PURPOSE: To provide a core supporting structure for fast breeder reactor in which the fuel assembly is restrained from floating when it is pushed up abruptly by vertical seismic force.
CONSTITUTION: The core supporting structure comprises an upper fitting part 9 formed by the inner face part of an upper support piece 11 bonded to a coupling pipe 1 and the upper end part of an entrance nozzle 4, and an intermediate fitting part 15 formed by the intermediate part of the entrance nozzle 4 and the intermediate part of the coupling pipe 1. A lower supporting part 12 having enlarged fitting cross-section is provided at the lower fitting part of the entrance nozzle 4 and the coupling pipe 1 with the radial gap on the lower fitting face at the fitting part being set at 0.1mm and a low pressure plenum communication hole 7 having large cross-sectional area is made at an axial intermediate position of the lower supporting part 12. It is thereby separated into upper and lower fitting faces 13, 14 and the lower fitting face constitutes an enclosed space.
OHASHI MASAHISA
HORIUCHI TOSHIHIKO
