Control rod withdrawal monitoring system

Purpose: To improve the responsivity of a control rod withdrawal monitoring system by judging the number of bypassed local power range monitors (LPRM) and amplifying the average value of the signals from the monitors based on the judged results in BWR type reactors. Constitution: The number of bypassed LPRM is judged by a bypass number judging circuit, and output signals from an averaging circuit that averages the signals from LPRM are amplified by a signal correction circuit. Thus, the output from the averaging circuit are amplified by so much in the signal correction circuit as the number of the bypassed LPRM increases. Degradation in the responsivity due to the bypassing of LPRM can thus be prevented, whereby erroneous withdrawal of the control rods, if should occur, during power operation can be inhibited always at an early position to prevent the powerup. (Moriyama, K.)