International developments in addressing environmental change in post closure safety assessments

Environmental change in post-closure safety assessment for radioactive waste disposal is recognised as an issue in international recommendations, national regulatory requirements and safety assessment practice. The reference biosphere's methodology, developed as part of the IAEA BIOMASS project (IAEA-BIOMASS-6), completed in 2001, considered processes relevant to environmental change, but did not take the issue very far technically. Further international work was done in the European project BIOCLIM and reported in 2004. Subsequently, a Working Group of the IAEA EMRAS II Program completed a study in 2012 of "Environmental Change in Post-Closure Safety Assessment of Solid Radioactive Waste Repositories". Following up the results of the above history of international studies, further work is in progress within the IAEA MODARIA program WG6, on "Development of a Common Framework for Addressing Climate Change in Post-Closure Radiological Assessment of Solid Waste Disposal". The key work in this project, introduced in this paper, includes: definition of the key processes that drive environmental change, describing how a relevant future may develop on a global scale; considering how that can be downscaled to provide information that is needed for site-specific assessments; and applying the conceptual framework to a number of case studies that illustrate the evolution of site characteristics and the implications for the dose assessment models.