The following is taken verbatim from the US Nuclear Regulatory Commission White Paper on risk-informed and performance-based regula­tion (USNRC, 1975):

A ‘risk-informed’ approach to regulatory decision-making represents a phi­losophy whereby risk insights are considered together with other factors to establish requirements that better focus licensee and regulatory attention on design and operational issues commensurate with their importance to health and safety. A ‘risk-informed’ approach enhances the traditional approach by: (a) allowing explicit consideration of a broader set of potential challenges to safety, (b) providing a logical means for prioritizing these challenges based on risk significance, operating experience, and/or engineering judgment, (c) facili­tating consideration of a broader set of resources to defend against these challenges, (d) explicitly identifying and quantifying sources of uncertainty in the analysis, and (e) leading to better decision-making by providing a means to test the sensitivity of the results to key assumptions. Where appropriate, a risk-informed regulatory approach can also be used to reduce unnecessary conservatism in deterministic approaches, or can be used to identify areas with insufficient conservatism and provide the bases for additional requirements or regulatory actions.

Risk-informed decision-making is an on-going activity that continues throughout the life of the plant. It is based on the safety assessment of the power plant as it exists at a given point in time, including all changes, updates, and ageing effects that are important to safety (GSR Part 4, 2009). The following is taken verbatim from the GSR document, as a statement of the necessary background for risk-based decision making:

The responsibility for carrying out the safety assessment rests with the respon­sible legal person; that is, the person or organization responsible for the facility or activity — generally, the person or organization authorized (licensed or reg­istered) to operate the facility or to conduct the activity. The operating organi­zation is responsible for the way in which the safety assessment is carried out and for the quality of the results. If the operating organization changes, the responsibility for the safety assessment has to be transferred to the new operat­ing organization. The safety assessment has to be carried out by a team of suitably qualified and experienced people who are knowledgeable about all aspects of safety assessment and analysis that are applicable to the particular facility or activity concerned.

Clearly, the operating organization is expected to establish the infrastruc­ture for carrying out the safety assessment to the satisfaction of the national regulatory agency. In addition, it is essential to find a proper framework for carrying out a satisfactory decision-making process to enable risk-informed decisions.