NON-CRITICALITY MEASURING DEVICE FOR SPENT FUEL ASSEMBLY

摘要

PURPOSE:To make the detection efficiency of a detector following variation of burnup degree of a spent fuel assembly as constant value and to precisely measure non-criticality of the spent fuel assembly having various burnup degrees. CONSTITUTION:This measuring device is provided with a neutron detector 15 devised to make fission neutron distribution in the horizontal direction of a spent fuel assembly 13 and inside neutron distribution in the same distribution by way of storing the spent fuel assembly 13 in a container covered with a gray absorbing body 12 in dry environment and to measure a second axial direction specified position neutron counting rate by way of approaching the device and a computing means 16 to compute assembly neutron effective multiplication constant by way of inputting the second axial direction specified position neutron counting rate, a previously gained first axial direction specified position neutron counting rate and assembly neutron source strength.