| 摘要 |
PROBLEM TO BE SOLVED: To provide a subcriticality measuring method and device capable of evaluating subcriticality in a wide range from subcriticality to criticality with high precision.SOLUTION: The device obtains a corrected inverse count rate ratio which is an inverse count rate ratio &phgr;/&phgr; which is a ratio of a detector output &phgr;of a neutron detector in a standard core state to a detector output &phgr; of the neutron detector in a core state prior to bringing the core to criticality which is different from the standard core state, corrected by a correction coefficient; calculates predicted subcriticality in the core state where the corrected inverse count rate ratio is obtained, by reactor core analysis with the use of a reactor core analysis model; modifies a control rod position or boron concentration, thereby obtaining a relational expression between an inverse count rate ratio obtained in the process of modification of the control rod position or boron concentration and the predicted subcriticality by taking into consideration a measured value of boron concentration at the time of the modification of the boron concentration and a calculation error at the time of the modification of the control rod position; and evaluates subcriticality with the use of the relational expression. |
