AN APPROACH FOR EVALUATING EQUILIBRIUM AND RATE CONSTANTS FOR THE REACTION OF NP(V) WITH NITRIC-ACID IN THE PUREX PROCESS USING PROCESS DATA

A new approach for evaluating the apparent equilibrium and rate consta nts for the reaction of Np(V) with nitric acid by using the process da ta of multistage countercurrent solvent extraction experiments is prop osed. The numerical simulation of neptunium extraction in the co-decon tamination process of the Purex process is carried out on the assumpti on of the rate equation. The apparent equilibrium and rate constants a re determined by the nonlinear least-squares method with experimental data for multistage countercurrent solvent extraction with a numerical simulation code. The determined apparent equilibrium and rate constan ts are 1.25 to 1.97 x 10(-2) min(-1) and 6.04 to 11.5 x 10(-4) (l/mol) (3/2), respectively. These values are consistent with those obtained i n other kinetic studies.