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Assessment of the Potential for Raclionuclicle Migration from a Nuclear Explosion Cavity 11 INTRODUCTION DARLEANE C. HOFFMAN and WILLIAM R. DANIELS Los Alamos National Laboratory A field study of the distribution of radionuclides around an underground nuclear explosion cavity was initiated in 1974, about 9 yr after detonation of the nuclear test. This study is part of the Radionuclide Migration (RNM) Project, a broad investigation to determine the rates of migration underground in various media at the Nevada Test Site (NTS) and the potential for movement both on and off the NTS of radioactivity from underground nuclear explosions. It was also envisaged that the study might provide data applicable to the underground dis- posal of radioactive waste. This ongoing project is sponsored by the Nevada Operations Office of the Department of Energy with the participation of the Los Alamos National Laboratory, the Lawrence Livermore National Laboratory, the U.S. Geological Survey, the Desert Research Institute, and appropriate support organizations. The site of the 0. 75-kiloton nuclear test Cambric, which was detonated beneath the water table in tuffaceous alluvium, was chosen for initial studies. It was anticipated that eventually tests in other geologic media would be examined. Cambric was chosen for a number of reasons. The Cambric explosion cavity is within the NTS Area 5 water-supply aquifer, and there was particular interest in possible contamination of water supplies. It was predicted that sufficient time had elapsed so that the cavity and chimney had filled with groundwater to the preshot static water level, 73 m above the detonation point. If so, radionuclides might be present in the water and constitute a potential source for migration. The Cambric detonation point 139 is only 294 m below ground surface, and thus the re-entry drilling and sampling operations would be less difficult and expensive than for some of the more deeply buried tests. The site in Frenchman Flat is far enough from the areas of active nuclear testing so that damage or interruption of the re-entry and sampling operations from those activities would be un- likely. Sufficient tritium (3H or Ti was present to provide an easily measurable tracer for water from the cavity region. The postshot debris also contained plutonium, uranium, and fission products whose concentrations in the rubble and groundwater from the cavity and chimney regions could be measured and compared. A summary of the intensity of the radionuclide source term at the time of re-entry is given in Table 11.1. The small yield was expected to have had little effect on the local hy- drology. Further, it was judged that the alluvium constituted a good medium for hydrologic studies because it was more permeable than tuff and did not have large fissures or cracks through which the water might selectively flow. The Cambric cavity region was re-entered, and a well (RNM- 1) was completed to a depth of 370 m. Samples were taken to determine the radionuclide distribution between the solid ma- terial and water at the time the experiment was started. Water was then pumped from a nearby satellite well (RNM-2S) to induce an artificial gradient sufficient to draw water from the Cambric cavity and provide an opportunity for the study of radionuclide migration under f~eld conditions. A schematic dia- gram of the placement of RNM-1 and RNM-2S is shown in Figure 11.1. Details of the early stages of the RNM Cambric experiment are given in Hoffman et al. (1977) and Hoffman (19791.
