Experience of Safety Assessment for the Deep Disposal of Intermediate-Level Waste in the U.K.

Abstract

United Kingdom Nirex Ltd is investigating Sellafield as a potential site for the deep geological disposal of solid intermediate-level waste (ILW) and some low-level radioactive wastes (LLW). Attention is currently focused on a potential repository located in volcanic rocks (the Borrowdale Volcanic Group, BVG) at a depth of 650 m below ordinance datumOD. This paper summarises Nirex 95 [1], a preliminary analysis of the groundwater pathway for this repository. Nirex 95 has focused on the calculation of annual individual risk, which is a principal safety requirement as set out by the U.K. regulatory bodies [2]. It is not a comprehensive safety assessment, which would require the systematic analysis of a wider range of features, events and processes. However, it does illustrate a number of key components of the methodology employed in the Nirex programme.