Power control device for BWR type reactor

The power control device for a BWR type reactor according to this invention can prevent power change and keep stable operation state when abnormality such as load interruption of electric generator or turbine trip, etc. occurs. That is, the power control device comprises a recycling pump for compalsorily circulating reactor coolants to control the reactor core power, a detector for detecting the open/close state of turbine main steam check valve and a speed limiter for outputting a run-back signal for decelerating the recycling pump to the lowest allowable flow rate upon receiving the valve closure signal from the detector. With such a constitution, if abnormality such as load interruption of electric generator or turbine trip should occur to rapidly close the turbine main steam check valve, the abnormality is detected and the recycling pump is decelerated to a predetermined number of rotation. As a result, the reactor core power is controlled. The reactor core flow rate corresponding to the number of rotation is greater than the spontaneous recycling flow rate. (I.S.)