Assessing Instrument Performance for Passive Gamma Emission Tomography of Spent Fuel

Validation of spent nuclear fuel at the single pin level is a challenging technical problem. Passive Gamma Emission Tomography (PGET) uses an array of highly collimated detectors to measure an angularly-sensitive map of gamma emissions and reconstruct into a cross-sectional emission map, and has been of interest for verification of spent fuel assemblies. Following multiple years of collaborative research supported by many state support programs, the first tomographic instrument was recently authorized by the IAEA for use in verification of spent nuclear fuel assemblies. For spent nuclear fuel assemblies, the PGET instrument has been demonstrated to provide sensitivity approaching the level of single pins on a variety of assemblies of different types and cooling times. Development of the instrument has been supported by a modeling and analysis framework designed to provide model-based assessments of system performance. We describe that framework, including a process to benchmark radiation transport models against measured PGET data, generation of synthetic tomography datasets with specific fuel properties and statistical variations, detector response calculations, and finally a statistical analysis across an ensemble of synthetic datasets to provide predictive estimates of PGET performance.