Plutonium removing test from unpurified uranium solution in JRTF

JAERI's Reprocessing Test Facility (JRTF) had been operated from 1968 to 1969 and then spent fuel (U/Al metal, burnup 600MWD/T,U) from a research reactor (JRR-3) was reprocessed. The reprocessing tests were carried out successfully, and about 200g of highly purified plutonium (Pu) was recovered. Because a uranium purification system was not installed in JRTF, about 1,700L of unpurified uranium solution containing U (350 mg/mL), Pu (1.0 x 10-3 mg/mL) and beta (gamma) nuclides was generated from these tests. It was necessary to remove Pu from the unpurified uranium solution for interim storage in JAERI's Waste Treatment Facility (JWTF). JAERI and Unitika Ltd. have jointly developed an inorganic adsorbent, which has good properties to remove Pu from reprocessed liquid wastes. Based on the results of laboratory-scale tests, JAERI constructed the engineering-scale apparatus using the inorganic adsorbent for the unpurified uranium solution in FY 1995. The cartridge consisted of 65 wt% of fibrous activated carbon (FAC), which had the specific surface area of approximately 2,000 m2/g and high hydrophilicity and 35 wt% of inorganic binder. The treatment capacity of the apparatus was 22L/batch. The treatment of 1,700L of liquid was completed in FY 1997. The adsorbent showed high selectivity for Pu in the liquid waste containing a large amount of U. Pu removal efficiency was up to 95% and amount of adsorbed Pu was 0.02-0.03 mg-Pu/g-FAC. It was confirmed that the inorganic adsorbent had an excellent ability to remove Pu from reprocessed liquid wastes on an engineering-scale. As the inorganic adsorbent consists of inorganic binder and FAC, which component is more than 90% of carbon, it is easily reduced the volume by incineration. Therefore, it is possible to expect useful applications from the standpoint of volume reduction of the radioactive waste contained TRU nuclides. (J.P.N.)