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The U.S. Department of Energy’s Next Generation Safe­guards Initiative Spent Fuel (NGSI‑SF) project is nearing the final phase of developing several advanced nondestructive assay (NDA) instruments designed to measure spent nucle­ar fuel assemblies for the purpose of improving nuclear safeguards. Current efforts are focusing on calibrating sev­eral of these instruments with spent fuel assemblies at two international spent fuel facilities. Modelling and simulation is expected to play an important role in predicting nuclide compositions, neutron and gamma source terms, and in­strument responses in order to inform the instrument cali­bration procedures. As part of NGSI‑SF project, this work was carried out to assess the impacts of uncertainties in the nuclear data used in the calculations of spent fuel con­tent, radiation emissions and instrument responses.

Nuclear data is an essential part of nuclear fuel burnup and decay codes and nuclear transport codes. Such codes are routinely used for analysis of spent fuel and NDA safe­guards instruments. Hence, the uncertainties existing in the nuclear data used in these codes affect the accuracies of such analysis. In addition, nuclear data uncertainties repre­sent the limiting (smallest) uncertainties that can be expect­ed from nuclear code predictions, and therefore define the highest attainable accuracy of the NDA instrument. This work studies the impacts of nuclear data uncertainties on calculated spent fuel nuclide inventories and the associated NDA instrument response. Recently developed methods within the SCALE code system are applied in this study. The Californium Interrogation with Prompt Neutron instru­ment was selected to illustrate the impact of these uncer­tainties on NDA instrument response.