Graded approach to nuclear safety - State of the practice

This report studies graded approach to nuclear safety from a literature perspective. The aim of the report is to obtain an overall picture of graded approach(es) and identify some of the main issues of the state-of-the-practice graded approach. The relationship of overall safety and graded approach, and future development needs for a risk-informed graded approach are studied.

Definitions and application areas of graded approach are collected from different sources to obtain an understanding of current uses of graded approach. One specific area of interest is graded approach regarding management systems. The role that management systems play for graded approach is in this report considered from what is found in literature. Literature on riskinformed decision making is presented for the background of risk-informed grading processes. The key aspects of a methodology for risk-informed grading are discussed, such as integration of qualitative and quantitative assessments.

Based on the literature review it is concluded that graded approach in nuclear safety is so far still a concept; a concept that could be developed in more detail in order to achieve an integrated framework applicable to most situations and users. Utilising an integrated collection of methods and tools in a risk-informed graded approach would require firstly integrating technical aspects with the other areas of overall safety, such as organisational factors.