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The LLWR’s 2011 Environmental Safety Case

[+] Author Affiliations
Richard Cummings, Andrew J. Baker, Trevor Sumerling, John Shevelan, Amy Huntington

LLWR Ltd., Drigg, Holmrook, Cumbria, UK

Paper No. ICEM2011-59135, pp. 1331-1340; 10 pages
  • ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management
  • ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management, Parts A and B
  • Reims, France, September 25–29, 2011
  • Conference Sponsors: Nuclear Engineering Division and Environmental Engineering Division
  • ISBN: 978-0-7918-5498-3
  • Copyright © 2011 by ASME


The UK’s Low Level Waste Repository Ltd submitted an Environmental Safety Case (ESC) for the disposal of low-level waste to the Environment Agency on the 1st of May 2011. The ESC is a major submission that will decide the future use of the Repository and has major implications for the success of the UK’s LLW Strategy and decommissioning programme. This paper provides an overview of the work that has been carried out to support the submission. Key aspects of this ESC include: • detailed investigations of existing disposals, based on careful examination of existing records and other investigations, including interviews with former operational staff; • analysis of uncertainties in future disposals; • modelling of the biogeochemical evolution of the disposal system, which provides understanding of the evolution of pH, Eh and gas generation and thence underpinning for radionuclide releases in groundwater and gas; • development of a 3-D groundwater flow model, calibrated against observed heads and with a detailed representation of the engineered features; • analysis of coastal erosion and its impacts; • a major focus on optimisation based on detailed technical studies; • a conclusion that existing disposals do not require remediation; • the choice of a concrete vault design with permeable side walls designed to avoid bathtubbing after the end of management control; • a comprehensive set of assessment calculations, including thorough analysis of uncertainties, which demonstrate consistency with the Environment Agency’s risk and dose guidance levels; • revision of the LLWR’s WAC, based in part on the use of the ‘sum of fractions’ approach; • the use of a safety case document structure that emphasises key safety arguments in a Level 1 document and provides supporting evidence in a series of Level 2 documents; • the provision of a Level 2 document that describes in detail how each aspect of the regulatory guidance has been addressed. In the future, the 2011 ESC will be maintained using a formal system of change control. It will be used as a tool for decision making concerning the future development of the LLWR and waste acceptance.

Copyright © 2011 by ASME
Topics: Safety



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