Water Quality Considerations Project Travois

Transcription

1 , : UCRL-ID Water Quality Considerations Project Travois = J B Knox July 16,1968 This is an informal report intended primarily for internal or limited external distribution The opinions and conclusions stated are those of the author and may or may not be those of the Laboratory Work performed under the auspices of the USDepartment of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-ENG-48 *,

2 ' : hw-ence Radiation Jaboratory K-Division, T-16 ': L-42 J u l y 16, m i 6 -docme -- -_ No 3=bf To: Distribution J B I@ox SUBJXCT: Water Q u a l i t y Considerations - Project Travois The t e c h n i c a l concept for Project Travois (6/1/68) contains one simple a n a l y s i s of t h e p o t e n t i a l hazard of contaminating t h e Arrowrock Reservoir on t h e Boise River (some 16 miles from t h e Travois S i t e ), with some of xhe radionuclides produced This previous a n a l y s i s assumes homogeneous and prompt mixing of a l l t h e tritium and tungsten isotopes, and \?85, i n tliis r e s e r v o i r with t h e result t h a t CT = 20 I4PC (w) and ~ ~ $ 8=1 5 "PCw, Clr+05= 40 MPCw This simple a n a l y s i s is physi- c a l l y u n r e a l i s t i c since t h e r e is, as we shall see, no way of t r a n s p o r t i n g a l l of t h e s e radionuclides t o t h e reservoir, promptly W e shall i n t h i s paper reanalyze t h e contamination problem i n such a way that we d e f i n e t h e t y p e of s i t e geology nnd hydrology information t h a t must be developed (a) T r i t i u m : Assumptions: 1 The 40 kt Plotishare ExcavatioE Explosive'nrakes 800 k i l o c u r i e s of tritium (Ref u n c l a s s i f i e d source statement) 2 "Tne produced tritium i s i n t h e form of HM and uniformily mixed i n t h e 7 3 L X 6 10 cu yards of rubble The proposed depth of b u r i a l i s 200

3 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its usc would not infringe privately owned rights Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, Iccommendrtion or favoring by the United States Government or any agency thereof The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof

4 DISCLAIMER Portions of this document may be illegible in electronic image products Images are produced from the best available original document

5 -Problem I: -?we 2 The T r i t i u h i n the Retru'c Step 1 If t h e proposed r e t a r c could be completely f i l i e d with water t h e tritium concentration i n t h e waterf i l l e d voids i s 6 CT ( 0 ) = 8 >: 10 Ci/Vr Q where Vr = t h e volume of rubble = 7 X 106 (92) 3 x 106 cc Q = p o r o s i t y (m25) Hence, ct ( 0 ) = -54 pci/cc or CT ( 0 ) = 540 MPCu where Physically, CO(T) = 540 MPCw (T) c o n s t i t u t e s t h e dsymptotic value o f the concentration f o r a pulse of clean water precolating i n t o t h e r e t a r c Step 2 The maximum 24 hour r a i n f a l l ( i n 50 years of record) I n t h e area is 3 inches The volume of r a i n vater f a l l i n g within t h e 515 foot-radius r e t a r c i s V = f i (16000)2 x 10 cc = 8 x 109 cc = 8000 m3 P This volume of r a i n water is -4/1000 of t h e pore space i n t h e r e t a r c, Questlon: How fast does t h i s pulse of t r i t i a t e d trztcr nave out of t h e r e t a r c? Step 3 IIydrology experience gives an estimated upper value for sub-surface, downhill flow of ground water i n f i s s u r e s may be of the order of loo'/day o r 3000 cnl/day ( B i l l Schell, p r i v a t e communication) From c

