How useful can Probability Risk Assessment tools be for Proliferation Resistance assessment

Abstract

This paper is aiming at discussing the possible use of tools developed in nuclear safety assessment in the field of proliferation resistance. Proliferation Resistance is defined as those characteristics of a nuclear energy system that impede the diversion or undeclared production of nuclear material, or misuse of technology by States in order to acquire nuclear weapons. These characteristics encompass both technical (“intrinsic”) features as well as institutional (“extrinsic”) measures such as international treaties, verification schemes or export controls. In the initiatives to develop innovative nuclear energy system (America-led Generation 4 International Forum, IAEA’s INPRO project,.), proliferation resistance is one of the key elements, along with economics, safety, sustainability and environment which is to be addressed. Assessment of proliferation resistance is therefore of timely importance.

Proliferation Resistance design and assessment is calling for the use of the principle of defence in depth. This concept is widely and successfully used in nuclear safety. Proliferation Resistance assessment enters in the category of system analysis. Having this in mind — system analysis, and proposed application of safety concept to proliferation resistance — there is a clear rationale to examine how other tools developed for the safety analysis of complex systems can prove valuable for the design and performance analysis of proliferation resistance. In the field of nuclear safety, Probability Safety Assessment (PSA) brought a totally new approach which has proven a very useful complement to the deterministic approach. In the same way, in the field of proliferation resistance, we believe that Probability Risk Assessment (PRA) can be a valuable complement to the attribute methodology.

So far Probability Safety Assessment in nuclear safety has been used to improve a reactor design (there is no example of using PSA to compare directly different concepts of reactors). We would therefore focus the use of Probability Risk Assessment in Proliferation Resistance in the same line. In this respect, some current limitations shall be recognised, such as the lack of extensive data base to perform the quantitative analysis and the corresponding need to rely on expert judgement at the root of the analysis. That being said, PRA has a high potential to be an effective tool. As an example, a fault tree type / scenario type of analysis will bring value in highlighting the strength and weakness of a given nuclear system or of a given facility (reactor, fuel cycle facility, etc..) and give indication to the designer on the way forward to further improve the overall intrinsic and extrinsic coverage of a given proliferation path.

This paper offers a first developed framework to derive a practical and effective use of proven nuclear safety analysis tools to the needs and specificities of proliferation resistance assessment.