140 TABLE 11.1 Cambric Source Term 10 Yr after Detonation ° Half-Life Activity Nuclide (Yr) (Ci) 3H 12.3 3.4 x 104 8~Kr 10.7 4.4 90Sr 29 34 i06Ru 1.0 2.8 ~ lamb 2.8 3.2 ~ tOO 37Cs 30 99 44ce 0.78 0.4 l47Pm 2.6 33 an luau 5.0 6.4 go CAM BRIC RE -E NTRY Three types of samples were recovered from the RNM-1 re- entry hole into the Cambric cavity: sidewall cores, pumped water, and water with contained gases. As drilling progressed, 67 sidewall core samples were taken from RNM-1 from 34 m below the surface to 50 m below the original detonation point (Figure 11.2~. One core from each depth was placed imme- diately in a nitrogen-flushed, gaslight, stainless-steel container for subsequent analyses of 85Kr, [IT, and HTO and for gamma- spectral analyses. Other core samples were sealed in watertight plastic bags for later gamma-spectral and radiochemical anal- yses to determine the concentrations of the various radio- nuclides present. The cores were also examined to determine the Ethology of the medium at different depths. Solid samples and water removed from the sidewall cores from the lower cavity region were analyzed radiochemically for 90Sr, i37Cs, and 239Pu, and effective distribution coefficients (ratio of the con- centration in or on the solid to the concentration in the aqueous S ~ RNM- 2S ~~ /~ ~RNM-i N PUMP 316 m 340 m _~221 m GRAVEL PACK / WATER LEVEL BELOW 210 m / 91m i294mWP / CAVITY ( RADIUS 10.9 m) . }-PERFOR- / ATIONS / 370 m T.D. FIGURE 11.1 Schematic of RNM-1 and RNM-2S. o LLI CD 200 f DARLEANE C. HOFFMAN and WILLIAM R. DANIELS > 300 LLJ 400 W.P. i~-C5,i i' J~'i ~ m Em- I WATER FIGURE 11.2 Locations of sidewall core samples taken from RNM- 1 (triangles). :Roman numerals indicate locations of isolated water sam- pling zones. The detonation point is indicated by W.P. phase) were determined (Table 11.2~. These effective distri- bution coefficients are a measure of both retention in the fused material and sorption. The radionuclides were found to be almost entirely incorporated in or on the solid material. After sidewall core sampling had been completed and the hole had been cleaned, casing was installed with appropriately placed, inflatable, external packers. The packers were used to minimize external water movement in the annular space be- tween the casing and the wall. Beginning at the bottom, the water in five zones was sampled successively by isolating the TABLE 11.2 Effective Distribution Coefficients in the Lower Cavity Region Distribution Coefficient (mL1g) 9"Sr ~ 37Cs 239pu 104 >104 108
Radionuclide Migration from a Nuclear Explosion Cavity zones with internal packers and perforating the casing (Figure 11.3~. Gastight water samples were taken at depth, and addi- tional water samples were removed to the surface by a sub- mersible pump. Representative activity levels of the radio- nuclides detected in water from each zone are given in Table 11.3. Ten years after the test most of the radioactivity and the highest concentrations of all radionuclides were still found in the region of the original explosion cavity. No activity was found 50 m below the cavity. Measurements of HT and HTO removed from the cores and gaslight water samples showed that more than 99.9 percent of the tritium was present as HTO. Although some 85Kr and tritium were found in the collapsed zone above r 200 220 _ 240 260 _ cx: At 280 320 340 380 ~ U-5\ l Covi ty Cemented annulus 1 ~ /:RNM-1 Al; r Center I i ne 2.4-crT Casi rig Rewater tab ~ e at 221.0 Casing and hol e diameter drawn using expanded scaleofl ;nch=50cm ,, Lynes dr; I labl e packer Lynes external casing packer In open hole 12 1~7/ /~ Total Depth l 160 140 120 100 80 60 40 HORIZONTAL DISTANCE SOUTH OF SURFACE SITE OF RNM-1 (m) 141 the explosion region, they were concentrated in the cavity region. The measured 85Kr-to-tritium ratios for water from the explosion cavity zone were consistent with the relative amounts resulting from the Cambric test; the 85Kr seemed to be dis- solved in the water. No 85Kr was observed in water or solid material from cores taken above the water table. Water from the region of highest radioactivity at the bottom of the cavity contained only tritium and 90Sr at levels higher than the rec- ommended concentration guides (CG) for water in uncontrolled areas (Standards for Radiation Protection, 1977; National In- terim Primary Drinking Water Regulations, 1978~. By comparing the measured ratio of each nuclide detected FIGURE 11.3 Construction details of RNM- 1 in and near the lower part of the Cambric chimney. Roman numerals indicate isolated water sampling zones. The original emplace- ment hole was designated U-Se.
