Nuclear & Atomic Data Needs for NDA Measurements in Nuclear Safeguards

International Nuclear Safeguards and Nuclear Material Accounting and Control (NMAC) rest on accurate physical inventory measurements. For instance, the commercial nuclear fuel cycle requires the verification of material in a variety of forms under a diverse set of measurement conditions, and to perform these measurements the nuclear safeguards inspectorates employ a wide suite of nondestructive assay (NDA) techniques and instruments. NDA methods based on passive gamma spectroscopy, passive and active neutron correlation counting, nuclear calorimetry, and x-ray fluorescence techniques are perhaps best known and most widely established, but a number of techniques are under development to meet emerging difficult to measure items and material flows. A common feature for all NDA techniques is their dependence from implementation to analysis and interpretation on atomic and nuclear data. A physical model supported by data may be used to justify technique selection. Scientific design and optimization of measurement systems using forward prediction models rest on the quality of physical data. Basic data is often also needed during the characterization and calibration of instruments. During NDA analyses, correction factors and interference corrections typically require basic data as does the inversion of the measurement data collected into quantitative assay results and the interpretation of the nuclear material source term. Historically, nuclear safeguards measurement applications have relied on atomic and nuclear data measured and evaluated for other purposes. In this paper, we highlight the central importance of obtaining and evaluating nuclear data to support NDA measurements for international nuclear safeguards. We emphasize where data improvements are required for enhanced safeguards science and applications.