Nondestructive Assay Measurement Traceability: The Burden of Proof

The desire for improved nuclear materials safeguards, including considerations of real time measurement and control capability, has been the driving force for many recent developments in the area of nuclear fuel cycle measurements. This emphasis has already effected operating requirements for the control of special nuclear materials in domestic fuel fabrication and reprocessing facilities. Typical effects have included: a. Improved measurement capability b. Increased utilization of available technology c. Increasingly detailed and rigorous regulations As a result of these and other incentives, nondestructive assay methods have emerged as a practical possible approach for satisfying numerous special nuclear materials measurement requirements. Particular advantage has been shown where materials to be measured are difficult to sample (e.g., heterogeneous), or where prompt measurements are required to satisfy process control, safety or safeguards considerations. This paper reviews the underlying factors which contribute to successful nondestructive assay safeguards measurement applications and relates performance requirements, as defined for licensee facilities in recent Nuclear Regulatory Commission (NRC) regulations, with current capabilities. The need to complete the development cycle associated with currently available nondestructive assay technology to include mechanisms for establishing measurement traceability is discussed. The achievement of such traceability is identified as a cardinal prerequisite to the satisfaction of recently issued NRC measurement control regulations for all safeguards measurements. Alternative solutions to the nondestructive assay traceability problem are reviewed and evaluated, including two primary approaches: (1) independently supplied standards, and (2) standards comparison programs. It is suggested that any cost effective allocation of near term NRC development resources should address the traceability aspects of nondestructive assay methods at the expense of developing or demonstrating additional measurement techniques or hardware. Without such efforts, the usefulness of available nondestructive assay technology, as a tool for satisfying current licensee safeguards regulatory requirements, is considered to be seriously restricted.