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The Disposal of Radioactive Waste on Land (1957)
Board on Radioactive Waste Management (BRWM)

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91
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91

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~ - 91. APPENDI;K D COMMITTEE ON SHALLOW DISPOSAL . .. SUMMARY MINUTES OF MEETING OF SEPTEMBER 11, 1955 Called to order at Il:00 A.M. by Dr. John C. Frye, Chairman of Committee. ATTENDANCE For fun names and affiliations consult List of Participants. PROCEEDINGS Abelson Frye MacMurray Benson Goldich Morton B ranson Hunt NeweU Brown Inger son Piper Bryant Jenkins Prescott Clark Kohman Riley Claus Casky Roeilder Cramer Lat;ta Stru~ess Curtis Liebermar~ Theis Curtiss Loofbourow Thomas, Harold A., Jr. Thomas, Henry C. It was agreed that the subject would be broken down into categor- ies based on geologic en~nro~ent, ancl the following four general categories were set up: a. Surface excavations b. Castration into shaHow permeable beds c. Natural and artificial excavations, inClUrling mines d. Artificial solution cavities (principally In salt) During the proceedings it was decided to include the cavities in salt (category D) in category C. 2. Surface excavations. The estimate of I, 000 gallons of waste per day for a one megawatt reactor was used as a yardstick for all the forgoing discussions.

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92. A. Quarries In gra~te and other cryst~;ne rocks. (1) Advantages Availability. There are numerous abandoned granite quarries in many parts of the country (e.g., Texas, Minnesota, etc. ~ . LOW cost of acquiring and preparing disposal site. Recoverability of material if it is wanted. If the quarry is tight, the material will not move. (2 ~ Hazards Contamination of ground water or of atmosphere by leakage or by sucking up of material ~ tornadoes. Vulnerability to bombing. (3) Problems and unknown factors a. Effectiveness of a grout curtain to prevent seepage into ground water. It was doubted by the engineering geologists present Mat any grout curtain is 100 per- cent effective. b. How could such a site be effectively monitored, an apparent necessity in any jointed crystalline rock? c. Can the wastes be made self-sealing and thus provide their own "grout" curtain? Apparently this cannot be aIlewerec] at the present time . Current waste s are high ~ alwn~m salts, which might be useful In self- seal~g, but power reactors will undoubtedly have wastes high In zirconium or starkest steel. More re- search is needed on self-sealing possibilities. (4) Conclusions It was the opinion of the majority that both grouting and self-sealing are probably unreliable. Granite quarries are feasible only if the wastes can be per- manently immobilized. (5) Significant parts of discussion learning to above summary. Golaich: There are a number of granite quarries which might be used, especially In Texas or Minnesota. You could combine surface disposal with self- sealing . ~ favor surface disposal because you know where it is. A pit 100 x 200 x 50 feet coma hold a minion gallons.

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93. never saw a quarry that was water tight. ~ know where it ~s and that it isn't going to move around. It cloesn't have to be granite, it can be any firm rock. The health agencies are going to insist on some spec- ifications. It carmot leak into ground water which wig be used for drinking or irrigation. It cannot be a source of contamination of the atmosphere. Winds have a way of whipping up a lot of surface water into the atmosphere. A tornado could 'luck up the total contents and spread them over the landscape. A cover would be indicated. (AEC) , .. . - What would be needed would be a test of the pit with tracers, over a period clef time equivalent to the length of storage time. Monitoring ~ jointed rock would be difficult. Some method should be used to immobilize the wastes grouting, self- sealing, etc . One of the fi r st prope rtie ~ Deco b e de te amine ~ i s the leaching qualities of the sauntered wastes. Hatch at BrooRhaven has information on leaching from montrnoriHonite clay. ., . . .. ... When we talk about self-se:~ing, we have to remember that alum nurn is In the picture because aH reactors now are research reactors; with the high temperatures ~n- volved in We power field, the wastes will be zirconium or stainless steel. bunion Carbide and Carbon). Anything on the surface is going to make an attractive military target. The current system of storing ~ tics presents the same hazard. Another surface basin might be a lake, or a large ile- pression We Death Valley.

