RECOVERY OF FISSION-PRODUCT PALLADIUM FROM ACIDIC HIGH-LEVEL WASTE SOLUTIONS

The recovery of palladium from a synthetic pressurized heavy water rea ctor high level waste (PHWR-HLW) solution has been carried out, and th e best reagents to use for the actual HLW solutions are discussed. The extraction of palladium from nitric acid solutions has been carried o ut using Cyanex-471X (triisobutylphosphine sulfide, TIPS) as the extra ctant. The metal ion could be quantitatively extracted from solutions with nitric acid concentrations between 2.0 and 6.0 M. The species ext racted into the organic phase was found to be Pd(NO3)(2) . TIPS. Nitri c acid in the range of 2.0 to 5.0 M had no effect on TIPS for at least 71 hours. A systematic study of gamma irradiation on loading and stri pping of palladium from loaded organic phases using several potential extractants, TIPS, alpha benzoin oxime, dioctylsulfide, and dioctylsul foxide has been made. A flow sheet for the recovery of palladium from actual HLW solutions using TIPS is proposed.