Optimization study of high conversion light water reactor with axially heterogeneous core

A concept of axially heterogeneous core type high conversion light water reactor (HCLWR) has been developed by extending the double flat core HCLWR concept. The core parameters of this heterogeneous core were optimized based on the knowledge that has been obtained in the studies of HCLWRs. As a result of the optimization, the core characteristics of the discharge burnup of 45GWd/t and the fissile Pu conservation ratio of 0.85 were obtained maintaining the void reactivity negative. The sharp power peaking, which appears at the boundaries of the active core and inner blanket regions, was pointed out to be one of the power peaking can be decreased by mixing Gd poison in the blanket region adjacent to the active core region. The use of Gd poison can also improved core burnup characteristics. (author)