Study on Burnup Characteristics of Actinide Burnable Poisons in Plate-Type Fuel Assembly

In order to study the burnup characteristics of actinide burnable poisons in plate-type fuel assembly and the feasibility of actinide burnable poisons in extending core lifetime, the burnable poison loading, burnup depth and utilization of 235U in plate-type fuel assemblies with different enrichments but same initial kinf were calculated and analyzed in this paper. The results show that, in the case of low enrichment (4%~7%), 240Pu burnable poison exhibits a good conversion effect during the lifetime, and the utilization of 235U is high, which plays a role in extending lifetime. In the case of medium enrichment (25%~40%), the conversion effect of the 240Pu burnable poison is weakened. The 231Pa burnable poison exhibits a better conversion effect during the lifetime. In the case of high enrichment (70%~97%), the assemblies containing 231Pa can achieve the deepest burnup and its utilization of 235U is also the highest, although the conversion effect of the 231Pa burnable poison is weakened. It can be concluded that, 240Pu can be used as the burnable poisons for the low enrichment fuel for long lifetime purpose. However, 231Pa is preferred for the circumstances of medium and high enrichment fuels.