Year
1989
Abstract
Our experience with mixed oxide (MOX) fuel fabrication facilities leads us to conclude that there is inadequate guidance available to plant and process designers to make materials accounting systems timely, efficient, and minimally intrusive. A well designed state system for accounting and control of nuclear materials would be beneficial to plant operations and verification by the International Atomic Energy Agency (IAEA) or state regulatory agencies. Among the difficult accounting problems that arise in a large-scale MOX facility are the following: (1) process steps (such as the blending and splitting of powders) that require the accounting system to track material flow, calculate quantities based on previous measurements, and propagate uncertainties as part of data analysis; (2) extensive buffer storage areas involving long residence times that necessitate frequent corrections for material loss from radioactive decay; and (3) facility accounting at one level (for example, fuel pins) that must be reconciled with verification measurements at another level (for example, pin trays or assemblies). Approaches to addressing these problems include designing a special facility, simulating material flow, developing software for near-real-time materials accounting, and establishing achievable verification goals. This paper elaborates on these problems and proposes approaches to a materials accounting system design that considers facility, state, and IAEA safeguards and verification objectives.