REACTOR

摘要

A reactor (2) is a pressurized water reactor which is provided, in a pressure vessel (2P), with a fuel portion (2C) constituted by combining a plurality of fuel assemblies each constituted by bundling a plurality of fuel rods filled with nuclear fuel, and a control rod (2L) for controlling nuclear reaction of the nuclear fuel. In the reactor (2), concentration of a neutron absorber contained in the primary coolant during rated output operation of the reactor (2) at the time of starting rated output operation is set equal to or smaller than a value obtained by adding a predetermined value to the value which is obtained by subtracting the concentration of the neutron absorber required for cold stopping the reactor (2) at the time of starting operation of the reactor (2) and maintaining the state from the concentration of the neutron absorber required for cold stopping the reactor (2) at the time of ending operation of the reactor (2) and maintaining the state.