Decision-directed materials-accounting procedures: an overview

With materials balances taken at intervals, methods for treating materials balance data and their use by safeguards decision-making are relatively straightforward. The emphasis on accounting in which balances may be drawn on a daily or weekly basis, raises anew questions in these two areas: (1) what is the most effective means of extracting the maximum amount of information; and (2) how should safeguards decision-makers use the results, and what impact does the decision process have on the analysis techniques. These questions lead to considering combinations of materials balances, which exposes a whole new set of concerns. For example, we must select the most appropriate combinations, which implies some consideration of possible diversion scenarios, such as abrupt or protracted. Control of the overall false-alarm rate is an important requisite of the composite procedure. Significant work has been done on loss estimators, but their role in the materials accounting decision process has only begun to be examined. Current criteria may require periodic statements with respect to materials loss; the analysis procedures must be structured to provide such information. This paper presents an overview of the current technology. Questions still to be answered are pointed out.