Reactor monitoring device

Purpose: To enable judgement for the coolant level by the exact decision for the atmospheric temperature in the reactor core, so as to take countermeasures without delay upon loss-of-coolant accidents. Constitution: A composite detector for the detection of gamma-ray intensity and temperature is used as a detector, which is mounted to the reactor core through a guide pipe for a calibration neutron detector. On measuring the temperature by a thermocouple while driving the composite detector mounted in this way by way of a drive cable and along the inside of the guide pipe and calibrating the gamma heating on every predetermined point, the temperature for the atmosphere in the reactor core can be decided accurately to judge the coolant level. Accordingly, upon the loss-of-coolant accidents, countermeasures can be taken without delay. (Yoshihara, H.)