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CHAPTER 1 PHYSICAL AND CHEMICAL PROPERTIES OF WASTES PRODUCED BY ATOMIC POWER INDUSTRY CHARLES E. RENN, The Johns Hopkins University Department of Sanitary Engineering and Water Resources THE ULTIMATE forms and radioactivities of wastes delivered for sea disposal will be deter- mined by conditions that have not yet been fully evaluated. Present and projected wastes will undoubtedly be modified by requirements for storage, transport, and economical handling, and the ultimate form of wastes with which we may be concerned will be further conditioned by what we learn in early disposal practice. The following represents the characteristics of high- level reactor wastes that now exist, and which are likely to appear soon. The primary radioactive wastes result from the chemical extraction of inhibitory fission products from metallic reactor elements. A strong nitric acid solution of aluminum heavily contaminated with a variety of fission products is obtained after the useful reactor fuel is re- covered. To conserve tank space and shielding, the solutions are concentrated by evaporation. Where storage is to be made in steel containers, the solution may be neutralized and made slightly alkaline with commercial caustic. A neutral or alkaline salt solution or slurry is developed — the concentration of salts may ap- proach or exceed saturation values at storage temperature. The neutral salt concentration of the waste determines its density. Some types of reactor elements are not directly soluble in nitric acid and require solution in combinations of other mineral acids and catalysts; most ulti- mately require conversion to nitrates before complete extraction, however. The cladding and alloying metals of the reac- tor elements are also discarded in the wastes. Aluminum is the most common and abundant of the metals used; it appears in concentrations as high as 80,000 ppm. in final wastes. Zir- conium will also be present. Of the various non-radioactive components in the wastes, the properties of the high-density- producing salts, of the high nitrate concentra- tions, and of aluminum are of greatest interest. The presence of these at present limit the prac- tical production of selectively adsorbed fission waste products. If the wastes are concentrated for economical storage and transportation and neutralized to limit corrosion, the densities of the waste liquids will exceed that of sea water. The temperatures for precipitation of super- saturated salts in the various wastes are not known, but it may be assumed that further sludges will be formed on cooling to deep sea temperatures — some corrosion-product sludges already exist. The solubilities of both normal and radio- active components of the waste will be condi- tioned by the presence of nitrates in concentra- tions exceeding equivalence. Aluminum nitrate precipitates as a light floe in sea water at con- centrations as low as 1 ppm. Al. At present there are no data on its solubility in a sea water waste mixture. Neither do we know what the adsorption characteristics of the aluminum floe in sea water may be. The range of physical and radiochemical characteristics that may be anticipated in con- centrated fuel re-processing wastes and approx- imate quantities of wastes produced are indi- cated in the three tables following. 26
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Chapter 27 Properties of Atomic Wastes TABLE 1 GROSS PHYSICAL AND CHEMICAL CHAR- ACTERISTICS OF STRONG AQUEOUS WASTES FROM REACTOR FUEL RECOVERY PROCESSES l (Concentrations of non-radioactive components before evaporation, neutralization, and treatment for fission removal.) Range of Molar Concentrations 0.07 - 7.0 0.04 - 1.6 0.05 0.03 - 0.5 0.05 - 2.0 0.01 - 1.0 0.03 0.02 0.001 0.001- 0.01 0.05 - 3.0 0.14 - 7.0 0.2 - 0.5 1.07 - 1.25 80 -5200 Component H Al Fe Zr NtV Cr Ni Sn Mn He . F NO,- SCV Specific Gravity (unconcentrated) . Curies/gal. (100 days cooling).. BTU/hr./gal. (10 days cooling— 50% gamma, 50% beta) 1.37 - 29-4 1 From Tables 4 and 5, Status Report on the Dis- posal of Radioactive Wastes, ORNL-CF-57-3-114, F. L. Culler. TABLE 2 SHORT-LIVED FISSION PRODUCTS PER 1000 GM IP* REACTOR CHARGE AT 100 DAYS COOLING WITH 30 PER CENT BURNUP 1 Fission Half products life2 Y-90 62 h Rh-106 30s Ce-144 275 d Zr-95 65 d Nb-95 35 d Y-91 57 d Sr-89 55 d Ru-103 45 d Ce-141 28 d Ba-137 2.6m Ru-106 290.0 d Pr-143 13.8 d Ba-140 12.5 d La-140 1.7 d 1-131 8.0 d Beta Grams curies 4.63 748 0 1,514 4.90 16,332 1.52 32,647 1.61 63,657 1.11 28,239 0.86 23,253 0.46 13,236 0.45 10,004 0.35 0.02 0.02 1,514 1,465 1,222 1,222 23 Gamma curies 515 4,900 62,356 65,657 6,618 20,008 508 305 1,331 29 Total 15.93 195,076 162,227 1 From presentation by F. L. Culler, Oak Ridge Na- tional Laboratory, before Meeting on Ocean Disposal of Reactor Wastes, Woods Hole Oceanographic In- stitution, August 5-6, 1954. 2 Abbreviations are s for seconds, m for minutes, h for hours, and d for days. TABLE 3 LONG-LIVED FISSION PRODUCTS PER 1000 GM U"5 REACTOR CHARGE AT 100 DAYS COOLING WITH 30 PER CENT BURNUP l Half Fission products life Grams Cs-137 33 y 7.05 Sr-90 25 y 4.63 Pr-144 17 m 4.90 Te-129 72 m 0.03 Total long-lived 16.61 Inactive fission products.. 230.00 2 Short T i 15.93 Beta Gamma curies curies 563 — 748 — 16,333 17,966 1,217 2,435 18,861 20,401 198,564 152,325 Grand total 262.54 217,425 172,726 1 From presentation by F. L. Culler, Oak Ridge Na- tional Laboratory, before Meeting on Ocean Disposal of Reactor Wastes, Woods Hole Oceanographic In- stitution, August 5-6, 1954. 2 Short-term fission products from table 2.