Review of Nondestructive Assay Methods for Safeguards Monitoring and Verification

Efficient and accurate verification techniques are necessary for a functional nonproliferation framework. Passive, nondestructive assay (NDA) methods are often more convenient but are limited to the inherent physical characteristics of the material, such as emitted radiation, to confirm the composition and amount of fissionable material present. Existing NDA instrumentation and methodologies are summarized in the context of specific materials and radiological signatures of interest to the International Atomic Energy Agency’s (IAEA’s) safeguarding framework. Additionally, a discussion and analysis of these NDA capabilities will highlight an ultra-high-resolution gamma microcalorimeter spectrometer. This microcalorimeter is an advanced, up-and-coming NDA technology with the potential to significantly improve the precision, accuracy, and confidence in safeguards NDA measurements. Technical details of this instrument are provided, along with results showcasing the capabilities of gamma microcalorimetry for nuclear material measurements.