A “safety case” is the synthesis of evidence, analyses and arguments that quantify and substantiate a claim that a geological repository for radioactive waste will be safe after closure and beyond the time when active control of the facility can be ensured. The NEA project on International Experiences in Safety Cases for Geological Repositories (INTESC) analysed existing safety cases, and their elements, to provide an overview of progress during the last decade, to identify key concepts and to give insight into regulatory expectations on the contents and review of safety cases. This report documents the outcomes of the INTESC project. It takes account of the responses to a detailed survey of NEA member countries as well as the results of a technical workshop.
The project has shown that the purpose and concept of a safety case are generally understood, accepted and adopted by radioactive waste management programmes worldwide. Programmes are preparing safety cases in line with most of the elements suggested by the NEA, although there are some differences in interpretation and presentation. Some important trends are emerging, such as the use of safety functions and the role of a geosynthesis. Further development of some aspects and tools, such as quality assurance programmes and requirements management systems, can be expected as safety cases are further refined to support programmes moving towards implementation of geological disposal.