Pressure-loss adjusting member and reactor

摘要

[Problem to be Solved] To suppress problems due to a flow of a primary coolant while easily distributing a flow rate of the primary coolant to fuel assemblies. [Solution] A pressure-loss adjusting member 60 includes: a pressure-loss adjusting hole 62 that can cause light water to pass therethrough in a state with a pressure-loss being increased more than that of when light water flowing around the fuel assembly passes through only a core support plate flow hole formed in a lower core support plate; and a core support plate engaging unit 70 that can be engaged with the lower core support plate by being inserted into the core support plate flow hole. Accordingly, the flow rate of light water flowing toward the fuel assembly can be reduced by arranging the pressure-loss adjusting member 60 between a lower nozzle of a fuel assembly having a small pressure-loss and the lower core support plate, and rattling or the like of the pressure-loss adjusting member 60 can be suppressed by engaging the core support plate engaging unit 70 with the lower core support plate. As a result, problems due to the flow of light water can be suppressed, while easily distributing the flow rate of light water to the fuel assemblies.