DUCTLESS FUEL ASSEMBLY AND DUCTLESS REACTOR CORE OF FAST REACTOR

摘要

PROBLEM TO BE SOLVED: To make easily detectable an abnormality of a fuel assembly, and to improve the safety of a fast reactor by providing a duct for surrounding the upper part of a driver fuel region, and a fluid resistance element for giving resistance to a flow in the circumferential direction of the reactor of a cooling material. SOLUTION: In the ductless fuel assembly 1 of a fast reactor, for example, the outer periphery being limited to an upper region from the upper end of a driver fuel region 8 is surrounded by a duct 4 with a hexagonal hollow section. No duct exists around the fuel region 8, thus preventing neutron utilization efficiency from being reduced. Also, in a blanket fuel assembly being loaded at the periphery part of a reactor core or the fuel assembly 1 adjacent to a shielding body 2 in a diameter direction, a tie rod 14 where a fluid resistance element with a slender plate shape and specific structure is mounted is provided, thus preventing the mixing of a cooling material 10 at the upper part of the fuel assembly 1, improving the detection property of local clogging in the fuel assembly 1, and at the same time, preventing the run-off of the cooling material 10 to the outside that causes overheating.