Towards a Holistic Risk Management Strategy or Long-Term Interim Storage

Abstract

Long-term surface storage of intermediate-level radioactive waste (ILW) has become an important issue for regulators and site operators in the UK following deferral of the Nirex deep repository for the disposal of ILW, and the resulting hiatus in Government policy. This paper identifies some key life-cycle issues associated with interim safe storage (ISS) of ILW, and also some of the key features of existing stores. Important risk management issues include store design and environmental controls, conditioning and packaging, package handling and cranes, operation, monitoring of waste packages, package retrieval, external environmental factors, stakeholder issues and costs. All of these issues will need to be addressed during the design, construction and operation of an ILW store. Given the wide and diverse range of issues requiring consideration, it may be difficult to choose between alternative design concepts or risk management strategies. We demonstrate a multi-criteria decision analysis approach to ILW storage in which the various attributes of alternative store designs and management strategies are scored and collectively compared using the program OnBalance. By varying the weighting of the different attributes, the sensitivity of the overall score of the various designs to their attributes may be evaluated. Ultimately, the technical issues related to store design, construction and operation will have to be balanced against the non-technical factors that may influence the development of a store, particularly those related to stakeholder interactions and public concerns. Developing a long-term interim storage strategy requires a holistic approach that embraces all of these factors.