6 Muskat (p 425 Flow i n porous media), we can calcul a t e t h e corresponding f r a c t u r e width as O3 cm The d a i l y volume flow f o r one fissure connecting r e t a r c t o the h i l l s i d e (See Figure 1) i s 03 (3000) L cc where L i s t h e lateral length of t h e fissure on t h e h i l l s i d e (16000 cm); it is reasonable t o assume about ten such f i s s u r e s since t h e p o s t u l a t e d pulse of r a i n water f i l l s only 4/1000 of t h e r e t a r c ' s pore space Under these conditions t h e volume of w a t e r seeping from t h e r e t a r c t o t h e h i l l s i d e (and hence t o the 3 stream) i s (10)x 1500 x 10 CC The d a i l y tritium burden" given t o t h e stream under t h e s e If conditions i s 540 (MPCw) 1500 Step X lo3 X 10 4 'If the d i l u t i n g power of the stream at l o w flow i s s u f f i c i e n t, then no problem e x i s t s i n regard t o tritium from the r e t a r c under t h e assumed conditions Such i s t h e case if t h e "daily tritium burden'' divided by t h e minimum observed d a i l y f l o w on t h e Boise River (124 c f s = 29 X smaller than 1 10" cc/day) i s much 540 TOL X 1500 X lo3 X 1O/day 29 x' ' 0 1 X cc/day = -028 << 10 Hence, we conclude for the assumed system t h a t tritium originating i n t h e r e t a r c and p e r c o l a t i n g t o the stream can be d i l u t e d s u f f i c i e n t l y by the low flow such that Clq (T) a n entry t o t h e Arrowrock Reservoir i s less t h a n X P C This seepage source, of t h e form discussed above, could l a s t 8000/15 days Th& current uncertainity i n the 028 EKP i s large i n 1

7 Page 4 view of t h e absence of s i t e geologic data on f r a c t u r e width s i e c t r a and t h e i r hydrologic connection, Discussion: I n t h i s regard,-the most s e n s i t i v e parameter i n the abuve analysis is, i n my judgment, t h e f r a c t u r e width i n t h a t t h e steady-state flow through a f r a c t u r e i s proportional t o t h e cube of t h e f r a c t u r e width Pre-shot as vel1 as post-shot f r a c t u r e s connecting t h e r e t a r c t o t h e h i l l s i d e ( o r stream) a r e equally important Measurements of t h e pre-shot f r a c t u r e frequency and width at t h e Travois s i t e do not exist a t t h i s t i m e, b u t are now planned by XCG This organization has measured pre- and post-shot f r a c t u r e s a t Danny Boy (Paul Fisher, p r i v a t e cornmication, following r e s u l t s : 1968) with the 7 HOIX coimra P?X-SHOT DA 2 edge of c r a t e r 12/64" = -5 crn 10/64" = 5 cm DA 5 two c r a t e r r a d i i POST- SHOT 14/64 I' 13/64" These above f r a c t u r e widths measured on Buckboard Mesa a r e > 10 times that assumed above Should such pre-shot f r a c t u r e s be shovn t o e x i s t a t t h e Travois site, t h e above analysis would show q u a l i t y problem i n t h e Boise River 8 tritium w a t e r I n t h i s event rn operational solution would be required, such a s p l a s t i c sheeting covering t h e retarc (and e j e c t a ) L during p r e c i p i t a t i o n (average annual -13 o r 14 inches) for t h e post-shot operational phase Problem 11: T r i t i u m i n E j e c t a Outside of Retarc The surface a r e a of the e a r t h covered with e j e c t a from t h e detonation w i l l be of t h e order of three times t h e r a d i u s of t h e r e t a r c (16000 cm) The volume of r a i n water falling on t h i s e j e c t a is (from Problem I) -80,000 m3 for conditions of extreme

