Probabilistic Safety Assessment Of Wwer440 Reactors

The aim of this book is to summarize probabilistic safety assessment (PSA) of nuclear power plants with WWER440 reactors and demonstrate that the plants are safe enough for producing energy even in light of the Fukushima accident. The book examines level 1 and 2 full power, low power and shutdown PSA, and summarizes the author’s experience gained during the last 35 years in this area. It provides useful examples taken from PSA training courses the author has lectured and organized by the International Atomic Energy Agency. Such training courses were organised in Argonne National Laboratory (Chicago, IL, USA), Abdus Salaam International Centre for Theoretical Physics (Trieste, Italy), Malaysia, Vietnam and Jordan to support experts from developing countries. The role of PSA for the plants is an estimation of the risks in absolute terms and in comparison with other risks of the technical and the natural world. Plant-specific PSAs are being prepared for the plants and being applied for detection of weaknesses, design improvement and backfitting, incident analysis, accident management, emergency preparedness, prioritization of research and development and to support the regulatory activities. There are three levels of PSA, being performed for full power and low power operation and shutdown operating modes of the plants: level 1, 2 and 3 PSA. The nuclear regulatory authorities do not require the level 3 PSA for the plants in the member countries of the European Union. This means that only a limited number of NPPs in Europe have the level 3 PSA available. However, in the light of the Fukushima accident the performance of such analyses is strongly recommended in the future. This book is intended for professionals working in the nuclear industry, researchers and students interested in safety of operational plants.

This safety report establishes guidelines on the role that probabilistic safety assessment can play as part of an overall safety assurance programme in nuclear power plants. It also describes a framework for probabilistic safety criteria (PSC) and provides guidance for the establishment of PSC values.

Presents a practical approach for incorporating human reliability analysis (HRA) into probabilistic safety assessment (PSA). This document describes the steps needed and the documentation that should be provided both to support the PSA itself and to ensure effective communication of important information arising from the studies.

Probabilistic methods are increasingly being used to complement deterministic methods in assessing the safety and ensuring the reliability of research reactors. Addressing features specific to research reactors, this publication suggests a practical approach for the development and implementation of a project using probabilistic methods in terms of objective, scope, data and modelling, as well as the application of results to enhance safety and reliability. This publication is intended to be used by operating organizations, regulatory bodies and technical support organizations when performing or reviewing research reactor assessments in which probabilistic methods are applied. It will ideally be read in conjunction with relevant IAEA Safety Standards Series publications and technical guidelines for safety analysis, operation and maintenance, and component reliability data for research reactors.

Provides an approach for achieving the technical consistency of probabilistic safety assessments (PSAs) needed to support various PSA applications. The approach involves the consideration of a set of technical features, called attributes, of the major PSA elements relevant for various applications.

This report is a guide for designers, operators and regulatory bodies responsible for evaluating the potential consequences of a large primary to secondary leakage accident in WWER-440 reactors. Specific attention is paid to the modelling of such an accident and to resulting safety issues.

The technical approach described in this publication builds on the use of a single unit probabilistic safety assessment (PSA) and identifies considerations that are needed from the multi-unit perspective. This is the first attempt to expand the current PSA process to take account of multi-unit issues, and has been done by distilling lessons learned from the Fukushima Daiichi accident and other multi-unit events, and by reviewing previous PSAs and supporting research that have addressed the risks of multi-unit accidents. The publication provides a roadmap and methodology for performing a multi-unit PSA, proposes a set of site level risk metrics, and presents examples of approaches to resolve specific issues.

This book describes a number of the more important improvements in risk assessment methodology in the nuclear industry, developed over the last decade. It presents them in an instructive way so as to be suitable for those wishing to understand the techniques. The methodology of modern probabilistic risk assessment (PRA) is discussed in detail. This book is divided into six parts. Part I, Protecting the Public Health and Safety provides an overview of risk analysis including results presentation, safety goals, emergency planning, and public perception. Part II, the Mathematics, which is necessary to understand the text. Part III, safety Aspects of Light Water Reactors describes the types of plants and goes on to discuss accident initiator selection and frequencies. Part IV, PRA, describes system modelling, human factors analysis, data bases, codes, system interactions, external events, core melt physics, and the transport of radionuclides to the public. Part V discusses 34 types of applications of PRA. Part VI, Resources, provides a glossary, references, and an index. Problems are provided at the end of each part to both stimulate understanding and introduce additional material. This book would be a very valuable addition to the reference library of practitioners in the risk assessment business. It is also a useful instructional text for graduate and undergraduate nuclear engineering students as well as newcomers to the field.