Over the past two decades, the safety case has become a powerful and essential tool to support decision making for every stage of a geological disposal programme. Now, an increasing number of national programmes are advancing towards licencing and the realisation of their deep geological repository (DGR) for high-level radioactive waste. Licensing is a milestone achievement in the evolution and periodic updating of the safety case following an iterative process of research, site characterisation, design development and demonstration, safety assessment and integration, generally spanning over multiple decades. This is accompanied by regulatory reviews and ongoing communication with involved stakeholders. Throughout this process the entire lifecycle of the waste, from its generation to its ultimate disposal, is duly considered. Of particular importance is the embedding of optimisation within the process, so as to achieve the best outcomes for safety, technical feasibility, sustainability, costs and to fulfil stakeholder expectations and requirements. 

This stepwise process follows the holistic approach to waste management and entails, amongst others, the transfer of information between the different stages of waste generation and management, in the form of data, criteria, liabilities, decisions and requirements. The safety case provides the framework for integrating all information relevant to the DGR to support the decisions taken at each stage of this process. The NEA Integration Group for the Safety Case (IGSC) has developed the structure and essential elements of the safety case, such that a conceptual safety case, first developed at the early stages of a programme, can be progressively developed and deployed at later stages of the programme. Safety case digitalisation as well as knowledge preservation and transfer through expert generations are now being recognised as key for the successful iteration and development of the safety case towards DGR implementation.

The maturity of the safety case concept as developed by IGSC and national and international programmes has reached a high level, providing the basis to explore new domains, such as gathering and using experience obtained from already-operating repositories for other types of radioactive waste, including insights on operational issues and waste acceptance, as well as transfering the safety case methodologies to other disposal concepts.

The symposium was the fourth in a series IGSC had been organising since 2007, in co-operation with other international organisations. It provided a forum in which these topics could be addressed, with presentations from programmes at different stages and extensive discussions about the issues raised. Symposium participants were informed about the status of new activities of the IGSC 2023-2025 Programme of Work that were under way.

The objectives of the fourth IGSC symposium were to:

• Identify the key success factors from safety cases that have supported successful licensing steps, examining the lessons learned and the challenges faced in this regard by advanced DGR programmes;
• Understand how a safety case evolves through the different initial stages of a disposal programme, from the generic through to the site-specific stage, and then through the construction stages;  
• Explore the role of specific features, such as requirement management systems and information, data and knowledge management (IDKM) in building a safety case and in supporting its evolution throughout successive key milestones in a disposal programme;
• Practically apply knowledge sharing by involving early career scientists in the symposium, enabling them to exchange knowledge and discuss their views, ideas and expectations, with the aim of building an enduring network to support the next generation;
• Continue building on the 2022 NEA workshop on development of safety cases for different types of disposal facilities, exchanging experience with other non-DGR disposal facilities was addressed, especially regarding the application of holistic approaches to waste management:
  • the involvement of different type of stakeholders, particularly the communication of the safety case with them;
  • key challenges faced at different stages, including interaction with regulatory bodies, operational safety, waste acceptance, the management of uncertainty and the development and maintenance of a safety culture.

For more information about the Symposium programme, please download the flyer. 

• Keynote lectures (invited talks) on:
  • Radioactive waste management and the safety case in Hungary;
  • Requirement management systems;
  • Learning from nuclear facilities and mining industry;
  • Information, data and knowledge management.
• Plenary sessions and invited talks on:
  • Role and evolution of the safety case when moving to implementation;
  • Information, data and knowledge management (IDKM);
  • Derivation and management of criteria and requirements;
  • Learning from nuclear facilities.
• Avant-Garde sessions:
  • Disposal of unconventional and legacy waste;
  • Waste from next generation reactors;
• Oral and poster presentations on:
  • Derivation and implementation of criteria and requirements;
  • Disposal of unconventional and legacy waste;
  • Waste from next generation reactors;
  • Regulator, implementer and stakeholder dialogue;
  • Safety assessment and research, development and demonstration;
  • Safety case: Moving forward in the face of uncertainty;
  • Information, data and knowledge management (IDKM);
  • Learning from operating disposal facilities (optimisation, operation…)
• Young professionals’ network
• Expert panels
• Interactions and scientific co-operation with EC/EURAD programmes

Manuel CAPOUET (ONDRAF/NIRAS)
Ulrich NOSECK (GRS)
Alexander CARTER (NWS)
Peter MOLNAR (PURAM)
Thomas KAEMPFER (OST/NAGRA)
Ann-Kathrin LEUZ (ENSI)
Lucy BAILEY (NWS)
Doug ILETT (Env. Agency)
Jens MIBUS (BASE)
Frederic BERNIER (FANC)
Tom PEAKE (EPA)
Julie BROWN (CNSC)
Sylvie VOINIS (Andra)
Seif BEN HADJ HASSINE (EC/EURAD)
John STEIN (OECD NEA)
Soufiane MEKKI (OECD NEA)
Zhuoran LI (OECD NEA)
Rebecca TADESSE (OECD NEA)

At the end of the Symposium, an optional site visit was organised to Bátaapáti Repository for the disposal of low level waste at 250m below ground. The visit was organised by the host PURAM. 

For more information on the repository: https://rhk.hu/timeline/national-radioactive-waste-repository

Photo by Kate Kasiutich on Unsplash