d ad 3 ca h wa. A a dy h x ddc g ca 1 c hck gg ha h x ca wh a ha ac aa a hck 5 c. Th d aa cv ad-ad d h 6 a a hw h cvav ca Fg 11 h d kd aa. Th cvav d da d h y ga 17, 3 ad 4 h c,, ad wa aa wh h ax d 83, 15 ad 2 cvy. I a x ca ha vd av yca d h, h a d a w a ad Fg 12. Th da d h ca a 4

14 6, 11 ad 3 h c,, ad wa aa wh h axa a 3, 57, ad 15 cvy. a S 15 a S 15 a S Aa D Aa D Aa D.2.1. B B B Fg 11 Ecv aa d d ad c,, ad ad wa h cvav x ca a S 15 a S 15 a S Aa D Aa D Aa D Fg 12 Ecv aa d d ad c,, ad ad wa a yca x ca ak a a Th a aa ga a hw a wd ag h a ada chaacc c h w cd ca hy had vad gaa. Tw h y (CK ad LD) w cd ca hy a av h chaacc h ajy ga. Ta 3 az h aj ada chaacc h 14 a. Th h a h a a. Th x w a a h a a ah y. 41

15 Ta 3: ada ga a Sa Sac d a Svh -1 (µ h -1 ) 222 R aa Bq -2 h -1 (C -2 h -1 ) 222 R aa % 222 R gy * Bq kg -1 (C/g) 22 R gy * Bq kg -1 (C/g) FS9 16 (16) 125 (32) 2 17 (46) 3 (1) FS8 2 (2) 12 (3) (51) 3 (8) FSMK 16 (16) 6 (155) (43) 27 (7) JBMK 14 (14) 16 (42) (157) 9 (24) JBSR 6 (6) 17 (44) 5 (135) 5 (14) JDJF 4 (4) 6 (15) 7 25 (68) 5 (14) G8 4 (4) 38 (96) 2 7 (19) 2 (5) CB8 2 (2) 5 (13) 8 2 (54) 2 (5) JB8A 16 (16) 35 (9) 8 14 (38) 2 (5) JB8 () 3 (76) 11 8 (22) 2 (5) SUMK 6 (6) 6 (16) (4) 57 (15) LD8 4(4) 4 (11) 16 1 (3) (3) CK8 3(3) 6 (16) 25 6 (2) 7 (2) CK88 3(3).5 (1.4) 3 7 (2) 7 (2) C a ; aa ~.1 2 (1 2 ) x 2 3 c hck Avag h hd ad hd d Saa a h a a * Ra cca a, qa a, ad a h c Ta 4 hw h ad x h a a ad y d aa y. Wh a hgh dc h ca h a ca d ah a h cdg, h daa a h dc x w h d h d (Kaa, 29A). Bh h CB a ad h FS a (a a) hw ayca aa ha h a gca dc aa hd h gh d h a. Th JB (Jaaa Bdax) a a h a y d a. Ev hgh hy a h d h ack d, h aa w h d d JB8 qva h hd d h ca JBMK. 42

16 Ta 4 Caav ad x ( C -2 h -1 ) h d cd a g a vay a y. Ec +CRM 5L Bw +CRM 3L Bw +EIC EIC Rad Fx M Mhd Sa/ac CK8 hd gh a ac * 16 * 2 * CB8 hd 9 7 gh a ac FS8 hd gh a ac FSMK hd gh a ac JB8 hd a ac JBMK hd a ac * Th c hadd gy a avag h w c av. -ak ad ad ad aaa h Oy h- ad a a cy avaa h c 35 Mdw h. T da, h ad aa ga 11 h hav ad. Th avag aa a wa C -2 h -1 (4 Bq -2 h -1 ), h da wa 5 C -2 h -1 (2 Bq -2 h -1 )ad h ax wa 9 C -2 h -1 (35 Bq -2 h -1 ). Ta 5 Sh- avag a ad cca h wh dcav ga. Lca Avag Rad (C/L) Mda Rad (C/L) R wh ga R ga Ba

17 DISCUSSIO Th ca c h wk wa d acca hd dyg ga aa ha had h a ga ada d av cdd v. I gh h gca vaa ad ca acad wh h ac ha c ORM d a dvda, cvav ca h c ga aa ha dcd cv d ha 25 5 y -1 w dd accay a (HS 29). Th chc hd a acca aa ga ad d h d h xa gaa ad a ad gy x ahway. Th, h ada c ga a cvd dg ay ad ga ha ca d va d cc d. Exa gaa d F xa gaa ada, cadda a acca ga h adcd cca d h ga aa. Th gaa d d dg a aa ca cacad h ad adcd cca d h aa ad a aa c - a d ha caca h d d h vcy h aa. Th Ea C (EC, 1999) ak h aach y g h avag cca h ORM a a aa cc a d dx. Th dx acay h dcd aa cv d ( Sv) a dvda h c a ccd h ORM aa. F h caddg h aa, a dx 2 (cdg a d 3 y -1 ) d gg a dad d a h aca gy ad h aa. Fg 12, whch hw h d h dx cacad h aa CSG a hw ha a gca xcd 2 ad h ax dx av 9. O c, dcav ga aa w hav w d ca hy vv aa ha c ac cag, ad h ca c, hav d x gy. A vga g h aach h ga ad h wk gg Gaa D Idx Fg 12: Gaa d dx cacad ORM cca ad 3 a. (Th d dx cd h aa d ( Sv) d a hyhca x ca.) 44

