Other technical concepts than mining could accelerate site exploration and construction of final disposal. New hypothetical concepts and technologies can be presented here. Administrative and procedural processes for site selection are excluded.

Quantitative safety assessments for geologic disposal comprise an assessment of the overall level of performance of a repository and an analysis of the associated uncertainties. Such assessments rely on system-level models that are applied to predict the behavior of the whole system under consideration, which in turn are supported by process-driven submodels that assess individual components of the repository system. Many factors defining the evolution of a repository involve complex processes that are quite challenging to predict over short and long time scales, thus demonstrating model fidelity and accounting for prediction uncertainties is an unavoidable aspect of a safety case. Furthermore, results from uncertainty analyses need to be formulated in a clear way understandable to the public and other stakeholders.
This session seeks contributions on how model uncertainties of different nature - scenario uncertainty, conceptual and numerical model uncertainty, and parameter uncertainty – can be evaluated and potentially reduced, how they can be best incorporated in both system and submodels to avoid error propagation, and how uncertainty evaluations can be best communicated to achieve and maintain acceptance. Possible topics include:
• Model comparison against experimental data from lab- and field-based studies as well as natural analogs
• Benchmarking and model comparison studies
• Uncertainty quantification via probabilistic and deterministic approaches
• Transferring information from submodels to system-level models: Upscaling, simplifications, and abstractions
• Propagation of uncertainty between submodels and system-level models
• Assessing uncertainty over very long time frames
• Communicating model uncertainties to the public and other stakeholders
• Case studies from national and international programs and initiatives

Site selection procedures for deep geological repositories (DGRs) that aim to find the site with the best possible safety, out of a set of possible sites, will face one challenge: To compare the safety of two sites. While at the beginning of the selection process, it may be possible to reduce the number of sites by means of indicators that map geoscientific parameters against some agreed indicator standard, sooner or later, when the number of potentially best possible sites becomes smaller, safety needs to be compared between two (or more) sites.

This session solicits oral presentations by (safety) scientists whose research contributes to the challenge of determining the safer site of two.

The session goals:

To provide a platform for scientific exchange in this field, which has not experienced abundant scientific exchange so far.

To raise awareness in the wider community for the challenge under focus in this session.

To discuss the opportunities for increasing the efficiency of site selection procedures by addressing the issue early.

Based on the advanced insights gained from previous work, the further process can be accelerated by a paradigm shift in the approach, enabling a significantly earlier start of storage.
Central Thesis:
The paradigm shift is based on two key pillars:
1. From Searching to Finding:
Instead of a lengthy search process, the focus is on the vision of active finding. This approach emphasizes clearly defined, actionable criteria and the targeted identification of sites that already meet these requirements, rather than pursuing indefinite or diffuse search procedures. The reorientation requires a clear vision and determination, viewing potential sites as solution partners rather than mere locations.
2. From Bureaucratic Enforcement to a Strategy of Willing Applicants:
Rather than slowing down the process through bureaucratic structures and a complex approval process without clear accountability, a voluntary and collaborative approach is chosen. This paradigm shift relies on a strategy where interested regions or communities can actively apply to host the storage. To encourage this willingness, a generous compensation package will be offered, including financial incentives, infrastructure development projects, and long-term economic benefits. This process aims not only to increase acceptance but also to ensure responsible and transparent collaboration between the state, the economy, and society.
Session Goal:
The session will discuss and evaluate the potential of this new strategy. The focus is on how storage from 2040 can be realized faster, more efficiently, and with greater societal acceptance, without compromising safety and long-term responsibility.
Discussion Questions:
• How can the shift from a search to a finding process be implemented?
• What incentives are necessary to motivate regions to voluntarily apply?
• How can a fair compensation system be ensured?
• What role does communication and public involvement play in this process?

The participatory turn in radioactive waste management has manifested itself in many countries through a discursive and practical involvement of citizens in the long-term management of various waste categories. In most cases, such involvement has primarily focused on repository planning and siting. However, the lifetimes of repositories and radioactive waste extend far beyond these early implementation stages, which themselves often span various decades – or even longer. To seriously address civil society involvement in radioactive waste management, this means we also need to consider the ways in which civil society groups and individual citizens could be engaged in this management over longer periods of time. Some initial scholarly commitment with this topic is currently developing, with theoretical and empirical work being conducted around concepts such as stewardship, care and hosting. However, a range of questions remain to be further explored, such as; What does it mean to pass engagement on from one generation to the next, and how could/should such intergenerational involvement be facilitated?; What sort of consequences could long-term engagement with civil society have regarding institutional responsibilities ?; How can participatory structures be adapted in such ways that they remain both sufficiently durable and flexible?; What meaningful role(s) are envisaged or intended to be played by civil society actors at later stages of a repository lifetime, especially also post-closure?; How could the different roles of actors over time be considered meaningful?; How can repository projects enact future opportunities for civic engagement?; What kinds of socio-technical governance structures or systems might emerge from these long-term interactions?

This session will delve into these questions and more, inviting contributions from diverse scientific disciplines. We particularly welcome insights related to intergenerational participation, stewardship, sociology of care, awareness preservation, youth involvement, innovative forms of civic participation and similar topics. By addressing these issues, we aim to build a deeper understanding of how long-term civil society involvement in radioactive waste management can be sustained and enriched over time.

Public opinion is often considered to be a key aspect for ensuring the long-term success of dealing with nuclear waste. Thus, it is of high relevance to collect robust empirical knowledge on how ordinary citizens perceive the current challenges of high-level radioactive waste, decommissioning of nuclear infrastructure as well as interim and long-term storage. In addition, regulators and operators must know what citizens expect from them and which role citizens want to play themselves in decision-making processes around nuclear waste management. Given the fragmentation of society, it is also important to answer these questions not only for the population as a whole but also separately for different strata. This also sets the foundation to provide explanations for current public opinion rather than just describing it.

