Studies on the nondestructive gamma-ray spectrometry of irradiated nuclear fuels from power reactors

The gamma-ray intensities of irradiated fuels are nondestructively measured at a reactor site by using a gamma-ray collimator and a Ge detector system. However, there are some difficulties to keep the geometrical arrangement unchanged over a series of the measurement and to calibrate the gamma-ray intensities with absolute values. In order to avoid these disadvantages, an activity ratio measurement has been proposed and continued to be developed. Since 1972, gamma-ray spectrometry of irradiated fuels discharged from power reactors has been carried out in Japan Atomic Energy Research Institute. The purpose of the studies was to examine the applicability of the activity ratio measurement of fission products to evaluate the burnup and related parameters. The present paper summarizes the results of the studies