EXTENSION OF FUEL CYCLE LIFE FOR REACTOR CORE

摘要

PURPOSE: To use a nuclear fuel more efficiently by limiting the burnup degree by inserting a power control rod into some one of highly reactive fuel assembly in a first period of a fuel cycle life, taking out the output control rod, increasing power allotment, and improving the reactivity in a second period. CONSTITUTION: In a nuclear reactor core, leakage of neutrons is minimized by arranging fuel assemblies with high reactivity in a pattern in which a most part of the fuel assemblies are positioned in the inside of the core circumference in an initial period of the fuel cycle life and the burnup degree in a first period of the fuel cycle life is limited by inserting a power control rod 21 into any of the fuel assemblies with high reactivity, the power allotment is increased by taking the power control rod 21 out of the fuel assembly of the fuel assemblies, so that the reactivity of the whole body of the core can be raised based on the power allotment effect due to the power increase and the low leakage effect. As a result, the fuel cycle life can be prolonged.