OPERATION METHOD OF INITIAL LOADING CORE

摘要

PROBLEM TO BE SOLVED: To provide an operation method of an initial loading core in which a sufficient reactor shut-down margin can be secured by preventing excess reactivity in a second cycle from being excessive without reducing the excess reactivity in a first cycle.

SOLUTION: A predetermined number of high concentration fuel out of the initial loading fuel such that the maximum value of the excess reactivity during the second cycle becomes equal to or more than the initial excess reactivity of the second cycle after completion of the first cycle and the reactor shut down margin during the second cycle becomes equal to or more than the minimum value of the reactor shut-down margin when the fuel replacement is not performed after the first cycle is replaced with replacement fuel having gadolinia concentration which is higher than that of the high concentration fuel after combustion of the first cycle.

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