Method and a device for control of the coolant flow in the fuel assembly of a pressurized water reactor

摘要

A method and a device for controlling the coolant flow to the fuel rods (1) in the fuel assembly of a pressurized-water reactor, fuel assembly including an elongated bundle of control rod guide tubes and fuel rods (1) which is arranged between a top nozzle and a bottom nozzle. The bundle is retained by spacers (2) supported by the control rod guide tubes and the top and bottom nozzles are provided with a plurality of openings for the coolant flow. According to the invention, the coolant flow along the fuel rods (1) of a fuel assembly which is under low load is reduced by the insertion of special, or the activation of existing, throttle or guide members (10,11,12,13,16) on the spacers (2) or on the fuel rods (1) between the spacers (2) such that the coolant flow is diverted to one or more adjacent fuel assemblies.