Development of simple method to incorporate out-of-core cooling effect on thorium conversion in multi-pass fueled reactor and investigation on characteristics of the effect

In addition, the characteristics of out-of-core cooling effect for the thorium conversion are evaluated for thorium fueled reactors MSBR and PBMR. It is concluded that the out-of-core cooling effect is suitable for MSBR to enhance thorium conversion because of the fast flow rate of fuel salt. On the other hand, the effect is neither important nor realistic to employ for PBMR because the in-core residence time of approximately 100 days is longer than the half-life of 233Pa of 27.0 days, and the effect cannot improve the conversion ratio significantly.