Dissolution behaviour of simulated MOX nuclear fuel pellets in nitric acid medium

Data on the kinetics of dissolution of (U, Pu) mixed oxide (MOX) fuel pellets in nitric acid is an essential information required for the design of continuous dissolution system for the reprocessing of fast reactor spent fuel employing the plutonium uranium extraction (PUREX) process. In this article, the results obtained from a systematic investigation carried out on the dissolution of solid solutions of simulated (U, Ce) MOX pellets in nitric acid, with Ce as the non-radioactive surrogate of Pu, is presented. The influence of initial concentration of nitric acid, rate of mixing and temperature have been studied under typical PUREX process conditions. The apparent activation energy was found to be about 26 kJ/mol/K. The composition of the gases liberated (NO_X) during dissolution was measured which is required for understanding the mechanism of the reaction.