Use of Risk Insights in the Practical Implementation of an Integrated Risk-Informed Decision-Making Framework

While general guidance for addressing individual elements of the key principles of risk-informed decision making (RIDM) for large commercial nuclear power plants is available in the literature, the implementation of RIDM can still be challenging, whether a mature RIDM framework exists or not. Traditionally, RIDM approaches have focused strongly on the use of risk information, particularly quantitative results from probabilistic risk assessments, with some individual guidance on other key principles such as defense in depth and safety margin. Addressing these different principles in an integrated, balanced fashion that utilizes the strengths of each principle while understanding the impact of uncertainties is not as easily implemented. In fact, the evaluation of each principle in isolation can lead to inadequate input for decision-making purposes, while heavily relying on any single principle can negate the benefits from using a risk-informed approach. This technical note focuses on the specific challenges of the implementation of a truly integrated RIDM (IRIDM) framework and provides specific solutions and detailed discussions and examples. It discusses important clarifications of the key principles of RIDM and their intended implementation, as well as the interrelationships of the principles. A framework for IRIDM is presented that integrates the information that needs to be considered, documented, and communicated to decision makers.