142 DARLEANE C. HOFFMAN and WILLIAM R. DANIELS TABLE 11.3 Representative Activity Levels in Cambric Water Samples 10 Yr after Detonation Zone Below cavity Lower cavity Upper cavity Chimney Adjacent to chimney CGc Tritium Activity Level (~Ci/mL) baa 6.1 3.8 0.084 0.028 2 X 10-S Activity Level (dpm/mL) 83Kr 90Sr l06pu bg 800 1200 70 20 bg 8 5 5 0.2 0.018 125Sb bg 11 ndb nd 22.2 bg 5 2 nd nd 222 137Cs bg 1.6 1.4 0.8 0.2 44.4 239pu bg ~0.003 ~0.003 nd nd 11.1 abg, no activity detectable above background levels. tend, not detected. CCG is the recommended (Standards for Radiation Protection, 1977; National Interim Drinking Water Regulations, 1978) concentration guide applicable to water in uncontrolled areas. Values for tritium and 90Sr in public drinking water standards established in National Interim Drinking Water Regulations (1978). in the water to the tritium in the water with the calculated ratio for the Cambric source term, an e~ective overall retention factor, E,J, for each nuclide (ratio of the total activity in or on the solid to the total activity in the aqueous phase) was esti- mated. (This calculation assumes that all the radionuclides had been retained below the water table and that the fraction of a nuclide not in the water was in the solid.) E _ (AX/AT)CambrIC(AXIAT)Wa~er = (AX Cambric) (AT water) _ (AX/AT)Water (AX water) (AT Cambric) Substituting T water _ O. 999 ~ T Cambric AX Cambric Ed= - 1. X water Then or Ed = X solid ~ K ~gsolid X water CCwater wt. % water K ~ E d d 100wt. % water where Kd is the distribution coefficient. The nuclides 90Sr, i06Ru, i25Sb, 137CS' ~47Pm, and 239Pu were all found to have high retention factors, indicating that they are either retained in the fused debris, highly sorbed on the solid material, or both (Table 11.47. TABLE 11.4 Retention Factors from Cambric Water Samples SATE LLITE WE LL The satellite well RNM-2S was located 91 m from the Cambric explosion cavity. Pumping was begun in October 1975 at a rate of about 1 m3/min; in October 1977 the rate was increased to about 2.3 m3/min. Significant amounts of tritiated water, sig- naling arrival of water from the Cambric cavity region, were f~nally detected after a total of about 1.44 million m3 of water had been pumped from the satellite well. After almost 6 yr of pumping, the tritium concentration in the pumped water ap- pears to have reached a maximum, as shown in Figure 11.4. Discontinuities in the plot correspond to periods during which the pump was not operating. Since the observation of tritium in water from the satellite well, samples with contained gases have been taken by pump- ing from RNM-2S and from RNM-1. Results for such samples from the satellite well indicate the presence of 85Kr (Figure 11.5), a gas that apparently was retained in the water during transit. The 85Kr/tritium atom ratios are shown in Figure 11.6. It should be noted that these are relatively constant at a value of approximately 0.4 x 10-4, considerably lower than that of 1.22 x 10-4 calculated for Cambric. So far the reason for this is not known; however, this result may very well be related to events occurring at RNM-1. The pump and packers in RNM- 1 were left in a configuration such that pumping removes water from Zones IV and V (Figure 11.3), wI}ich are just above the cavity region; most of the water production is believed to be from Zone IV. Data for water pumped from RNM-1 are pre- Zone 90Sr l06Ru 12ssb 137Cs l47Pm 239pu Below cavity baa bg bg bg bg bg Lower cavity 2.1 x 103 1.0 x 102 2.9 x 1o2 2.5 x 104 >106 >3.2 x 107 Upper cavity 1.6 x 103 1.9 x 102 3.6 x 102 1.8 x 104 nd >1.9 x 10' Chimney 3.9 x 10~ ndb nd 6.6 x 102 nd nd Adjacent to chimney 3.1 x 102 nd nd 1.1 x 103 nd nd abg, no activity detectable above background levels. tend, not detected.