8 The "tritium burden" delivered t o t h e stream daily rainfall i n sheet runoff of t h i s extreme day i s 540 X 80,000 x 106 (TOL) cc/day The tritium concentration i n the stream after d i l u t i o n of t h e above tritium burden is given as follows as a function of average d a i l y flow: Observed d a i l y flow Tritium Concentration i n t h e stream ( a f t e r mixing) Comments 124 c f s 135!rQL min i n 50 years average max in 50 years TOL 12 TOL The CT i n t h e stream r e s u l t i n g from leaching of HIXI from surface rubble suggests t h a t i n t h e absence of surface runoff diversion works near t h e r e t a r c, there i s a r e a l p o s s i b i l i t y of a p u l s e of tritium i n excess of MPC s t a r t i n g downstream Travois p r o j e c t, engineers can, I believe, devise a scheme f o r r e t a i n i n g i n storage 80,000 m3 of t r i t i a t e d water f o r controlled r e l e a s e o r disposal If aggregate i s t o be washed p r i o r t o use, such a provision f o r storage would be required, anyway Oar consideration of Problems I and I1 i l l u s t r a t e s two tp +' p r i n c i p l e s of water q u a l i t y control grspw e L pchlkt%iy de L$, -c-&z~, - d i l u t i o n ard i s o l a t i o n Winen t h e waterasolution:, can be developed The discussion of these problems, hopefully, i l l u s t r a t e s t h i s approach It a l s o i l l u s t r a t e s t h e need t o use s i t e hydrology and f r a c t u r e s t u d i e s t o evaluate roughly, t h e problems of water quality (b) Radionuclides other than tritium: It i s p e r t i n e n t t o examine some other radionuciides i n t h e same context of ProSlem I (leaching of r e t a r c material) and Problem I1 (leaching of e j e c t a and sheet-runoff t o t n e strem) we consider "?L and whose For t h i s purpose rodqction on Travois have been 6 4%K I O b C ; estimated to be 26 x 10 CiA respectively (Howard Tewes, p r i v a t e communication, 1968) Ion exchange e f f e c t s will be estimated as +' we assume 1/(1 i- K&D), the f r a c t i o n of t h e nuclide appears L

9 ~ ~ - Page 6 - i n e q u i l i b r a t e d solute, i s equal t o o r smaller than t h a t f o r Sr i n -- t h e same ion exchange material (crushed g r a n i t e ) ( B i l l S c h e l l and H Tewes, p r i v a t e communication, 1968) 26) estimated 1/(1 K ) f o r f i o x (1963, UCRL-7350, Srgo i n g r a n i t e chimney material as dp If t h e W-nuclides a r e homogeneously mixed i n chimney rubble p 1/25 and e j e c t a, then we may generate t h e following estimates (wci/cc/dry) Conc i n solution with ion exchange The a n a l y s i s f o r W-nuclides is now p a r a l l e l t o that given a b w e for tritium result t h a t :, Problem I Problem I1 (I) 50 year low d a i l y (11) Diversion of sheet runoff from max storm i s required flow provides sufficient dilution w185 '! Comments: Since t h e overland sheet runoff i s presumably c o n t r o l l a b l e through diversion, storage, and planned release ( o r d i s p o s a l ), t h e c o n t r o l l i n g factor i s t h e sub-surface flow containing tritium, For t h e postulated cases analyzed, t h i s source of p o t e n t i a l water contamination w a s shown t o be acceptable because of stream d i l u t i o n However, f r a c t u r e premeability i s proportional t o t h e cube of the f r a c t u r e width (Phskat, p 425); hence, we a r e no% c e r t a i n t h a t explosion produced fissures a t g r e a t e r than two c r a t e r radii a r e < - O3 cm, as assumed i n the a n a l y s i s I s t r o n g l y recommend that : (a) Fracture widths be measured a t 1, 2, 3, o r more c r a t e r r a d i i and pre-shot a t Project Excavator and a t the proposed Travois s i t e as soon as possible A

10 (b) -A s u i t a b l e t r a c e r study for the r e t a r c s of P r o j e c t Excavator be designed t o develop d a t a i n seepage rates and hence on average connected f r a c t u r e widths (c) W e request t h a t t h e NVOO contxactor (IDJS) perform the s u i t a b l e ion exchange measurements on and &85 whose d i s t r i b u t i o n c o e f f i c i e n t is reported t o be v e r y ph dependent Distribution : l/14 A Gibson, T A Higgins, G H Knox, J B Korver, 3 A Hordyke, M E Shore, B W Tewes, H A Toman, J Werth, G C, HoLxes, R S Hughes, 13 C 2/14 A 3/14 A 4/14 A 5/14 A 6/14 A 7/14 A 8/14 A 9/lk A A 11/14 A 32/14 A 1344/14 A Stead, F (USGS) File c

11 - 1! 9 c \FI =&M---maX c - - Schematic Profile: Figure 1 i Seepage paths Travois pulse f r stc (4/1000 of rets