Present Status of Reactor Physics Research Activities Related to Very High Temperature Reactor in Japan

Reactor ghysics research activities in Japan related to Very High Temperature Reactor (VHTR) for multipurpose usage are briefly summarized. Neutronic core design accuracy required for the experimental VHTR is made clear at first, and description is given on the nuclear data compilation and the neutronic calculation code development. For experimental works, after a review on the results of the reactor physics experiments ever done an SHE (Semi-Homogeneous Experiment) at Japan Atomic Energy Research Institute, reconstruction program of the critical assembly is presented aiming at performing a detailed mock-up experiment of the experimental VHTR loaded with low enriched uranium coated particle fuels. At last, improvement of the neutronic calculational accuracy attained through comparison between calculation and experiment is illustrated and some future problems are point out.