METHOD OF PRECIPITATING TECHNETIUM DIOXIDE FROM SOLUTIONS FORMED ON PROCESSING IRRADIATED NUCLEAR FUEL FROM NUCLEAR POWER PLANTS

摘要

FIELD: nuclear fuels technology. SUBSTANCE: in technetium-containing tailing aqueous nitric acid solutions formed upon regeneration of irradiated nuclear fuel, technetium is first stabilized in tetravalent state by adding strong reducing agent not forming complexes with technetium at reducer-to-oxidant equivalent ratio at least 1. Technetium is then precipitated in reverse precipitation mode together with fission products and actinide elements contained in technetium solution by adding hydrazine hydrate until pH 6.5-7.5 is reached, after which precipitate is filtered off, dried, and calcined under conditions preventing technetium dioxide oxidation. As a result, concentrates of fission elements (molybdenum, zirconium) and long living radionuclides (neptunium, rare-earth elements, and transplutonium elements) are solidified. EFFECT: avoided addition of salt-forming substances, achieved fullness of localization, and excluded volatility of technetium compounds in press-powder preparation stage. 9 cl, 3 tbl, 14 ex