Demonstration irradiation of MOX fuel in Mihama unit-1

In spent LWR fuel, the nuclear fission substances which can be used again are contained, for example U-235 remaining without causing nuclear fission and Pu-239 and Pu-241 formed from U-238. It is important to effectively utilize them for saving natural resources, and it is one of the subjects in atomic energy development. In the long term plan of atomic energy development and utilization in 1987, plutonium is basically used for fast breeder reactors, and in order to establish plutonium utilization technology, it was decided to realize plutonium utilization with light water reactors and advanced thermal reactors. First, as the demonstration irradiation project with a small number of fuel assemblies, four fuel assemblies of uranium-plutonium mixed oxide fuel (Mox fuel) were charged in No. 1 plant of Mihama Power Station, Kansai Electric Power Co., Inc. in March, 1988 to confirm their characteristics. In this paper, the comparison of the measured values and the design values of power distribution in the core and the verification that the nuclear design techniques for PWRs can be applied to MOX fuel are reported. The design of MOX fuel assemblies, the comparison of the measured values and the design values of core physics in 7th cycle and so on are described. (K.I.)