Abstract
The molten-salt reactor operated with thorium-uranium fuel-cycle can efficiently use Th resource, the reserves of which are abundant on the earth. However, the reactor needs 233U as fissile material, which does not exist in nature, and thus, a certain amount of 233U must be prepared before the reactor operation starts. One approach to produce 233U using BWR is proposed in this paper. The burn-up characteristics of ABWR of 1.35 GWe are calculated using SRAC2006 (nuclear analysis code) and JENDL3.3 (nuclear data file). The ABWR is loaded with Th as fertile material and Pu obtained from spent fuel discharged at 33 GWd/t out of BWR. On the basis of numerical analysis, the following results have been obtained. (1) ABWR using Pu in once through can produce 1.5 t of 233U in 4.2 years. The amount is enough to start-up the 200 MWe fuel self-sustaining molten-salt reactor (FUJI-U3). Fissile plutonium (Puf) supplied to the ABWR in this period is 6.57 t. (2) ABWR using not only Pu but also enriched uranium in multi-recycling can start-up FUJI-U3 in 3.1 years. In this case, we can reduce Puf to 4.94 t, but we must supply 0.39 t of fissile uranium. (3) ABWR using only Pu in fuel assemblies composed of 56 fuel pins or 44 fuel pins in multi-recycling can start-up FUJI-U3 in 3.1 years. In this case, we can reduce Puf to 4.93 t, but we must decrease the output power of ABWR to 97.8% of the rated power.
