An evaluation of safeguards approaches for neptunium

The International Atomic Energy Agency has recently drawn attention to the fact that neptunium (Np), a byproduct of the nuclear power industry, can be used to make nuclear weapons. Current monitoring approaches for Np do not rely on material balance accounting as is used for uranium and plutonium. I n tile future this may change. Although full material balance accounting is not anticipated for Np, it is informative to evaluate the impact and benef it of full material balance accounting when considering other options. Ther efore, this paper will apply systems analysis to evaluate ways to convert t he current system to full materials balance accounting that will minimize t he intrusiveness of the verification system and minimize costs to both the facility operator and the inspection agency. We then compare full material balance accounting to partial material balance accounting and to a ratio-mo nitoring technique referred to as flow sheet verification. We conclude that sampling approximately 25% of the batches is likely to be adequate and tha t Pu (or perhaps Cs-137) Will be the most effective surrogate for estimatin g the Np in the input accountability tank.