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94. ~- Death Valley is an active seismic area. There has been a movement of about 350 feet in front of the Funeral Range in the last thousand years. Granite quarrie s seem to be open to the ob jection that you never know whether it is actually tight . How about grouting granite? No grouting or facing job is perfect. If grouting were the factor on which we were going to rely, I'd hate to be the one to approve it. ~ have had lots of experience and have no faith in it, beyond its specific capabilities. (Pre scott) Chairman: Is the consensus on crystalline rock quarrie s that the wastes shouic3 be self-sealing or immobilized' If grouting isn't satisfactory, how can you rely on self- sealing as satisfactory 5 (Prescott) Consensus: Self-sea}ing and grouting are unreliable, and granite quarries Louis be acceptable only i! the waste is permanently immobilized. B. Excavations In permeable non-c rystaHine rocks such as sand- stoue, limestone, coal, etc. These sites appear to have all the disadvantages of granite quarries ~ a magnified form . It would be virtually impossible to seal them so that liquid waste s would not contaminate groom water supplie s . They are not worth considering unless the waste can be permanently immobilized ~ a solid form. Excavations in non-permeable materials -- clays and shales. (~) Shale pits appear to have am the advantages of granite quarrie 8 piUS Me po s sibiH~ Mat Hey might be mace "tight" more easily by self-seal~g, adsorption, etc. It was also suggested that a non-radioactive sealing mate- rial might be found for clay or shale, thus producing a membrane or lining for the pit. (2) Hazards and Problems. AH rocks, including shales, are so variable that it Louis be difficult to guarantee the

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95. sealing of any pit. Adsorption by the clay minerals seems to show signs of promise, but in the ground this reaction is reversible and therefore not reliable as a "sealing" method. Long motto ring of low-level wastes may give valuable data on these problems. (3) Conclusions. Disposal in shale pits is too risky ~ our present state of knowledge. The method, however, may have promise, and continued research on adsorption and sealers is recommended. (4) Significant parts of the discussion leading to above sum- mary. If the material is placed in shale pits, deposition of solids will occur at the bottom and produce seating there. The clear supernatant with some high radioactivity ~11 pass out the sides. Can we assume pH control? Only at great cost Id increase in volume. {ORN16} The question has been raised of the effect of zirconium and the possibility of zirconium recovery. Zirco~iiuln is tetravalent and has a high replacement value for other. adsorbed ions and would displace the strontium. Couldn't we use nonradioactive material to seal and then place in it the radioactive material? Then the mem- brane would be self-sealing . Ideal conditions are being assumed. There is a great variation in rocks in their cementing abilities to the ex- tent that probably no one would place his ';tarnp of ap- pro~ral on it. If the shale is thick anti stable it might be a goof! gamble, since it could be monitored. Sealing clepends on the interaction with the rock. Dilu- tion may damage the gel.

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96. 6 1 You may bond up a concentration of radioactive mate- rial in the gel and get a high heat. Does anybody have my ideas on what would happen by throwing some benton~te ~ this material to help it gel? intonate loses its properties in acid solutions. Is there a geologist present who knows of a clay de- posit ten feet thick, without bedclirlg plies and fractures? (No volunteer s ~ In propane storage we can take a slight i088 but here we're taming about zero leakage. ~ don't trust any natural material not to leak. Everyone seems to agree that for any processed that you do which depends on plugging pores, the period of testing would be so long that it ceases to be of interest. Consensus: Without research, shale is not safe. T"filtration into shadow permeable beds. - A. Beds below the water table. (~) Aquifers below the water table could be considered only in isolated desert bash areas like those of Nevada, and even here they have no advantages over deep aquifers. In addition, they have more potential problems Can the deep strata, e.g.: (a) ~ closed basins the 801UtioD-S niight rise to the surface ~d evaporate; ib} even ~ des- ert areas, shaHow aquifers are con~noMy used as water supplies: (c) we ~losl't loom enough about the movement of grown water ~ these basins. (2) Current experiments on ads orpticn indicate that about 20 tons of mon~oriDo~te cIat may be enough to adsorb I, 000 gallons of waste, mostly by base excl~ge. The reaction, however, is reves''ible. (3) Conclusion. Di';posal in shallow aquifers below Me water table is not recommended. It would be possible

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97. only if further tests on adsorption Delicate that the radio- active ions mill not migrate any great distance. Even In this event, disposal In deep aquifers would be safer. (4) ~ Significant parts of discus sion leading to above summary . Chairman: Infiltration of material close to the surface into permeable Ed semipermeable formations: A good estimate of adsorption capacitie s word be twenty tons of clay for complete adsorption of one thou- sand gallons. How much clay is there in the desert basins ? (Henry Thomas ~ cieserts there are thousancis of cubic miles of clay. ~ would not trust desert basins which appear to have no natural drayage. Even if the bash is not closed, if the time is long enough in getting over the rim, isn't this adequate? In these basins there are grave} layers extending out from the mounter like tongues {illustrated by ~nteriock- ing fingers pointing the tips downward). There are gravel and clay in about fifty-foot layers. Each gravel layer has perched water. Has any estimate been made of the age of these waters ? There wouic] be stratification and mixing from weDs. If you are thinking of tritium measurements, these would be very diifficult. Consensus: We consicler disposal In permeable beds - should not tee done below the water table, uMess subse- quent information ~ndicates that adsorption w~H protect the aquifer above. B. Beds above the water table. (~} Possibilities. A part of the committee was of the opinion that this might be worth trying ~ isolated desert areas

