A Japanese gadolinia fuel usage and demonstration program

Kansai Electric in Japan has begun the large-scale commercial use of gadolinia-bearing fuel. In preparation for this implementation, gadolinia fuel assemblies were designed and licensed, and eight demonstration assemblies were irradiated in cooperation with the fuel vendors Nuclear Fuel Industries (NFI) and Mitsubishi Heavy Industries (MHI). This paper presents an overview of the gadolinia fuel design, the demonstration irradiation, and the postirradiation examination of eight fuel assemblies. Design studies showed that 6 wt% Gd2O3 in UO2 was the optimum in terms of reactivity control capability at the beginning of cycle, peaking factors, residual penalties, and usage experience. The loading of 8 gadolinia fuel assemblies into Mihama No. 1 (two-loop plant) and 32 gadolinia fuel assemblies into both Ohi No. 1 and No. 2 (four-loop plant) is scheduled this year, and more than 100 gadolinia fuel assemblies will be loaded next year. To extend cycle operation even further, a study of up to 10 wt% fuel has been initiated