Proposal for a technology-neutral safety approach for new reactor designs

Many states are considering an expansion of their nuclear power generation programmes. Many of the technologies and concepts are new and innovative. The current design and licensing rules are applicable to mostly large water reactors and there are no accepted rules in place for design, safety assessment and licensing for new innovative nuclear power plants. This TECDOC proposes a (new) safety approach and a methodology to generate technology-neutral (i.e. independent of reactor technology) safety requirements and a 'safe design' for advanced and innovative reactors. The experience gained in decades of design and licensing, combined with the development of risk-based concepts, has provided insights that will form the basis for new safety rules and requirements. Many lessons learned acknowledge the importance of such concepts as safety goals and defence in depth and the benefits of integrating risk insights early in an iterative design process. A new safety approach will incorporate many of the new developments in these concepts. For example, the probabilistic elements of defence in depth will help define the cumulative provisions to compensate for uncertainty and incompleteness of our knowledge of accident initiation and progression. This TECDOC also identifies areas of work, which will require further definition, research and development and guidance on application. This publication is to be used as a guide to developing a new technology-neutral safety approach, and as a guide in the application of methodologies to define the safety requirements for an innovative reactor designs. The method proposes an integration of deterministic and probabilistic considerations with established principles and concepts such as safety goals and defence in depth. The TECDOC recommends that the structure of the new technology-neutral main pillars for the design and licensing of innovative nuclear reactors be developed following a top-down approach to reflect a newer risk-informed and less prescriptive technology-neutral framework. The TECDOC describes an overall strategy to define safety requirements (and a safe design), which are both technology-neutral and technology-specific. However, this TECDOC focuses primarily on the development of technology-neutral safety requirements. This TECDOC does not establish specific quantitative safety goals. Ultimately, this work may lead to a set of safety requirements, subjected to a consensus process similar to that existing for current NPPs. It is also expected that this TECDOC will provide useful input to the current process for the review of the IAEA Safety Standards Series No. NS-R-1 (The Safety of Nuclear Power Plants: Design). This publication has been prepared by a group of experts from a select number of interested Member States and at this stage does not reflect the results of a large consensus process