Deterministic Safety Analysis For Nuclear Power Plants

The objective of this Safety Guide is to provide harmonized guidance to designers, operators, regulators and providers of technical support on deterministic safety analysis for nuclear power plants. It provides information on the utilization of the results of such analysis for safety and reliability improvements. The Safety Guide addresses conservative, best estimate and uncertainty evaluation approaches to deterministic safety analysis and is applicable to current and future designs. Contents: 1. Introduction; 2. Grouping of initiating events and associated transients relating to plant states; 3. Deterministic safety analysis and acceptance criteria; 4. Conservative deterministic safety analysis; 5. Best estimate plus uncertainty analysis; 6. Verification and validation of computer codes; 7. Relation of deterministic safety analysis to engineering aspects of safety and probabilistic safety analysis; 8. Application of deterministic safety analysis; 9. Source term evaluation for operational states and accident conditions; References.

The book has been developed in conjunction with NERS 462, a course offered every year to seniors and graduate students in the University of Michigan NERS program. The first half of the book covers the principles of risk analysis, the techniques used to develop and update a reliability data base, the reliability of multi-component systems, Markov methods used to analyze the unavailability of systems with repairs, fault trees and event trees used in probabilistic risk assessments (PRAs), and failure modes of systems. All of this material is general enough that it could be used in non-nuclear applications, although there is an emphasis placed on the analysis of nuclear systems. The second half of the book covers the safety analysis of nuclear energy systems, an analysis of major accidents and incidents that occurred in commercial nuclear plants, applications of PRA techniques to the safety analysis of nuclear power plants (focusing on a major PRA study for five nuclear power plants), practical PRA examples, and emerging techniques in the structure of dynamic event trees and fault trees that can provide a more realistic representation of complex sequences of events. The book concludes with a discussion on passive safety features of advanced nuclear energy systems under development and approaches taken for risk-informed regulations for nuclear plants.

Deterministic safety analysis is an essential component of safety assessment, particularly for safety demonstration of the design of nuclear power plants (NPPs). The objective of deterministic safety analysis is to confirm that safety functions can be fulfilled and that the necessary structures, systems and components, in combination with operator actions, are effective in keeping the releases of radioactive material from the plant below acceptable limits. Deterministic safety analysis, supplemented by further specific information and analysis, including probabilistic safety analysis, is also intended to demonstrate that the source term and the potential radiological consequences of different plant states are acceptable, and that the possibility of certain conditions arising that could lead to an early or a large radioactive release can be considered as 'practically eliminated'. The publication has been updated to maintain consistency with current IAEA safety requirements and to reflect lessons from the Fukushima Daiichi accident. It takes into account current practices and experience from deterministic safety analyses for NPPs being performed around the world.

Deterministic safety analysis is an important tool for confirming the adequacy and efficiency of provisions within the defence in depth concept for the safety of nuclear power plants (NPPs). IAEA Safety Standards Series No. NS-R-1.2 and Safety Reports Series No. 23 recommend, as one of the options for demonstrating the inclusion of adequate safety margins, the use of best estimate computer codes with realistic input data in combination with the evaluation of uncertainties in the calculation results. The evaluation of uncertainties is an issue of considerable complexity, and this Safety Report has been developed to complement the existing publications. It provides more detailed information on the methods available for the evaluation of uncertainties in deterministic safety analysis of NPPs and practical guidance in the use of these methods.

The objective of this Safety Guide is to provide harmonized guidance to designers, operators, regulators and providers of technical support on deterministic safety analysis for nuclear power plants. It provides information on the utilization of the results of such analysis for safety and reliability improvements. The Safety Guide addresses conservative, best estimate and uncertainty evaluation approaches to deterministic safety analysis and is applicable to current and future designs.

Dated September 2004. PSA = Probability Safety Assessment

Deterministic safety analysis is an important tool for confirming the adequacy and efficiency of provisions within the defence in depth concept for the safety of nuclear power plants (NPPs). IAEA Safety Standards Series No. NS-R-1.2 and Safety Reports Series No. 23 recommend, as one of the options for demonstrating the inclusion of adequate safety margins, the use of best estimate computer codes with realistic input data in combination with the evaluation of uncertainties in the calculation results. The evaluation of uncertainties is an issue of considerable complexity, and this Safety Report.

Accident analysis is an important tool for confirming the adequacy and efficiency of provisions within the defence in depth concept for the safety of nuclear power plants (NPPs). The purpose of the report is to provide the necessary practical guidance for performing adequate accident analysis in the light of current good practice worldwide.