Advances in the Measurement Sciences for Verification Being Undertaken at LANL in Support of Nuclear Safeguards

The objective of international nuclear safeguards is the timely detectionof the diversion of nuclear materials in peaceful nuclearprograms for use in nuclear weapons or other explosive devices.In safeguarding nuclear materials, design information verificationof facilities, establishment of a materials control and accountancy(MC&A) system, the implementation of a containment andsurveillance system, along with an inspection regime are of fundamentalimportance to creating overall confidence in a nation’sadherence to its international obligations. The MC&A activity issupported by nondestructive physical measurements. Los AlamosNational Laboratory (LANL) has been at the forefront of researchand development in nondestructive measurement techniques foridentifying and quantifying key attributes of nuclear materialssince the field of measurement sciences for verification began.Nondestructive assay (NDA) entails quantifying some attributeof nuclear material—such as enrichment, relative isotopic composition,or mass—using penetrating signatures so that the itemcan be measured intact with minimal or no preparation. In thispaper, we review some of the work currently ongoing at LANL.Most of the examples we provide involve measuring neutrons,photons, or heat naturally emitted by the items under study. Weconclude with thoughts on emerging challenges and opportunitiessuch as the need for improvements in basic nuclear data.