Requirement of the assessment strategy for biosphere in mature safety cases for nuclear waste repositories – Finland case

Abstract

In safety assessments for nuclear waste disposal, the biosphere is a completely open system, whereas the bedrock can be treated with comparably simple boundary conditions. The bedrock has a vital role in providing and maintaining favourable conditions for the waste, but the public interest tends to focus on the biosphere. More importantly, the bedrock groundwater does arrive from the biosphere. Also, the regulations usually set the safety criteria in terms of doses occurring in the biosphere. Thus, it is reasonable to address the biosphere as a part of the disposal system, performance of which should be described based on conceptual models that cover phenomena and processes controlling radionuclide release and transport. From these, the actual assessment models and data are expected to be derived based on high-level research and expertise obtained through empirical study. In this paper, the complexity expected of a biosphere assessment within a mature safety case is discussed through the example of the Finnish regulations and recent safety cases for nuclear waste disposal. Both elaborate and complex presentations and stylised approaches have their benefits, and a balance needs to be sought.

The IGD-TP Geodisposal 2014: Introduction to the Conference Proceedings

“…Here papers are presented on: the safety case for the biosphere in the context of the mature, Finnish safety case (Ikonen, 2015); the influence of anthropogenic CO 2 on post-closure performance assessment (Lord et al, 2015); the design of waste packaging for heat generating wastes (Myers et al, 2015); development of a generic safety case narrative for the UK geological disposal facility (Bailey, 2015); and an integrated approach to disposal of the UK's carbon-14 wastes (Lever and Vines, 2015).…”