Nuclear reactor protection device

Purpose: To enable to scram a nuclear reactor in a short period of time even when all of internal pumps are tripped. Constitution: A nuclear reactor power judging section compares a nuclear reactor output signal with a reactor output judging value and, if the level of the former exceeds the level of the latter, outputs a first signal indicating that the output is higher than the nuclear reactor output judging level. A reactor flow rate judging section compare a reactor core flow rate signal with a reactor core flow rate abnormal judging value and, if the level of the former is lower than that of the latter, outputs a second signal indicating that the reactor flow rate is lower. When both of the first signal and the second signal are inputted, an AND circuit outputs a reactor core flow rate abrupt change scram signal. The signal is inputted to a pilot solenoid valve for reactor scram. (Yoshino, Y.)