CHARACTERIZATION OF THE PERFORMANCES OF C/S DEVICES AND SYSTEMS

Over the past few years the IAEA have shown a need to place increasing reliance on C/S techniques. The need arises frcm several causes, for example: a growth in the number of facilities placed under safeguards; the introduction of new processes and storage facilities where materials may be inaccessible for measurement purposes; facilities which contain large quantities of material, the verification of which could require large resources. Consequently, there have been discussions within the Agency directed towards the development of guidelines which might be used to decide whether material under C/S requires re-measurement or re-verification. The Agency is guided to some extent by the principles formulated by SAGSI that 'if C/S measures providing sufficient assurance against circumvention or defeat by any realistic means were available, re-measurement of material under such C/S would not be necessary1. Not surprisingly, 'sufficient1 is not defined but clearly there is a need to ensure that C/S devices and systems are capable of adequate performance and are deployed in sane optimal way. There is also a need for retrospective evaluation of the actual performance of the C/S regime. Consequently we believe that some formal structure is required against which C/S devices and systems can be compared and their relative performance assessed against defined functional objectives. In late 1988 an • Advisory Group Meeting (AGM) in the IAEA recommended that development should be encouraged of methodologies which might be capable of illustrating the performance capabilities of C/S. It was acknowledged by that Meeting that it would not be possible to express detection performance in a quantitative way comparable to the accountancy detection criteria. It was the view of the Meeting that it should be possible to structure the quantitative and qualitative performance characteristics of C/S devices and systems in a way which could permit comparative evaluation to be made of alternative devices and systems judged against defined safeguards functions. As a consequence of that AGM an 'expert group' (EG) met in Vienna In October 1989 to review sane proposed methodologies and to pursue them 'to the extent that their feasibility and potential value can be demonstrated in relation to safeguards'. Two basic methodologies were considered by the EG; one put forward by the Agency (Yellin and Rundquist) and one by F.J. Walford (1)