A Study on the dry pyrochemical technique for the oxide fuel decladding

Abstract

In order to reduce the fuel recycle cost, advanced fuel reprocessing processes have been investigated. In those processes, it is required that the fuel feed should be pulverized and separated from the cladding material for the head end process. For this purpose, applicability of dry pyrochemical processing is investigated using the spent LWR fuel. The experimental results show that the UO2fuel irradiated up to 50GWd/t is well pulverized and recovered more than 99% at 480°0 heating in air flow. The MOX fuel with 4%Pu is also pulverized and recovered similarly. It is revealed that the time to fully oxidize the high bum-up fuel is nearly 10 hours. For the reasonable design of the plant, it is required to reduce the time and the survey results reveal that the higher heating temperature is effective to shorten the time. The removal ratios of the volatile fission products during pyrochemical processing are assessed experimentally and the results show that additional heating of the recovered fiiel should be necessary to remove the majority of the major volatile fission products. Based on the experimental results, a concept of the head end process for 200t-HM/year plant are proposed.