18 Ah cadda a acca xa d ga h ad gaa d a d h a ac. Th a ca d wh a aa d d d dvd aa vaa a h d d a ga a. Fg 9 (av) a ha h d a ady away h a vcay ad hzay, cay h a h a. Tw a d a d hav dd a. Th aach cy g vd a hd a. ay gg ha h 3 ga a aa ad wd xcd cdd d wh d a a c a g. Oy w a had h ha wd xcdd h wh d a a dk, 14 ga a wd hav xcdd h a d ad wa had cad wh ha ga. Hwv, c ad wa a ay hd h hck a, h aa h wd hav xcdd h cda. B, had h cd ga a d Ta 3 d a ac, w aa wd hav xcdd h aa ad 4 wd hav xcdd h wa. Ia ad-ad d F h a d ad gy, h a c cv d ca a h d h ag dcd av, ghy 4 5 y -1. Tha ag cd h d xcd h w accay-achva d ad cca, h qva d a cca. O h 6 a ha w ad ad aa, 8 wd xcd h c va c aa, 25 aa, ad 34 wa aa. O h a ga a, 2, 5 ad 6 h 14 wd xcd h c v h d aa cvy. F a a cv, wd h h xa d ga cd d h a d a w. Uay, h ac d a adcd cca w gh cad wh h ad aa a v a a va ga a d. Th ad ha ca a a dd h a cd (ad) c ad h ac ad gad h a ha ca ca. Th a chaacc dd h ca h ad ag a h a ad h hyca y acg h a. Th chaacc ca ad ag dc ad aa ac y--y ad ca a--a wh h a y. Fg 13 a y aa vaa wh h ad ag a a a h ac ccad a v a. Th gaa h, away, cdd ad x gh. 45

19 Fg 13: Sa h aza; gy a Jaaa Bdax, ad yw a agaa Gd gh Gaa d a a ad x ga Fg 14 hw h ac gaa d a ad ad x a h ~45 ad h 6 a ad aa. Rca ha h a w -cd ca hy w hgh a ad gy, a gaa d a. Th ag hw h ax ad x ha wd dc a d a h cdd v a c aca cvav ca (~ 6 Bq -2 h C -2 h -1 )). Bd h ca, ac d a wd ak a gd dagc ac a y xa hgh aa ad w gaa d a w a w aa ad hgh gaa d a vd. F xa y ch a gaa d a gg 3 µ h -1 h h, 8 aa wd cad ay a a ad 36 wd cad ay a a Rad Fx Bq/^2-h Gaa d a c/h Fg 14 Rad x ad ad aa a v 4 6 a ad 14 a 46

20 Oh ca gaa d ad ad x, ch a h h gaa d v a avag aa hw Fg 15, gg ha ac gaa d a a adqa ad x ga. F c aca (ag ), a gaa d a gg 3 µ h -1, ca 2 a v ad 3 a gav h a 6. Th gg wd hav wd ~ µ h -1 a a gav. B ha gg wd ca a 25 a ay cad a a. Th a xacad wh xv ga aca a aayzd. Th yw ad v Fg 15 hw h x ha wd ca ad-ad d xcd h cda h ca, ad wa x ca. Avag ad R aa Bq/^ Hgh ad Da c/h Fg 15 Sa avag ad x ad ax ac gaa d 6 a. Th ag, yw, ad v hw h a c,, ad wa aca. Fg 8 ( c av) gg a h a ac gaa d a a a gd ga ad x; h a ad gy c h gaa d ha a gca w ad hgh aca c h ac gaa d a. Ra ad gy cca a a ad x ga I ha ggd ha a ad gy c h a wd cad wh ad aa. Advacd a gaa c k h Caa I1k, ca d h adcd c ORM aa a a wh vad cca wh a w. Th a ada ad q y d chca k c hy a caad hy a a aa aav ag ca cad h x a acy ag a ad aa. 47

