INTEGRATED RISK INFORMED DECISION                                                                 2
       MAKING
          Learning objectives
          After completing this chapter, the trainee will be able to:
          1. Define the fundamental safety objectives.
          2. Define design extension conditions.
          3. Define integrated risk-informed decision making process.
                                          Basic Professional Training Course; Module VIII
                                            Integrated risk informed decision making
       INTEGRATED RISK INFORMED DECISION                                                                 3
       MAKING – Introduction
       •   IAEA SF-1:
           − Fundamental Safety Objective is to protect people and the environment 
                from the harmful effects of ionizing radiation.
           − To achieve this objective, a comprehensive safety analysis needed.
           − Initially DSA used as guidance for design and operation:
                 − Defence-in-depth;
                 − Safety margins;
                 − Single failure criterion;
                 − Etc.
                                          Basic Professional Training Course; Module VIII
                                            Integrated risk informed decision making
                                                                                                         4
       Introduction – cont.
       •   DSA presumed that residual risk of unacceptable radiological 
           releases is sufficiently low.
       •   It did not however define “how low is low enough”.
       •   The accidents have shown that qualitatively assured “low risk” was 
           not always the case.
       •   PSA technology started in 1975 with WASH 1400.
       •   Qualitative assessment of risk and gives answers to:
           − What can go wrong?
           − How likely is it?
           − What are the consequences?
                                          Basic Professional Training Course; Module VIII
                                            Integrated risk informed decision making
                                                                                                         5
       Introduction – cont.
       •   The main advantages of PSA:
           − CDF;
           − Frequency of radioactive release;
           − Frequency of harmful health effects for the population;
           − Other consequences.
       •    “Measure” of compliance with quantitative safety goals.
                                          Basic Professional Training Course; Module VIII
                                            Integrated risk informed decision making
                                                                                                         6
       Introduction – cont.
       •   Both DSA and PSA must be used.
       •   GSR Part 4 states:
           − “The results of the safety assessment have to be used to make 
                decisions in an integrated, risk informed approach, by means of 
                which the results and insights from the deterministic and 
                probabilistic assessments and any other requirements are 
                combined in making decisions on safety matters in relation to the 
                facility or activity.”
                                          Basic Professional Training Course; Module VIII
                                            Integrated risk informed decision making