| 摘要 |
PROBLEM TO BE SOLVED: To avoid erroneous calibration due to the fluctuation of the inside of a reactor and contrive improvement of reliability of the calibration by judging sensitivity calibration to be unavailability when the fluctuation exceeding an allowable value by a fluctuation monitoring means. SOLUTION: An LPRM(Local Power Range Monitor) watching part 22 judges whether it is during heater calibration or not on the basis of the presence of a heater calibration signal, each LPRM output given from an isolation part 21 is read every same string, waited only for a constant time, and read again every same string. Thereafter, the LPRM watching part 22 judges whether the output fluctuation of each LPRM exceeds an allowable value (±α) or not every same string, and when the fluctuation does not exceed, judgement is performed on whether heater calibration is completed or not. In addition, as a result of judgement, when the fluctuation of each LPRM output exceeds the allowable value, the heater calibration is judged impossible, and a heater calibration impossibility signal is output to a gamma thermo-data processing part 23.
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