Abstract
AbstractHigher activity radioactive wastes remain hazardous for extremely long timescales, of up to hundreds of thousands of years. Disposing of such wastes deep underground presents the internationally accepted best solution for isolating them from the surface environment on associated timescales. Geological disposal programmes need to assess potential releases from such facilities on long timescales to inform siting and design decisions and to help build confidence that they will provide an adequate degree of safety. Assessments of geological disposal include consideration of the wastes, the engineered facility, the host geology and the surface and near-surface environment including the biosphere. This paper presents an overview of recent post-closure biosphere assessment studies undertaken in support of the Nuclear Decommissioning Authority Radioactive Waste Management Directorate disposal system safety case for geological disposal of the United Kingdom's higher activity radioactive wastes. Recent biosphere studies have included: (1) ensuring that the United Kingdom's approach to consideration of the biosphere in safety case studies continues to be fit for purpose, irrespective of which site or sites are considered in the United Kingdom's geological disposal programme; (2) updating projections of global climate and sea level, together with consideration of the potential importance of transitions between climate states; (3) considering geosphere–biosphere interface issues and their representation, including redox modelling and catchment-scale hydrological modelling; and (4) identifying key radionuclides and developing a series of reports describing their behaviour in the biosphere together with an evaluation of associated implications for post-closure assessment calculations.
Highlights
THE principle of disposing of radioactive waste in an engineered facility deep underground is to ensure multiple robust and durable barriers to contaminant releases, enabling radionuclides to decay before reaching the accessible environment
The Nuclear Decommissioning Authority Radioactive Waste Management Directorate (NDA RWMD) current approach to representing the biosphere is described in the Biosphere Status Report (Nuclear Decommissioning Authority, 2010a) that supports the disposal system safety case (DSSC) (Nuclear Decommissioning Authority, 2010b)
This paper provides an overview of recent post-closure biosphere assessment studies that have contributed to this overall objective
Summary
THE principle of disposing of radioactive waste in an engineered facility deep underground is to ensure multiple robust and durable barriers to contaminant releases, enabling radionuclides to decay before reaching the accessible environment. Key regulatory criteria for evaluating the performance of a geological disposal facility (GDF) are expressed in terms of potential doses and risks that might arise to the most exposed members of future populations. Such exposures will occur in the biosphere and will be largest in the vicinity of any releases to the biosphere. The Nuclear Decommissioning Authority Radioactive Waste Management Directorate (NDA RWMD) current approach to representing the biosphere is described in the Biosphere Status Report (Nuclear Decommissioning Authority, 2010a) that supports the disposal system safety case (DSSC) (Nuclear Decommissioning Authority, 2010b). This paper provides an overview of recent post-closure biosphere assessment studies that have contributed to this overall objective
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