Radionuclide Migration from a Nuclear Explosion Cavity 7500 - 7000 - 6500 - 6000 - 5500- 5000- 450C 400C 350C 300C 250C 200C 150C lOOC 50C ~ f 1 ~ F _~ ,~x OF Vet O ~1 1 1 1 1 1 1 1 1 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Vo l ume Pumped ~ 106 m3) FIGURE 11.4 Tritium concentration in water from RNM-2S, cor- rected to Cambric zero time. 1.0- - 0.8 - 0.6 - _' 0.4- x x Y x x . x x x xx x x x x x 0.2 - .. x x x x x x x x x x - 1 X x 1 ~ ~ 1 1 1 1 1 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Vo I ume Pumped ( 106 m3) FIGURE 11.5 8~Kr concentration in water from RNM-2S, corrected to Cambric zero time. TABLE 11.5 Tritium and 85Kr Activity Levelsa in RNM-1 Gastight Water Samples 143 ~ n - _ . _ 2.5- x 2.0 - ° 1.5- ~_ ._ A 0.5- 1.0 - x x x x x xx ^ ~ xx x x >( 0.0- 1 1 1 1 1 1 1.5 2 2.5 3 3.5 4 4.5 5 Vo I ume Pumped ( 106 m3) FIGURE 11.6 85Kr/T atom ratios for water from RNM-2S. The cal- culated value for Cambric is 1.22 x 10- i. 6 sensed in Table 11.5. The concentrations of tritium and 85Kr in water from RNM-1 have decreased by more than a factor of 100, presumably as a result of pumping at the satellite well; however, the 85Kr concentration is apparently decreasing more slowly than the tritium concentration. The 85Kr/tritium ratios obtained for samples collected from RNM-1 since pumping began at the satellite well are consistently greater than the calculated ratio. More than a dozen 55-gallon (0.21-m3) water samples, taken at intervals from RNM-2S since the first observation of tritium, have been reduced to solid residues by evaporation, and the gamma-ray spectra of these residues have been measured. With the possible exception of a very small amount of i06Ru con- centration <1 percent of that produced in Cambric (Coles and Ramspott, 1982) no gamma-emitting nuclides have been identified in these samples. Radiochemical analyses of other water samples for the beta-emitting nuclide 90Sr have also given negative results. Volume of Water T OK 8~KrlT Entry Date from RNM-2S (m3)b (nCi/mL) (dpm/mL) (atom ration Original-Zone IV 8/8/75 0 150 70 1.8 x 10-4 Original-Zone V 8/14/75 0 38 13 1.3 x 10-4 Re-entry Id 10/4/77 1.17 x 106 3.2 75 9.4 x 10-3 Re-entry II~ 11/30/77 1.34 x 106 2.0 6 1.3 x 10-3 Re-entry III~ 9/4/79 3.50 x 106 0.26 0.57 8.8 x 10-4 aAll activity levels corrected to Cambric zero time. Volume of water removed from RNM-2S by indicated date. The calculated 8~Kr/T atom ratio for Cambric is 1.22 x 1O-4. The packer between Zones IV and V was drilled out before pumping was started at RNM-2S. Water pumped for "re-entry" samples can enter from perforations in both Zones IV and V, but most of the water is believed to be from Zone IV.
144 After removal of more than 5.6 million m3 (over 1.5 billion gallons) of water from the satellite well, only tritium, which is present as HTO and chemically the same as the water, and 85Kr, which seems to be dissolved in the water, have been positively identified in water from RNM-2S. The arrival of tritium at the satellite well was compared (R. S. Rundberg, Los Alamos National Laboratory, personal com- munication, 1981) with the calculations of Sauty (1980) for an instantaneous tracer injection in a radial, converging flow field, similar to the Cambric experiment. The shape of the elusion curve depends on the Peclet number, which is inversely oro- portional to the dispersivity. The smaller the Peclet number the greater the dispersion, i.e., the broader and more skewed the elusion peak. In order to compare the experimental data with the calculation, dimensionless time, TR, and dimension- less concentration, CR, must be used. The dimensionless time is time T divided by the time when the maximum of the elusion peak occurs; the dimensionless concentration is the concen- tration at T divided by the maximum concentration. Since the maximum in the tritium concentration in water from RNM-2S is not yet well defined, a calculation was made based on the amount of tritium pumped from RNM-2S by July 6, 1981, specifically 24 percent of that produced in Cambric. Values for TR and CR were determined for the same date (5.60 x 106 m3 of water pumped) by locating the point on calculated curves of Sauty (1980) corresponding to elusion of 24 percent of the