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- 98. . where the test could be monitored effectively. Areas suggested were: an isolated mesa on the Colorado Plateau; the edge of a fangiomerate, where gravels in- terf~nger with clays; and an area underlain by loess. During the discussion, it was apparent that the feasibil sty of these sites was predicated on the assurnution that _ =_ ~ ~ O and an area underlain by clay minerals would adsorb the radioactive ions. stick for the dis cus sion was: A cubic mile of semi- loess . ~ , Chin ~ -' 4' - Yard- consolidated material conta~ns about 104- tons. 11 the material has ~ percent montmorillonite, it would adsorb I, 000 gallons a day for I, 000 years . a. The Colorado Plateau was deemed a poor place for carrying on the experiment, because too little is known about the movement of ground water in the aquifers there. The material might find its way to surface springs too quickly. b. The f~giomerate at the edge calf a desert mountain range Louis be a suitable test site, if preliminary laboratory te sts are favorable . c. A Ic~ess-covered area would be good if it is sufOcientlv lo ~ . . . ~sotatect, anct z~ the preliminary tests are favorable. (2} Recommendations for tests and requirements. a. "Cool" the waste for a period of several years. b. Conduct specific retention studies on loess and other materials . c . Conduct research on tracers to determine rate s of ground water movement through unsaturated materials and movement of cations in the water. Helium was suggested as a tracer. d. Laboratory studies con cation movement as related to heat effect. (3) Conclusions. This method] of disposal is worth investi- gating, but cannot be recommended at the present time. Extensive research win be needled, with no guarantee of succes s .

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2: 99. 4. Natural caverns and artificial excavations, rescinding artificial solution cavities. A. NaturalCaverns. NaturalCaverns are in the zone of potable water and leak like sieves. They are totally unsuitable for clisposal of ~iqwd wastes . They would be usable for dry im- mobilized wastes. Also, a dry cavern above water table would be suitable for dry wastes that were not immobilized but that were suit ably packaged. B. Abandoned Mines. (~) Shallow mines are similar to caverns in that most are wet and even the dry ones would probably leak if filled with liquid wastes. Evaporated solids in earls could be stored in shalHow dry mines . (2) Deep mines are commonly below tne water table and are dry. A deep dry mine (not on a fissure rein deposit) Would definitely be suitable for storage of ctry wastes in containers and might be suitable for liquid wastes. Heat would be a problem, but could probably be solved. One difficulty would be to fad a Mae that the owners womb be willing to abandon. 3 ~ Significant parts of discus sign. Abandoned mines are vary close in structure to natural caverns . Real- deep mines are dry. Cannel! peaches have been taken from mines after twenty years' storage and the cans are still bright and shiny and free of rust. Deep mines might be difficult to obtain because they are expensive and, even if unused, the owners might be reluctant to part with them. There is a mine ~ Ontario in a pre-Cambrian formation in the midge of a lake. No water has ever beer pumped from it. If deep, cry, non-ve~ mines below the zone of ground water table con be found, they may be suitable. If the

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100. site is satisfactory this would be worth looking into for liquid wastes. Mines are also very promising for solid storage. C . Special Excavations, including solution cavities in salt . (~) General statement. Special excavations have all the ad- vantages of mines except for their higher cost. In acidi- tion, we can choose the location, geologic horizon, geometry, etc. The cost of special shafts would be about $200 a foot for the main shaft with a 6 to 8-foot cliameter, $100/ft. for cross cuts, and$100/ft.for ventilation shafts. As in mines, heat dissipation wouicl be a problem, but the excavation could be designed to aid this dis,;inatinn . _,¢ ~ {2) Excavation of solid rock. Deep shafts in crystal rocks might be practical -- they womb have the same character- istics as creep abandoned mines. Also, it seems worth while investigating artificial excavations ~ shale. Al- though surface pits In the shoe are probably not leak- proof, excavations ~ Wick shale beds in Illinois have re- m~ed bone-dry since they were made (~oofbourow). It was the opinion of several engineering geologists that dry chambers can be excavated at relatively shallow depths in thick shale formations. A great clear of testing would be nece ssary, however, before one of these cavity ~ could be endorsed for the disposal of liquid wastes. Type of research needled is: mechani cal stretch tests of the particular formation involved, stability of the shale in the presence of the particular solutions, etc. The cost of propane storage in this type of cavity runs from 7 to 14 doDars a barrel. {3-~---Dis-s-oived cawLies In salt. Solution cavities In salt are probably the most promising sites for relatively shallow ;lisposal of liquid wastes. Both bedded salt any salt domes are pos Bible, although bedded salt would have more prob - lems, such as the greater difficulty of controlling the size and shape of the cavity and the additional testing of the roof and floor rocks. a. Advantages of salt cavities.

