| 摘要 |
PROBLEM TO BE SOLVED: To avoid a wrong reactor scram by providing the logic for switching to an intermediate area if both conditions of the neutron flux obtained by the Cambel method and the count rate are valid. SOLUTION: The logic for switching 5 from a neutron source area to an intermediate area has a condition for switching 5 to the intermediate area so that a value in the Cambel method can be adopted from among the values (for example, >3×10<8> nV) of neutron flux 4 by a measurement counting rate in a pulse countering method. The logic also has a condition in which the measurement in the pulse counting method switches 5 to the intermediate area even in the count rate 6 (>10<-6> cps). Moreover, switchover logic is also provided which switches 5 to the intermediate area when an AND condition is valid from the value (for example, 3×10nV) of the neutrons 7 found in the Cambel method regardless of the count rate value and the counting rate 8 (>5×105cps). Even though such an AND condition raises the reading found in the Cambel method which is not accompanied by the increase of the count rate in the neutron source area, the switchover does not occur and a wrong reactor scram can be avoided.
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