METHOD FOR MEASURING RELATIVE DISTRIBUTION OF SPECIFIC BURNUP, DEVICE FOR MEASURING RELATIVE DISTRIBUTION OF SPECIFIC BURNUP, DEVICE FOR MEASURING RADIATION SIGNAL DISTRIBUTION AND PROGRAM FOR MEASURING RELATIVE DISTRIBUTION OF SPECIFIC BURNUP

摘要

An upper detector (2) and a lower detector (3) both facing at least the side face A of a fuel assembly (1) irradiated with neutrons in a reactor and detecting radiation are arranged at a predetermined interval in the axial direction of the fuel assembly (1). While moving the fuel assembly and the upper and lower detectors relatively along the axial direction of the fuel assembly, distribution of radiation signals is measured by the upper and lower detectors and the pieces of radiation signal distribution measured by the upper and lower detectors while multiplexing the data of the same portion of the fuel assembly in the axial direction are compared thus judging soundness of the radiation signals measured by the upper and lower detectors for each measurement. Subsequently, relative distribution of burnup is measured by calculating relative burnup using the radiation signals thus measured. With such an arrangement, relative distribution of specific burnup of the fuel assembly can be measured while ensuring reliability of measurement.