(2a) Purification of Simulated Neptunium Filtrate Solution by Anion Exchange

Anion exchange was investigated as a means to recover and purify neptunium (Np) from solutions containing significant plutonium (Pu), sodium (Na), and manganese (Mn) impurities and a high nitrate concentration. The solution being evaluated resulted from lean filtrate and precipitator cleanout solutions which were generated during Np processing at the Savannah River Site. Prior to anion exchange, valence adjustment of the Np using ferrous sulfamate (i.e., Fe2(SO3NH2)2 or FS) was evaluated. For testing, a simulated filtrate solution was made with ~1.5 g Np/L and slightly elevated levels of impurities. Two anion exchange column runs were performed. In both runs, Np was loaded onto Reillex HPQ resin in high nitric acid (HNO3) solution, typical for Np processing. The resin wash step differed in the two runs, but the elution step was the same. In the first column run, 12 column bed volumes (BV) of reductive or partition wash with 6.4 M nitric acid / 0.05 M FS were used. In the second run, six BV of 5 M HNO3 / 0.05 M FS were used as the reductive wash. Reported results will include Pu rejection, Np losses and decontamination factors for Na and Mn.