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UMAN: Understanding of uncertainty, risk and safety (EURAD WP)

UMANS is a Strategic Studies Work Package (WP) within EURAD. It aims to further refine methods of making sensitivity and uncertainty analyses, and develop a multi-actor network for uncertainty management.


Decisions associated with radioactive waste management programmes are made in the presence of irreducible and reducible uncertainties. Several choices made based on limited information in early programme phases may also have to be confirmed before or during the construction and operation of the facility. At the end of the process, uncertainties will inevitably remain, but it should be demonstrated that these uncertainties do not undermine safety arguments. Hence, the management of uncertainties is a key issue when developing and reviewing the safety case of waste management facilities and, in particular, of waste disposal facilities due to the long timescales during which the radiotoxicity of the waste remains significant.

As noted under the EURAD Roadmap Theme 1 – “Managing implementation and oversight of a radioactive waste management programme” – a clear strategy and commitment to the involvement of stakeholders is essential to the decision-making process at all stages of a waste management programme. It is also explained that scientific activities associated with a waste management programme (site characterisation, process modelling, safety assessment etc.) are evolving over time, leading to new viewpoints and sometimes new uncertainties and they are less predictable of the outcome, duration or resources that may eventually be required. Accounting for such uncertainty has thus become a key part of successful programme planning, and would benefit from continued sharing of methodologies and experience.

Therefore, uncertainty is a cross-cutting issue of the different themes and stages identified in the Roadmap. The term “uncertainty” is also explicitly mentioned in the title of several activities of common interest considered as having a medium or a high priority: Inventory uncertainty (1.1.1), Site uncertainty treatment (3.1), Geological uncertainties (1.6.2), Uncertainty treatment (2.1.3). Furthermore, RD&D activities are aimed at improving the state-of-knowledge and thus are expected to reduce uncertainties. Understanding the contribution of these activities to the overall uncertainty management is important for the different actors involved in the decision-making process, as well as for the identification of future EURAD priorities and activities.

Consequently, the raison d’être of this WP is to provide an opportunity to the organisations and different actors of the member states to share their experience and views on uncertainty management and to identify emerging needs associated with this topic. The WP will also contribute to understanding the added value of RD&D activities for the safety case and the decision-making process. It also contributes to the vision of EURAD by fostering mutual understanding and trust between Joint Programme (JP) participants.


This WP is dedicated to the management of uncertainties that are potentially relevant to the safety of different radioactive waste management stages and programmes. It includes various activities such as exchanges on views, practices and uncertainty management options and the review of existing strategies, approaches and tools. Interactions between different types of actors including civil society are central to this WP. These interactions are aimed at meeting the shared objective of fostering a mutual understanding of uncertainty management strategies, approaches and preferences. A particular focus is put on uncertainties which directly link with RD&D WPs and with a high (and where relevant medium) priority subdomain of the SRA, for which exchanges of information and experiences and strategic studies have been identified as beneficial by the JP actors themselves. The WP will consider past and present EU projects on the topics of interest and other initiatives carried out at an international level such as IAEA and NEA so as to avoid duplicating existing work. The WP will allow identification of the contribution of past and on-going RD&D projects to the overall management of uncertainties, as well as remaining and emerging issues associated with uncertainty management that could be addressed in subsequent waves of EURAD.