NDA/RWM/167 Geological Disposal Science and Technology Plan 2020 October 2020 NDA/RWM/167 Geological Disposal Science and Technology Plan 2020 October 2020 NDA/RWM/167 Conditions of Publication This report is made available under the Radioactive Waste Management Limited (RWM) Transparency Policy. In line with this policy, RWM is seeking to make information on its activities readily available, and to enable interested parties to have access to and influence on its future programmes. The report may be freely used for non-commercial purposes. RWM is a wholly owned subsidiary of the Nuclear Decommissioning Authority (NDA), accordingly all commercial uses, including copying and re publication, require permission from the NDA. All copyright, database rights and other intellectual property rights reside with the NDA. Applications for permission to use the report commercially should be made to the NDA Information Manager. Although great care has been taken to ensure the accuracy and completeness of the information contained in this publication, the NDA cannot assume any responsibility for consequences that may arise from its use by other parties. © Nuclear Decommissioning Authority 2020. All rights reserved. ISBN 978-1-84029-600-6 Other Publications If you would like to see other reports available from RWM, a complete listing can be viewed at our website https://rwm.nda.gov.uk, or please write to us at the address below. Feedback Readers are invited to provide feedback on this report and on the means of improving the range of reports published. Feedback should be addressed to: RWM Feedback Radioactive Waste Management Limited Building 329 Thomson Avenue Harwell Campus Didcot OX11 0GD UK email: [email protected] ii NDA/RWM/167 Abstract This Science and Technology Plan presents an analysis of the nature and timing of RWM’s future technical development activities. The document is primarily an internal document, however publication of this document will provide opportunities for dialogue and involvement of interested parties in the development of our knowledge base for the safe geological disposal of radioactive waste. Feedback is welcomed, particularly in relation to innovative approaches which may address the identified research needs and objectives. This is a third issue of the Science and Technology Plan, containing a number of enhancements from the previous issue. iii NDA/RWM/167 Executive Summary Radioactive Waste Management Limited (RWM) is the UK Government’s nominated implementer for delivering a geological disposal facility for the UK’s higher activity radioactive wastes. The purpose of this document, the ‘Science and Technology Plan’, is to provide details of the nature and timing of our planned technical development activities. It is intended that publication of this document will provide opportunities for dialogue and involvement of interested parties in the development of our knowledge base for the safe geological disposal of radioactive waste. We welcome feedback, particularly in relation to innovative solutions to our identified research needs and objectives. In September 2014, we published our first Science and Technology (S&T) Plan. This was followed by a light update and re-publication in 2016. This document provides a more significant update incorporating improvements resulting from: learning and feedback from internal and external stakeholders; • feedback from our Regulators; • alignment with the Geological Disposal Technical Programme (which replaces the • S&T Programme document); an updated ‘change control’ appendix, identifying and justifying changes to the • previously published plan, and providing an audit trail for completed tasks; new tasks, recognising the iterative development of the GDF project and out-year • planning; and a new numbering system for task identification with improved longevity and • traceability. This document comprises a short discussion of the context within which this plan has been developed and the methodology which we have used to develop the detailed analysis, together with the detailed plan contained in the appendices to this document: Appendix A is a breakdown of all the topics within RWM’s technical programme • which require research and development in this generic phase of our programme. Appendix B comprises a set of task sheets describing the specific research • requirements in a structured manner which provides stakeholders with clarity of the specific research drivers, objectives and suggested scope of every task we currently foresee to be required to appropriately address RWM’s generic knowledge gaps. Appendix C documents changes to the plan between version 2 and version 3. • Appendix D is a simple long-range graphic showing the phasing of the generic • research