REACTOR STRUCTURE OF FAST BREEDER REACTOR

PROBLEM TO BE SOLVED: To improve the thermal efficiency by raising the reactor outlet temperature and make a cooling components compact by widening the temperature difference between the inlet and the outlet of a reactor. SOLUTION: In the reactor structure of a fast breeder reactor containing the core 1 in a core bath 3 placed in a reactor vessel and letting coolant to pass, a hot plenum 9 formed on a reactor upper structure 8 collecting only coolant flowing out of high temperature assemblies in the core middle and outlet piping 11 connecting to a cooling loop by way of the hot plenum 9 and an upper lid 2 and for letting the coolant in the hot plenum flow out, are provided.