21 Fg 16 hw h ah w h a avag a ad gy ad h ad x ag wh x va d-x ca. Wh h ca w ad x ad a ad gy ha ac d a, h a gh vaa q adda a y. F c aca, a wh a ad cca w a 3 Bq kg -1 wd a cy h a c cagy. Fg 7 () hw ha h CSG-vy a (75%) h cd. Th y h ga ca xdd wh ad aa a a ad a a a aca whch hav x a h. Th gg ca wd wh aa ac ha ady ad ca h aa ac ky a ha h 5% d g h a. Avag ad R aa Bq/^ Avag ad a R Bq/kg Fg 16 Sa avag ad x ad avag a ad gy 6 a. Th ag, yw, ad v hw h a c,, ad wa aca. Th ad gy gg v g cca, ad wa x ca wd 15 ad 1 Bq kg -1 cvy. Cay ay dd ac aca q ad aa a. acca -ak cg c Th a x va, a ad gy cca ad h vaa ca cd a caca ch c xg ad w vy a h cg, d aca v. Th ky a a h adcd c a a y ad v a h qad aa ak d c h d. A hca daaa ad gy cca ad ad aa ac ay wd aw c ad cv cg vy. Th wh cy w a ad gy (xac va wd dd h h h 48

22 ad aa a) ca ad qy ad vy. Th a wd hav a gg va h ac gaa d whch, xcdd, cd dca ha a ad gy wa av h gg v aa. Wh h d gg va xcdd, h a ad gy d ad, ad h ad a gy xcd h aa gg v, ad aa a d ad h a k vy. I h wk, whch cd ay a d a c, h ad x wa ad h a ach y ha had a ad gy ga ha 3 Bq kg -1. Th a hd ah h avag va ad vaa h aa ac ach y. Th chaacc w d caca a gg va h a ad gy a ha y. I h w a xcdd h gg va, h h ad x had ad ha a wd jcd c h vy. Th -ak cg c w g d y Cd Sg Ga h ay h c vy. COCLUSIOS M dcav ga ca accay w ada x h aa. Hwv, hd d ag ca aa a vg ac wh w va ca hy ga gh ad ca d xc h cdd y ada c gaza ca ada c. Th y ha ay ca xcv a ada d ca dd ad gaa a a. I aca, h ac gaa d a whch ay ad wh vy cv cg a ay ad ay d h a. Hwv, a y cagy hcad cg a ad gg va cd wh xv aay h ad gag a ad adcd c y ca cvy h ay dcav ga ad avaa h c. ACKOWLEDGMETS I wh hak Jh Mak, d Cd Sg Ga Cay, h g ca wh h jc ad J Fch, ad Jy Mddad h Egg ad Qay Eq Da h aac ad had wk. Thak D. a Kaa, RAD ELEC Ic., h cva ad ad aa q ad. S -ak a q ad w gy dad y B.V. Avaz, AChk Ic. Thak A Gha, Th Ca Sh, Lda Kcad, Ida Hyg Svc, J Bg ad Mk Sa Ga Svc ga a. Da Faa ad Davd Ha ad a aa a ad gaa ada dg. 49

23 REFERECES Bdhad WB. Mag ad ad h aa cc ad ga wh c ad ad EERM. cdg h Aca Aca Rad Sc ad Tchg 28 Iaa Sy La Vga V, S 14-17, 28. Eva Hah ad Egg Ic. Ag x ada ad ad ga c. 28 h:// accd 8/7/29 EA aa C Eva A Ex Fac Hadk (1997 Fa R) avaa a h://c.a.gv/ca/c/cday.c?dd=12464; accd 8/7/29. Ea C, Dca-Ga, Ev, ca Say ad Cv c Radgca c c ccg h aa adacvy dg aa. Rada c 112, 8 (1999) Hah hyc Scy. IOIZIG RADIATIO-SAFETY STADARDS FOR THE GEERAL UBLIC, h:// accd 5 Ag 29 K ME, G J Eaa ga c. cdg h Aca Aca Rad Sc ad Tchg 25 Iaa Sy, Sa Dg CA ( 25) K M.E, Ha D.K, Az H.D. Eaa ad hhd ga. Hah hyc: 6: (29) Kaa, Dy J.C, Ray R.W ad S L.R. A acca E-ERM Sy d ad a. Hah hyc (199) Kaa, S LR, Vkvky. Rad caa g IST ad aa adad: ady w hd. Rada c Dy 113:7-74:25 Kaa ad F S Rad xhaa a dg aa g c cha acca Hah hyc 97: (29) Kaa S F Sck DJ. Rad x a ga ad cc ac. cdg h Aca Aca Rad Sc ad Tchg 29 Iaa Sy S. L MO. (29A) Sck DJ Uhd Cd Sg Ga Cay, achvd a h:// accd 8/7/29 5

24 Sck DJ. A ay vy h h U Mdw. Sxh Iaa Rad Sy, Kaa Cy M. S 26 Avaa a h:// Vkvk. IST 222 Rad adad. Ad Rada ad I. 64: ; 26 51