and development activities detailed in Appendix B, the individual tasks identified in this graphic are hyperlinked to the relevant task sheets. RWM is currently engaged with the process of identifying potentially suitable sites for a GDF and willing communities. The time horizon for this S&T Plan is a decade. During this time we will continue to transition from a generic programme to a programme of technical work necessary to develop a GDF at a site-specific level. Throughout our analysis of knowledge gaps and their proposed closure we have utilised Scientific Readiness Levels (SRLs™), developed by the National Nuclear Laboratory along with Technology Readiness Levels (TRLs) which are widely used across the NDA estate, as tools to consider the maturity of the knowledge base as it evolves, and to consider the level of maturity required to support each stage of the Technical Programme. We have prioritised the schedule in line with the projected budget underpinning RWM’s technical programme, utilising a series of prioritisation questions and recognised drivers for research and development. v NDA/RWM/167 Having undertaken three decades of research into the geological disposal of UK wastes, significant progress has been made. Challenges to the viability of geological disposal concepts have been overcome (although implementation may be subject to site-specific challenges) and the remaining key uncertainties are currently subject to large focused research projects. Once potential candidate sites have been identified, a programme of site investigation will be undertaken in order to reflect the real environment in the safety case, together with research, development and demonstration studies associated with the optimisation of the disposal system to the local geological environment. Such tasks are identified in the Science and Technology Plan, together with the body of technical development work required to address knowledge gaps associated with the Disposal System Safety Case, disposal concept development and disposal system design. vi NDA/RWM/167 List of Contents Conditions of Publication ii Abstract iii Executive Summary v List of Abbreviations ix Glossary xiii 1 Introduction 1 2 Purpose of this Document 5 3 Development of Our Knowledge Base 7 4 Assessment and Comparison of Scientific Maturity 11 5 Description of Science and Technology Plan Contents 15 6 Transitioning from Generic with Site Specific Research 19 7 Review and Scrutiny 21 8 Feedback 23 References 25 Appendix A Product Breakdown Structure 27 Appendix B Task Sheets 29 B1 WBS 10 - Biosphere 29 B2 WBS 20 - Criticality Safety 63 B3 WBS 30 - Engineered Barrier Systems (EBS) and their Evo- lution 148 B4 WBS 40 - Gas Pathway 219 B5 WBS 50 - Geosphere 273 B6 WBS 70 - Modelling and Treatment of Uncertainty 335 B7 WBS 80 - Groundwater Pathway for Radionuclide & Non- radionuclide Species 339 vii NDA/RWM/167 B8 WBS 90 - Waste Container Evolution 418 B9 WBS 100 - Waste Package Accident Performance 446 B10 WBS 110 - Wasteform Evolution 510 B11 WBS 210 - Social Science 567 B12 WBS 220 - Environmental Safety Case (ESC) 569 B13 WBS 310 - Concept Options and Alternatives 580 B14 WBS 320 - Waste Inventory Characterisation 586 B15 WBS 410 - Sub-surface Facilities Design and Operational Safety 589 B16 WBS 420 - Surface Facilities Design and Operational Safety 606 B17 WBS 430 - Transport System and Containers Design and Safety 613 B18 WBS 510 - Site Characterisation 627 B19 WBS 610 - Strategic Waste Programmes 633 Appendix C Change Log: Breakdown by Work Area 637 Appendix D Wiring Diagrams 725 viii NDA/RWM/167 List of Abbreviations ACSIS Atmospheric Corrosion of Stainless Steel in Interim Stores AGR Advance Gas-Cooled Reactor ALARP As Low As Reasonably Practicable ANDRA Agence Nationale pour la gestion des Déchets Radioactifs (French national radioactive waste management agency) ARFAC Activity Release in Fire Accident Conditions BEPO British Experimental Pile BFS Blast Furnace Slag BIOMASS BIOsphere Modelling and ASSessment BWR Boiling Water Reactor CAAS Criticality Accident Alarm System CAE Claims, Arguments, Evidence CAST Carbon-14 Source Term CDP Cellulose Degradation Products CIDS Criticality Incident Detection System CR Concentration Ratio CSA Criticality Safety Assessment CSSP Construction Site Security Plan DBE Deutsche Gesellschaft zum Bau und Betrieb von Endlagern für Abfallstoffe (German company for the construction and operation of repositories for waste) DCIC Ductile Cast Iron Container DCO Development Consent Order DCTC Disposal Container Transport Container DECOVALEX Development of Coupled Models and their Validation Against Experiments DNLEU Depleted, Natural and Low-Enriched Uranium DRZ Disturbed Rock Zone DSSC Disposal System Safety Case EA Environment Agency