Nondestructive Quantitative Analysis of Difficult-to-Measure Radionuclides 107pd and 99Tc.

Considering the expanding demand for nuclear waste management of the spent nuclear fuel materials in near future, a nondestructive analytical scheme applicable to one of the most difficult-to-measure nuclides Pd-107, which emits no decay gamma-rays and whose half-life is too long to be decayed out during a human lifetime, was designed. The scheme consists of a sophisticated instrument capable of the detection of gamma-rays by Ge detectors coupled with time-of-flight measurement of neutrons and a high-intensity pulsed neutron beam and can simultaneously perform time-of-flight-coupled prompt gamma-ray analysis (TOF-PGA) as well as PGA and neutron resonance capture analysis (NRCA). The analytical capability for simulated samples of the Tc-platinum group metals (Tc-PGMs) obtained by the group-partitioning process of spent nuclear fuels, which contain not only Pd-107 but also Tc-99 and other difficult-to-measure fission products, was evaluated. It was confirmed that although PGA and NRCA can accurately analyze both nuclides in individual, single substances, only TOF-PGA can analyze Pd-107 as well as Tc-99 in the Tc-PGM-simulated sample. The TOF-PGA measurement technique can be widely used for the nondestructive analysis of Pd-107 and Tc-99 in nuclear wastes.