Calculation method of effective multiplication factor of subcritical neutron multiplication system and storage method in subcritical neutron multiplication system

摘要

PROBLEM TO BE SOLVED: To obtain a method for storage in which the evaluation value of the effective multiplication factor is always on a safety side of criticality safety control.SOLUTION: According to an embodiment, a method for storage in subcritical neutron multiplication system includes: a nuclear fuel composition calculation step for calculating fuel composition of an irradiated fuel on the basis of a specification of an unburnt fuel and combustion conditions; a system condition setting step for calculating a group constant and a neutron generation rate; a neutron flux measurement step for measuring a neutron flux of a subcritical neutron multiplication system; a neutron flux calculation step S110 for calculating a neutron flux; a correction step S132 and S141 for correcting the group constant or neutron generation rate so that the difference between the calculated neutron flux and the measured neutron flux is a prescribed reference value or lower; an effective multiplication factor calculation step S151 for calculating an effective multiplication factor; and a determination step S152 for determining whether or not the effective multiplication factor calculated in the effective multiplication factor calculation step is within a prescribed limit value, and conducting additional storage in the case of within the limit value while completing the storage in the case of not within the limit value.