This session aims to bring together public opinion research on nuclear waste management from all around the globe to learn from different perspectives and approaches. Submissions may address but are not limited to the following key areas and research questions:
• Knowledge and beliefs: What is the current level of knowledge in the population or specific groups on how nuclear waste is handled? Do citizens are aware who is responsible for dealing with the waste and were it is stored? What are beliefs in society on the risks around nuclear waste?
• Attitudes: Which strategies for dealing with radioactive waste do citizens support or oppose? How does the population judge the current work of regulators and operators? Which are the key dimensions citizens use to judge success and failure in dealing with nuclear waste?
• Needs: Which information needs around nuclear waste do citizens articulate? How much and in which ways does the population want to be actively involved in decision-making processes concerned with nuclear waste management?
• Antecedents: Which variables explain inter-individual differences in citizens’ attitudes, emotions, knowledge beliefs and/or needs around nuclear waste management? How can changes in these variables contribute to normatively desirable levels of knowledge in the population?
• Consequences: What consequences do have certain attitudes, knowledge and needs for potential actions of citizens towards nuclear waste? How do these individual level actions affect other individuals and/or society as a whole?
• Institutional reactions: Which conclusions can be drawn from public opinion data on how regulators and operators of nuclear waste management should adapt their policies? Which implications derive for their communicative and participatory practices?
• Conceptual: How does the relatively low issue salience of the topic in society affect the measurement of public opinion on nuclear waste on the individual level? Which degree of volatility in public opinion should be assumed? Which implications do both may have for conclusions drawn from public opinion data?
• Methodological challenges: How can be ensured that survey data remains representative for the population in times of decreasing response rates? Which actions can be taken to increase the validity of measurements of public opinion in society? How can computational methods contribute to better understand public opinion derived from digital trace data? Which new pathways exists to increase the comparability of studies across contexts, regions, and countries?
• Desiderata: What are the most important blind spots in recent public opinion research on nuclear waste? Which topics are overlooked that may are relevant to better understand public opinion on the topic, its antecedents or consequences?

Contributions are welcome that employ quantitative methods of the social sciences such as:
• Surveys
• Lab, survey, or field experiments
• Quantitative text analyses
• Network analyses
• Observational studies

As siting processes for large-scale infrastructures move further along the timeline, the relevance of potential siting regions increases as it becomes clearer where they could be located. As potential locations for large-scale infrastructures, regions consequently take on a central role in the process. This session thus explores the nexus of regions and the siting of large-scale infrastructures such as final repositories for nuclear waste, power plants, dams, and other examples.

We invite contributions from the social sciences, humanities and related fields on this topic. Contributions that do not only address the siting of nuclear waste but that take a broader view and/or address comparable siting processes are explicitly welcomed. They can tackle the following four broad themes but are not limited to them:

• Regional Development: Large-scale infrastructures often bring economic benefits to regions, but at the same time also impose burdens like pollution, noise, and environmental changes. National governments and private corporations alike often attempt to address such issues through compensations with the goal of regional development. How can sustainable and successful regional development be achieved? What is the long-term impact of such interventions? How can ‘development’ be conceptualized and how could this differ between regions?

• Regional Discourses and Attitudes: Siting processes may prove controversial on the regional level. Diverging local interests can culminate around the topic. Understanding regional discourses and attitudes is thus essential for the overall siting process. This raises questions on how different regional actors perceive and evaluate issues, what might influence them but also how the regional, national, and even international level interact.

• Regional Participation: Siting decisions in democracies are nowadays almost always accompanied by formal and informal regional participation. The prospect of large-scale infrastructures close to one’s home presents a particularly pressing issue for many citizens and other local stakeholders. Here, participation can take on many forms, where major and minor design decisions sometimes greatly influence the results of deliberative and consultative procedures. This can for instance include the choice of instrument (mini-publics, “Planzellen”, conferences…), decision making power, eligibility, or agenda-setting. At the same time, involving marginalized groups remains a challenge.

• Relevance of Time: Large-scale siting processes such as the search for a final repository for nuclear waste often cover large timeframes. This comes with several challenges: How can participation be fostered and sustained over several decades? What is the role of changing regional identities, socio-economic factors, and perception of time scales?

Safeguards and non-proliferation are crucial to prevent the use of radioactive materials for military purposes. This session encompasses topics related to safeguards and non-proliferation issues in nuclear waste disposal. The scope of topics that could be placed in this session is intentionally broad. Possible topics are, e.g.,

1. Non-proliferation assessment of alternative disposal options such as reactor-based disposal and partitioning and transmutation;
2. Current, future, and long- term challenges and opportunities in safeguards implementation for disposal facilities (interim storage and geological disposal facilities);
3. Societal and political drivers in nuclear materials management with interconnections to safeguards and non-proliferation;
4. International safeguards, non-proliferation agreements and regulations in nuclear waste disposal, their technical requirements, and their impact on national regulations.
5. Material accountancy and disposal of waste containing fissile materials such as highly enriched uranium and plutonium.
6. Research and development of advanced and innovative methods and technologies for monitoring and verification such as satellite surveillance, on-site inspections, and nuclear material accountancy to ensure compliance with non-proliferation agreements in nuclear waste disposal.
7. Perspectives on the long-term evolution of the safeguards system and the non-proliferation regime, in particular with a view on nuclear disposal;
8. Safeguards and non-proliferation in crisis and incident situations;

The session is also intended to provide a platform for exchange between different scientific communities. It aims to foster interaction among groups that rarely have the opportunity to collaborate.