total tracer. The available calculated curves for several Peclet numbers were thus compared with the normalized ex- perimental data (Figure 11.7~. It appears that a calculated curve for a Peclet number between 3 and 10 (dispersivity between 30 and 10 m) would best fit the experimental data. This result can be compared with the data presented by Borg et al. (1976>, who reported longitudinal dispersivity values that were esti- mated by calibrating mathematical models for transport against observed transport. Values ranged from 11.6 to 91 m for a wide variety of lithologies. The dispersivity for a sand and gravel deposit, the Ethology probably most closely resembling the 1.0 - - 0.5 air \\\ O O- ~ ~ ~ ~ . I I I I I i I I I I I I o.o o.s 1.0 1.5 2.0 2.s D I MENS I ONLESS T I ME, Te FIGURE 11.7 Calculated elusion of tracer for instantaneous tracer injection in a radial converging flow field for Peclet numbers 3, 10, 30, and 1000 (from Sa,uty, 1980). Normalized data for tritium observed in RNM-2S water are shown by triangles for P = 3 and by circles for P= 10. DARLEANE C. HOFFMAN and WILLIAM R. DANIELS tuffaceous alluvium of the current experiment, was found to be 21.3 m. LABORATORY EXPERIMENTS Laboratory experiments have primarily involved measurement of the partition of various radionuclides of interest between groundwaters and crushed rock samples of various geologic media ("batch" studies). Some experiments involving the leach rates for the removal of various radionuclides from nuclear test debris have also been performed. In general, the rates for removal of a radionuclide from such debris were found by Wolisberg (1978) to be quite low (Table 11.6~. Results for the batch measurement of the sorption of a num- ber of radionuclides on tuffaceous alluvium and bentonite are given in Table 11.7. The sorption properties of tuffaceous al- luvium are comparable with those of bentonite, which is being considered for use as an engineered barrier because of its ex- cellent sorptive properties. Sorption-desorption equilibria are approached slowly, and results obtained for sorption measure- ments, where the tracer is initially present in the aqueous phase, and for Resorption measurements, where the tracer is initially present in the solid phase, frequently differ. We there- fore emphasize that "distribution coefficients" calculated from such data may represent nonequilibrium conditions. In addi- tion, it should be noted that such values for the laboratory experiments refer only to sorption phenomena and do not in- clude the effects of retention in fused debris as do the results given in Table 11.2. The "irreversible" sorption or much slower Resorption may be due to speciation changes, diffusion into minerals, crystallization reactions on solids, or nonionic sorp- tion of colloids or precipitates. These possibilities require fur- ther investigation. A comparison of the results from laboratory sorption exper- iments (Table 11.7) and calculated retention factors from Cam- bric water samples (Table 11.4) indicates that most of the ra- dioactivity from the explosion is incorporated in the fused debris rather than sorbed. In the upper cavity and chimney regions, where sorption is presumably the dominant process, the lab- oratory results and retention factors from field data are com- parable. The sorptive properties of tuff have been extensively studied (Wolisberg et al., 1979, 1981; Vine et al., 1980), and it has been demonstrated that there are minerals in the varieties of luff at the Nevada Test Site that exhibit excellent sorptive properties for cations. Such tuffs should provide a natural bar- rier against radionuclide migration to the biosphere. Most nuclides were found to sorb well on the geologic media studied; however, sorption of anionic species such as those of iodine, technetium, and uranium, which is frequently com- plexed by carbonate in the groundwater, is normally quite low for all geologic media (see Table 11.7). The chemistry of the actinides and lanthanides in groundwaters is complex and poorly understood. Research is necessary to achieve proper under- standing of actinide and lanthanide chemistry in near-neutral solutions for adequate prediction of transport behavior in nat- ural systems.
