Actinide, strontium, and cesium removal from Hanford radioactive tank sludge

A pretreatment flowsheet was tested for separating key radionuclide components from the sludge stored in one of the high-level waste tanks (B-110) at the Hanford Site; this sludge resulted primarily from the bismuth phosphate process, which was one of the three major plutonium separation processes used at Hanford. This test involved 1) washing with water, 2) caustic leaching, 3) acid dissolution, 4) separation of transuranic elements (TRUs) by extraction with octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), 5) separation of Sr by extraction with di-t-butylcyclohexano-18-crown-6, 6) separation of Cs from the acid-dissolved sludge solution by treatment with ammonium molybdophosphate (AMP), and 7) separation of Cs from the sludge wash and caustic leach solutions by ion exchange using a phenol-formaldehyde resin (CS-100). The results of the radionuclide separation steps indicated that the proposed flowsheet is a viable approach to pretreating the sludge stored in tank B-110. The TRUs, Sr-90, and Cs-137 were separated from the bulk of the sludge components, so that most of the mass of the sludge (containing Al, Bi, Fe, Na, etc.) could be disposed of as low-level waste.