Key Topic 1: Post-closure Safety Case


The purpose of the safety case is to gather all the scientific and technical arguments and evidence required to robustly support the safety claims of disposal facilities and systems. Safety is demonstrated by providing clear reasoning based on sound scientific and technological principles [i].  The safety case should be both robust and easily understandable.  Moreover, the safety case sets out the arguments and evidence seeking approval of the licensing documentation for specific nuclear waste disposal facilities and must therefore comply with the various requirements set out by the relevant national authorities. Attention should also be devoted to recommendations suggested by international organisations such as the IAEA and the OECD/NEA.

The safety case must describe the evolution of the repository in such a way that it provides a reasonable representation of the events that might occur, and that also provides a clear indication of the uncertainties included in the description.  This topic covers safety case and safety assessment issues related to the evaluation of the radiological impact of the whole repository on humans and the environment, and includes the evolution of the site over geological timescales (e.g. assessing the impact of processes such as erosion and climate change).  The impact of the repository and its components are covered under Key Topic 3.

[i]       OECD/NEA (2004). Post-closure safety case for geological repositories, Nature and purpose, NEA No. 3679, 2004.


The objectives of the research area, all of which are related to the “Safely Operate” pillar of the IGD-TP’s Vision 2040, are to:

  • Develop a broad view on the basis of the results of long-term safety assessments and enhance confidence in the concepts and the scenarios presented, thereby supporting development of the scope and content of subsequent safety cases for all IGD-TP participants.
  • Develop and refine the concepts and models applied to improve long-term safety assessments.
  • Improve the way in which sensitivities and uncertainties are addressed and communicated.
  • Further improve dialogue and engagement with the relevant authorities and other stakeholders.