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Show ENERGYfoUPPATE CAN WE SAFELY DISPOSE OF NUCLEAR WASTES? By Floyd Culler ;T hJCT- J By Floyd Culler Floyd Culler, president of the Electric Power Research Re-search Institute, spent 30 years with Oak Ridge National Na-tional Laboratory. He has been elected to the National Nation-al Academy of Engineering, and is a fellow of the American Amer-ican Institute of Chemists. There are ways to dispose of radioactive wastes safely which have been technically demonstrated at small scale. The science and technology is available to permanently sequester the wastes. But the controlling factor is public perception and acceptance ac-ceptance of the possible technical solutions. Public knowledge and understanding understand-ing of the issues are, in part, confused by many wrong impressions about the nature na-ture of and the potential hazards of radioactive wastes, when fixed as insoluble insol-uble glass and stored in small zones of geologically stable parts of the earth. I think that the best solution for disposal of high-level waste starts with making insoluble glass or ceramics from the residues produced, following reprocessing repro-cessing of fuel from nuclear plants. These glasses, protected pro-tected in corrosion-resistant containers, can be placed in carefully selected geological formations, such as salt beds or dry enclosures in granite rocks. The reprocessing step removes valuable plutonium and uranium from the wastes and returns these fuels to a reactor where they undergo fission to generate gen-erate power. If wastes are stored in deep salt beds, there is no problem of contaminating normal water supplies, because be-cause all of the normally used water occurs in the first few hundred feet below the surface of the earth, particularly in regions where disposal is considered. These deeply buried, stable, and geologically protected beds are most useful where they are from 1,000 to 3,000 feet deep and are sandwiched sand-wiched between hundreds of feet of very tight layers of shale. Many such natural deposits exist which extend for thousands of square miles. The layers of shale, salt, and again, shale were put down by the great inland in-land seas 300 million years ago. Obviously, the salt beds would not exist if water flowed there, because salt is soluble. The salt is protected pro-tected from water intrusion, glaciers of the ice ages, and surface floods by thick layers of shale. The salt layer itself is very slightly h: Floyd Culler plastic (somewhat like candle can-dle wax); if dug or cracked, it will reseal itself. Actual subsurface area required re-quired for nuclear power waste disposal is very, very small. If the United States were to build 1,000 reactors in the next 20 years, which is now extremely unlikely, the accumulated ' wastes from all of these plants could be stored in about 1,200 acres of salt under the ground. Compared to this requirement, one single deposit de-posit of bedded salt covers about 10,000 square miles, or 6,400,000 acres. In these 1,200 acres, the nuclear wastes would be contained in six-inch cylinders, cylin-ders, ten feet long, placed on 25-foot centers, so that most of the area would be occupied by salt between the canisters. So, there certainly cer-tainly is no problem insofar as availability of a safe disposal dis-posal site is concerned. There are other formations, forma-tions, such as granites, tuffs, limestone caverns and, for low-level wastes, the tight shales which will protect radioactive wastes. Unreprocessed fuel elements ele-ments from the , reactors now operating can be stored very safely in heavily protected pro-tected water-cooled, or air-cooled, air-cooled, basins at or near the earth's surface. The current practice of storing unreprocessed unrepro-cessed power fuel is the necessary first step in an acceptable nuclear waste disposal scheme. But I think the safest course of all is to reprocess the fuel elements after they have been removed from the nuclear reactor. The residual plutonium and uranium can then be used to produce more nuclear fission power. This would remove those long-lived radioactive elements, ele-ments, leaving only those shorter-lived fission products prod-ucts which decay to innocuous innocu-ous levels in 1,000 years or less. Such innocuous levels would be about equal to a natural source, such as the uranium ores on our Colorado Colora-do Plateau. |