Approach to IAEA material-balance verification with intermittent inspection at the Portsmouth Gas Centrifuge Enrichment Plant

Abstract

This paper describes a potential approach by which the International Atomic Energy Agency (IAEA) might verify the nuclear-material balance at the Portsmouth Gas Centrifuge Enrichment Plant (GCEP) for the circumstance in which the IAEA inspections occur on an intermittent basis. The verification approach is a variation of the standard IAEA attributes/variables measurement-verification method. This alternative approach is useful and applicable at the Portsmouth GCEP, which will ship all its product and tails UF/sub 6/ to United States facilities not eligible for IAEA safeguards. The paper reviews some of the relevant results of the Hexapartite Safeguards Project (HSP), describes the standard IAEA material-balance-verification approach for bulk-handling facilities, and provides the procedures to be followed in handling and processing UF/sub 6/ cylinders at the Portsmouth GCEP. The paper then discusses the assumptions made in the approach, and derives a formula for the probability with which the IAEA could detect the diversion of a significant quantity of uranium (75 kg of U-235 in depleted, normal, and low-enriched uranium) if this method were applied. The paper also provides numerical examples of IAEA detection probability should the operator divert uranium from the feed, product, or tails streams for the Portsmouth GCEP with a capacity of 1100 tonnes of separative work per year.