Design and validation of a gamma-ray scanning system for measuring irradiated nuclear fuel

A prototype gamma-ray scanning system was designed to perform post-irradiation examination measurements of nuclear fuel. The is composed a coaxial high-purity germanium (HPGe) detector, collimator, and mechanical positioning stages that translate the fuel sample across front collimator. This paper documents design process, modeling laboratory characterization performed validate system. done using Monte Carlo N-Particle code with vendor-supplied specifications, dimensional measurements, X-ray radiographs HPGe detector. included calibrated radiation sources in different geometries, calculations for absolute efficiency dead time. Benchmark were by an irradiated rodlet containing ten pellets 4.9% enriched UO2 zirconium alloy. These results compared simulated spectra further help characterize detector model. One goal determine number fissions per gram fuel; comparison from this system's assay are agreement previously estimated results.