Radionuclide Migration from a Nuclear Explosion Cavity TABLE 11.6 Leaching Data for High-Graded Refractory Debris 145 Fraction Leached Ground Material Chunks Test Location: U3km U3ki U7ap U7ap Nuclide Shaking Time (Days): 23.6 23.6 35.3 35.3a o4Mn 2.9 x 10-4 9.0 x 10-~ taco 4.4 x 10-4 9.6 x 10- 5 ssy <8 x 10 - ~ <6 x 10 - ~ <8 x 10 - 4 <2 x 10 - 4 9~Zr <8 x 10 - 6 <2 x 10 - 6 <4 x 10 - 5 <5 x 10 - i°6Ru 9.6 x 10-~ 3.1 x 10-~ 5.1 x 10-~ 1.3 x 10-~ 4sb 5.0 x 10-3 2.6 x 10-3 2.5 x 10-4 4.4 x 10-4 5.6 x 10-3 2.9 x 10-3 9Te,n 2.7 x 10-3 1.8 x 10-3 9.6 x 10-3 1.5 X 10-3 3lI 2.0 x 10-2 1.4 x 10-2 8.8 x 10-3 7.8 x 10-3 37Cs <2 x 10 - 3 <2 x 10 - 3 40Ba 6.5 x 10-' 5.1 x 10-5 2.2 x 10-4 9.6 x 10-~ 4iCe <2 x 10-6 <1 x 10-6 <4 x 10-6 <3 x 10-~ slw 1.1 x 10-2 3.8 x 10-3 1.2 x 10-3 3.5 x 10-4 ssw 7.7 x 10-3 4.5 x 10-3 ls2Ta ~3 x 10 - 4 <2 x 10 - 4 237u 2.5 x 10-3 1.2 x 10-3 6.1 x 10-4 2.6 x 10-4 239 240pu <6 x 10- 6 <5 X 10- 6 aSolution and container were purged with Ar before leaching. The transport of tritium, which is assumed to have a distri- bution coefficient of zero, took over 2 yr to reach RNM-2S. We estimate that more than 13 yr would be required at current pumping rates for a hypothetical radionuclide with a distri- bution coefficient of only 1 mL/g to travel the 91 m between the explosion zone and the satellite well. The laboratory ex- periments indicate that most elements have Kit values much greater than this (see Table 11.7) and would not be expected TABLE 11.7 Distribution Coefficients for Alluvium and Bentonitea in water from the satellite well for many years. For example, strontium has a Kit of approximately 200 mL/g and would not reach RNM-2S for 1500 yr. Nonequilibrium ejects or the pres- ence of colloidal or other nonsorbing species might allow some nuclides to move more rapidly than expected; therefore, mon- itoring for radionuclides in water pumped from RNM-2S is . . . continuing. Distribution Coefficient (mL/g) Alluvium Bentonite Element Sorption Desorption Sorption Desorption U(VI) 6 60 200 170 Sb 6 80 7 50 Sbb 30 220 MOb 20 Ib 0.15 4.6 Sr 220 180 1700 2500 Rub 10 300 Nb 1900 3500 1000 2200 Ba 3800 4000 4000 6000 Cs 8000 8000 1800 2200 Co 9000 21,000 1300 7000 Ce >20,000 >2000 >500 >2000 Eu >5000 >2000 > 1400 >6000 aData from WolEsberg (1978) and WolEsberg and Wanek (1982). bTrace water produced by leaching test debris.
