Method of measuring the reactor core flow rate

Purpose: To uni-meaningly determining the reactor core flow rate in BWR type reactors by measuring the differential pressure in the liquid phase portion. Method: In the conventional method of measuring the coolant flow rate in the reactor core, back flow is resulted if one of recycling pumps is stopped or, in the method of measuring the differential pressure for the reactor core support plates, the pressure loss is varied depending on the amount of voids. Accordingly, the flow rate can not be determined uni-meaningly. In view of the above, a coolant channel is formed at a lower plenum portion below the reactor core support plate and above the upper end of the shroud leg, and a reactor core flow rate measuring plate is disposed such that a differential pressure is generated due to the passage of the reactor core coolants. The flow rate can be determined by measuring the differential pressure of the measuring plate. In this way, it is possible to reliably measure the flow rate of the reactor core coolants and the reactor core flow rate can be measured even in the case where one of the plurality pumps is stopped. (Kawakami, Y.)