Impact of impurity in transmutation cycle on neutronics design of revised accelerator-driven system

Partitioning and transmutation technology will be a promising technology to reduce the burden of the geological disposal of the high-level radioactive waste. The Japan Atomic Energy Agency has investigated a lead-bismuth eutectic cooled accelerator-driven system (ADS) to transmute minor actinides (MAs) in the transmutation cycle. This study aims to revise the ADS design and to investigate the impact of impurities in the transmutation cycle on the ADS neutronics design. The impact of impurities in the transmutation cycle is investigated for the revised design. For the uranium from the partitioning, the accompaniment of 20 wt% U against the Pu weight is acceptable although the MA transmutation amount will be decreased slightly. For the rare earth (RE) from the partitioning, the accompaniment of 5 wt% RE against the MA weight is allowable. In the reprocessing, the decontamination factor, DF = 10 for RE is enough from the viewpoint of the neutronics design. The impact of the fuel composition accuracy is also investigated. The uncertainty of the ZrN ratio against the MA fuel should be less than 0.2% to minimize a surplus proton beam current due to the uncertainty. Through these investigations, the required conditions for the impurities in the partitioning, the MA fuel fabrication and the reprocessing processes were clarified from the viewpoint of the ADS neutronics design.