Reactor protection device

Purpose: To previously inform the possibility of channel oscillations based on the signals from neutron detectors to a reactor operator, as well as inhibit the control rod extraction when it approaches the critical point for the channel oscillations due to the rod extraction in the protection device for a BWR type reactor. Constitution: When a selection circuit judges that the state of a nuclear reactor is within the range of the performance of a protection device, a decision circuit selects a detector with the maximum output based on each of the signals from neutron detectors. The detection outputs signal thus selected is inputted to an output distortion coefficient calculation circuit and the output distortion coefficient thus calculated is supplied to a comparison circuit and, if it is greater than the set signal, causes a display to flicker. Furthermore, if the output distortion coefficient is in excess of another set signal greater than the above set signal, a control rod extraction inhibition signal is sent out from the comparison circuit. (Horiuchi, T.)