“…To reduce the fuel cost and the amount of spent fuel per unit energy generation as well as improve the physical properties of fuel matrix, the mixed oxide fuel such as U 1-y Th y O 2 solid solution has been considered as an alternative to the conventional UO 2 fuel in the past few decades [1][2][3][4][5][6]. The reasons why the thorium containing fuels are possibly advantageous compared to pure UO 2 are the desirable properties of ThO 2 which include [7][8][9]: (1) the neutronic performance of ThO 2 is very excellent due to the high conversion ratio of the Th, (2) the thermal conductivity and melting temperature of ThO 2 fuel are higher than that of UO 2 fuel, (3) the amount of long-lived minor actinides and plutonium generated in the fuel cycle is small, and (4) the corrosion resistance of the ThO 2 fuel in the high-temperature water is very excellent.…”