aIAEA, International Atomic Energy Agency; ASA, United States of America Standards Institute.
bMPCp, maximum permissible concentration for members of the population at large; MPC0, maximum permissible concentration for 40-hr work week occupational aIAEA, International Atomic Energy Agency; ASA, United States of America Standards Institute.
bMPCp, maximum permissible concentration for members of the population at large; MPC0, maximum permissible concentration for 40-hr work week occupational exposure.
wastewater flocculation, precipitation, sorption, filtration, and ion exchange can be adapted to radioactive wastes. Typical removals (Straub 1964) of mixed fission products and individual nuclides are shown in Table 8.7.2. Common methods for mixed fission product precipitation are aluminum salts, iron salts, tannic acid with lime, phosphate with lime, ferrocyanides, and excess lime-soda ash.
When wastes are segregated, specific treatments for radioactive isotopes include strontium, combined calcium, nonradioactive strontium-iron phosphate, or hydroxide at pH 11.5, tannic acid, and nickel ferrocyanide; cesium, nickel ferrocyanides, nickel ferrocyanides, and copper and iron ferrocyanides; and ruthenium, nickel, copper, or iron ferrocyanide. Processes are chosen based on local considerations to obtain a high degree of radioactivity removal at a high floc settling rate, with a minimum sludge volume and a maximum degree of economy.
Decontamination factors of 10 may be obtained for mixed fission products and decontamination factors of 200 for specific isotopes with a specific treatment. Provision must be made for discharging decanted water and for drying, packaging, and storing sludge from coagulation and precipitation. Residues are presently sent to an approved commercial burial site.
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