Reactor failure detecting device

Purpose: To provide the subject device of high practical utilization wherein the waveform of the temperature fluctuation signal is fixed by the self-regression model, and error signal between the temperature flucturation signal to be monitored and the temperature fluctuation signal estimated from the self-regression model is sought, and the self correlative function is monitored. Constitution: A signal generated from a temperature detector is applied to a failure detection computation treating device through and AC amplifier and a low-pass filter. The failure detection computation processing device fixes the self-regression model of the temperature fluctuation signal and calculates the estimated value of the temperature fluctuation signal by use of the fixed self-regression model, the error signal between the temperature fluctuation signal and the estimated value is calculated to obtain the self-correlative function of error signal, and the value of the self-correlative function is compared with the alarm limit value, thereby to detect the failure generated in the fuel assembly. (Yoshihara, H.)