Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 5 1 2009 10.5194/cpd-5-463-2009 http://www.clim-past-discuss.net/5/463/2009/ http://www.clim-past-discuss.net/5/463/2009/cpd-5-463-2009.html http://www.clim-past-discuss.net/5/463/2009/cpd-5-463-2009.pdf 463 494 2009-02-13 How to treat climate evolution in the assessment of the long-term safety of disposal facilities for radioactive waste: examples from Belgium M. Van Geet m.vangeet@nirond.be M. De Craen D. Mallants I. Wemaere L. Wouters W. Cool Belgian Agency for Radioactive Waste and Enriched Fissile Materials, ONDRAF/NIRAS, Kunstlaan 14, 1210 Brussels, Belgium Belgian Research Institute for Nuclear Energy, SCKCEN, Boeretang 200, 2400 Mol, Belgium In order to protect man and the environment, long-lasting, passive solutions are needed for the different categories of radioactive waste. In Belgium, three main categories of conditioned radioactive waste (termed A, B and C) are defined by radiological and thermal power criteria. It is expected that Category A waste – low and intermediate level short-lived waste – will be disposed in a near-surface facility, whereas Category B and C wastes – high-level and other long-lived radioactive waste – will be disposed in a deep geological repository. In both cases, the long-term safety of a given disposal facility is evaluated. Different scenarios and assessment cases are developed illustrating the range of possibilities for the evolution and performance of a disposal system without trying to predict its precise behaviour. Within these scenarios, the evolution of the climate will play a major role as the time scales of the evaluation and long term climate evolution overlap. In case of a near-surface facility (Category A waste), ONDRAF/NIRAS is considering the conclusions of the IPCC, demonstrating that a global warming is nearly unavoidable. The consequences of such a global warming and the longer term evolutions on the evolution of the near-surface facility are considered. In case of a geological repository, in which much longer time frames are considered, even larger uncertainties exist in the various climate models. Therefore, the robustness of the geological disposal system towards the possible results of a spectrum of potential climate changes and their time of occurrence will be evaluated. The results of climate modelling and knowledge of past climate changes will merely be used as guidance of the extremes of climate changes to be considered and their consequences. AECL: Environmental Impact Statement on the Concept for Disposal of Canada's Nuclear Fuel Waste. Atomic Energy of Canada Limited Report, AECL-10711, COG-93-1, Pinawa, Canada, 1994. 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NAGRA: Project Opalinus Clay, Safety Report, Demonstration of disposal feasibility for spent fuel, vitrified high-level waste and long-lived intermediate-level waste (Entsorgungsnachweis), NAGRA technical Report 02-05, 2002. ONDRAF/NIRAS: Selection and description of scenarios for long-term radiological safety assessment, Project near surface disposal of category A waste at Dessel, NIROND-TR 2007-09E, 2008a. ONDRAF/NIRAS: Safety assessment methodology for category B&C waste. NIROND-TR-, in preparation, 2008b. British Nuclear Fuels: Drigg post-closure safety case: Overview report, BNFL, United Kingdom, 2002. Van Humbeeck, H. and Bastiaens, W.: Demonstrating the construction and backfilling feasibility of the Supercontainer design for HLW, Proceedings of Radioactive Waste Disposal in Geological Formations International Conference (REPOSAFE), Braunschweig, 6–9 November 2007, 336–345, 2007. Wemaere, I., Hardy, L., Van Keer, I., Marivoet, J., Labat, S. and Sillen, X.: A palaeohydrogeological study of the Mol site, Belgium (phymol project), ec Doc. rtd/0056/2000-en, prepared by sckcen, EC, Brussels, 2000, NEA, Consideration of timescales in post-closure safety of geological disposal of radioactive waste, NEA report NEA/RWM/IGSC(2006)3, 2007.