A REVIEW OF INTERNATIONAL PROLIFERATION RISK ASSESSMENT METHODOLOGIES AND APPLICATION BY THE UK NATIONAL NUCLEAR LABORATORY

There are two major international projects concerned with advanced reactor development: the IAEA International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) [1] and Generation IV International Forum (GIF) [2]. In both these projects, promoting nuclear systems which are inherently resistant to weapons proliferation are key aspects and the development of Proliferation Resistance and Physical Protection (PRPP) assessment methodologies represents an important part of both projects. One aim of INPRO is therefore to develop an internationally agreed methodology for objective assessment of proliferation resistance. This is also one of the goals of GIF and to date the two projects have taken different approaches and are now collaborating with a view to developing complementary approaches [3]. The UK has several potential applications for PRPP methodologies relating to the assessment of preferred options for historic nuclear liabilities management and to the UK’s plans for a new build reactor fleet and the UK National Nuclear Laboratory (NNL) has developed its own methodology that is flexible enough to apply to all the applications that are envisaged. The NNL methodology has been developed to be deliberately very general such that it can be applied to different risk pathways, such as diversion of fissile material by a state and theft of radioactive material by a sub-national group. It can also be applied to assess the risk inherent in other fuel cycle activities, such as the geological disposal of plutonium waste forms. NNL’s approach is flexible and one implementation incorporates useful elements from the GIF methodology. This paper briefly surveys the international PRPP methodologies that have been developed, focusing on the INPRO and GIF methodologies, but also the many other approaches which have been proposed in the literature. The paper summarises NNL’s analysis of the strengths and weaknesses of the different approaches, which led to the development on NNL’s methodology. The paper then illustrates the usefulness of the approach by describing the results of an assessment carried out on behalf of the Nuclear Decommissioning Authority (NDA) in which a relative proliferation risk assessment was made for different options for managing the UK’s stock of separated plutoniu