Development of threshold energy comprehensive neutron analysis method for 3S with DD neutron source

The integration of nuclear safety, security, and safeguards (3S) is particularly important for innovative advanced nuclear power systems that use HALEU (High-Assay Low-Enriched Uranium). To ensure that 3S requirements are fully met, the authors developed an analysis method that simultaneously enables criticality monitoring, nuclear material theft detection, and nuclear material accountancy. However, the applicability of the developed method to nuclear material accountancy is limited because it depends on the precision of the Rossi-alpha method, which cannot be used for systems with excessively deep subcriticality. To address this issue, a new method that expands the scope of application by leveraging the characteristics of the DD neutron source has been developed and discussed in this study. A series of experiments was conducted to validate the effectiveness of these new methods using HALEU samples and a DD neutron source at the KUCA facility. As a result, the effectiveness of the new methods was confirmed.