Development of advanced reprocessing system using highly selective and controllable precipitants, 21; Precipitation behavior of Pu at U-Pu co-precipitation step

Kim, S.-Y.*; Morita, Yasuji  ; Kawata, Yoshihisa*; Ikeda, Yasuhisa*; Kikuchi, Toshiaki*

We have been developing an advanced reprocessing system for spent FBR fuels based on precipitation method using pyrrolidone derivatives. The system composed of the first precipitation step for selective U separation with N-n-butyl-2-pyrrolidone (NBP), concentration step and the second precipitation step for Pu and residual U separation with N-neopenthyl-2-pyrrolidone (NNpP). The present study revealed the effects of heating in the concentration step, Pu concentration and Pu oxidation state, on the Pu precipitation behavior in the second step. Experimental results showed that residual precipitant from the first step is decomposed in the concentration step and the products would reduced the precipitation yield of Pu(IV) in particular.