146 SUMMARY AND CONCLUSIONS The source term for radionuclides in the region of the Cambric nuclear explosion has been determined. Drillback cores were obtained and analyzed, and water was pumped trom several vertical zones and analyzed. Most of the radioactivity produced in the test was found to be retained in the fused debris with only low concentrations in the water that had been in contact with the debris for nearly 10 yr. Most of the radioactivity and the highest specific activities of all radionuclides were found to be in the region of the original explosion cavity. No activity was found 50 m below the cavity. Water from the region of highest radioactivity at the bottom of the cavity contained only tritium and 90Sr at levels higher than the recommended con- centration guides for water in uncontrolled areas. During nearly 6 yr (over 1.5 billion gallons of water) of pump- ing from a satellite well located 91 m from the Cambric cavity, only tritium, which is present as HTO and chemically the same as the water, and War, which seems to be dissolved in the water, have been positively identified in water removed from this well, although there is some evidence for the possible migration of minute amounts of t06Ru. These results are con- sistent with laboratory studies, which indicate that in general radionuclide sorption is sufficiently high to preclude the mi- gration of such nuclides from the original cavity to the satellite well in the near future. Pumping and radioassay of water from the satellite well will be continued to investigate the possible arrival of nonsorbing species. ACKNOWLEDGMENTS DARLEANE C. HOFFMAN and WILLIAM R. DANIELS BE FERE NC E S Borg, I. Y., R. Stone, H. B. Levy, and L. D. Ramspott (1976). Infor- mation Pertinent to the Migration of Radionuclides in Ground Water at the Nevada Test Site, Part 1: Review and Analysis of Existing Information, Lawrence Livermore Laboratory Report UCRL-52078. Coles, D. G., and L. D. Ramspott (1982). Migration of ruthenium-106 in a Nevada test site aquifer: Discrepancy between field and labo- ratory results, Science 215, 1235-1237. Hoffman, D.C. (1979). A field study of radionuclide migration, in Ra- dioactive Waste in Geologic Storage, S. Fried, ea., ACS Symposium Series No. 100, Am. Chem. Soc., Washington, D.C., p. 149. Hoffman, D. C., R. Stone, and W. W. Dudley, Jr. (1977). Radioactivity in the Underground Environment of the Cambric Nuclear Explosion at the Nevada Test Site, Los Alamos Scientific Laboratory Report LA-6877-MS. National Interim Primary Drinking Water Regulations, 40 CFR 141 (1978). Sauty, J.-P. (1980). An analysis of hydrodispersive transfer in aquifers, Water Resour. Res. 16, 145. Standards for Radiation Protection (1977). ERDA Manual, U.S. En- ergy Research and Development Administration, Chap. 0524. Vine, E. N., R. D. Aguilar, B. P. Bayhurst, W. R. Daniels, S. J. DeVilliers, B. R. Erdal, F. O. Lawrence, S. Maestas, P. Q. Oliver, J. L. Thompson, and K. WolEsberg (1980). Sorption-Desorption Studies on Tuff. II. A Continuation of Studies with Samples from Jackass Flats, Nevada and Initial Studies with Samples from Yucca Moun- tain, Nevada, Los Alamos Scientific Laboratory Report LA-8110- MS. WolLsberg, K. (1978). Sorption-Desorption Studies of Nevada Test Site Alluvium and Leaching Studies of Nuclear Test Debris, Los Alamos Scientific Laboratory Report LA-7216-MS. WolLsberg, K., and P. L. Wanek (1982). Laboratory and Field Studies Related to the Radionuclide Migration Project October 1, 1980- September 30, 1981, W. R. Daniels, ea., Los Alamos National Lab- We are indebted to the many individuals from Los Alamos and oratory Report, LA-9192-PR. Livermore National Laboratories, the U.S. Geological Survey, WolEsberg, K., B. P. Bayhurst, B. M. Crowe, W. R. Daniels, B. R. the Desert Research Institute, and other organizations who Erdal, F. O. Lawrence, A. E. Norris, and J. R. S myth (1979). Sorp- . . 1 . . . 1 ~ ~ , . , ~ ~ . tion-Desorption Studies onTu~. I. Initial Studies with Samples from participated In tins stuay aria wnose results are ~nc~uaea In this paper. The encouragement of the Nevada Operations Of- fice of the U. S. Department of Energy, and particularly of R. W. Newman, is also gratefully acknowledged. The results in this chapter represent data and interpretations available in De- cember 1981. the J-13 Drill Site, Jackass Flats, Nevada, Los Alamos Scientific Laboratory Report LA-7480-MS. WolLsberg, K., R. D. Aguilar, B. P. Bayhurst, W. R. Daniels, S. J. DeVilliers, B. R. Erdal, F. O. Lawrence, S. Maestas, A. J. Mitchell, P. Q. Oliver, N. A. Raybold, R. S. Rundberg, J. L. Thompson, and E. N. Vine (1981). Sorption-Desorption Studies on Tuff. III. A Con- tinuation of Studies with Samples from Jackass Flats and Yucca Mountain, Nevada, Los Alamos National Laboratory Report LA- 8747-MS.