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101. Availability. There are numerous beds of salt in the mid-cont~nent area and hundreds of domes along the Gulf Coast. Acquisition cost wouici be low. Physical characteristics. Salt win flow under pres- sure, and ~ the salt domes would be self-sea];ng around cavities. Its high conductivity (about twice that of most rocks) aDd relatively high melting point (~° C at pressure of 760 man Hg) would help in heat dissipation. It-was stated that this type of storage Louis be developed at a cost of $3.50 per barrel. _ _ _,l, ,~ _ ~ - b. Hazards and uncertainties. Cavities and mien ~ becIded salt might be Abject to cave-=x; the strength of the roof rock would have to be carefully tested. Seismic activity might fracture salt of the domes and permit the escape of some waste before the salt re- sealed the fissure. c . Research needed. Extensive laboratory studies of salt under the heat ~d pressure conditions that would emit. Test also the idea of dissipating the heat by making the salt cavity act as a rend conclenser. DeterIs~iDe size, shape, and spacing of cavities to allow heat dissipation. Phase rule study of salt ~ presence of waste solu- tions . Migration of cavity along lines of stress by differ- ential solution. . - d. Conclusion. Solution caviled ~ mat domes are probably She best potential Bites for the disposal of liquid wastes at shallow depths. Caprices ~ salt beds are also good potential sites, but must be viewed with more caution. Rather extensive labora- tory tests win be necessary before dispose In salt can be attempted, but this research is pretty straightforward, and is pointed toward the question of how to do it rather than whether it cart be done. e . Significant parts of discus sion on salt. 1

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102. In Kansas six caverns were dissolved in bedded salt fifty feet thick for UP storage. These had a capacity of 25,000 barrels and were within 500 feet of each other ~ but not connected. A well for the disposal of the dissolved brine was clrilled at a cost of $80,000. The cost of the Orst cavern, including the weH, was $7.00 per barrel and for the remain- ing Ove, $3.00 to $3.50 per barrel. ~ Wink if conditions were favorable the cost could go down to fifty cents to a doHar a barrel. Do you have any idea of the shape of these caverns? There ' ~ no way of long . ~ don't think you can predict the shape because most beds are shot fun of fracture galleries. In Texas we have dissolved two caverns ~ salt, not bedded, of I.7 and 2 million cubic feet. The diameter is about 270 feet, as measured by sonar e - Oration . The depth is controlled using gas or clip cushion. ~ think you could probably get this for $20, 000 . In t:;~ada there is one which is eighteen feet deep, lens shaped, with a limestone roof. Salt domes can be written off as economically worthless because of huge arnour~ts of salt available. Salt has twice tide heat conductivity of soil, ~d a melting pout of 800° C. The liquid can be saturated and probably would stay there for years. . Put holes down into a dome, say thirty feet in di- ameter and one thousand feet deep. Keep them at, fifty pounds' pressure ~d let them operate as reflux condensers . Reflux action may take mete real from the top and place it at the bottom. Differential heating would re- move material from the the sides. Maybe the hole will crawl. think this wall work Ad I'd sure look into it.

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103. Would there be an evolution of chlorine gas ? No calcium sulfate usually is present . This can be te steel ~ the laboratory. ~ don't believe the renux condenser idea is a~y- th~g more than a wild dream. Use water or brine to dilute or any method! to get the heat into the body of the salt. However, there is an enormous calcu- lation on heat to be made. I'm lukewarm on salt beds but not on salt domes. There are two hatred and forty-two domes from Alabama to Texas. Some may be fifteen thousand feet thick, or more. Consensus: Salt storage is a preferred method for liquid disposal. Chairman: WiD someone summarize the research neede c! ? It would be nice to Ludlow how it ca" be done -- how many -- what spacing -- what control -- amber what conditions and how fast it would burrow with difference in heat up, down, ~d sideways. . 6 , .. , . , , ~ ~ .

Representative terms from entire chapter:

ground water