Utility of Including Passive Neutron Albedo Reactivity in an Integrated NDA System for Encapsulation Safeguards

Abstract: In August of 2017, the International Atomic Energy Agency (IAEA) issued the “Application of Safeguards to Geological Repositories (ASTOR) Report on Technologies Potentially Useful for Safeguarding Geological Repositories.” In this IAEA report, the nuclear safeguards experts convened made recommendations on var ious aspects of encapsulation facility and repository safeguards. Specific to the non-destructive assay (NDA) requirements, the ASTOR experts made six specific recommendations. To satisfy these recommendations, a team working under the direction of the Finnish Radiation and Safety Authority researched the capability of an integrated NDA system that combines the capabilities of a Passive Gamma Emission Tomography (PGET) instrument, a Passive Neutron Albedo Reactivity (PNAR) instrument and a load cell. The current study focuses a conceptual design of the PNAR instrument capable of supporting several of the IAEA recommendations. To enable this research goal, the performance of a PNAR instrument, designed to measure boiling water reactor assemblies, was simulated using fuel with the isotopic content representative of fuel of various initial enrichments, burnups and cooling times. The research results illustrate the capability of the PNAR instrument to fulfil the IAEA recommendations while using robust, relatively simple, hardware