MARVIN RAUSAND Risk Assessment Theory, Methods, and Applications STATISTICS I:-\ PRACTICE
RISK ASSESSMENT
STATISTICS IN PRACTICE Advisory Editor Wolfgang Jank University of Maryland, USA Founding Editor Vic Barnett Nottingham Trent University, UK The texts in the series provide detailed coverage of statistical concepts, methods, and worked case studies in specific fields of investigation and study. With sound motivation and many worked practical examples, the books show in down-to-earth terms how to select and use an appropriate range of statistical techniques in a particular practical field. Readers are assumed to have a basic understanding of introductory statistics, enabling the authors to concentrate on those techniques of most importance in the discipline under discussion. The books meet the need for statistical support required by professionals andresearch workers across a range of employment fields and research environments. Subject areas covered include medicine and pharmaceutics; industry, finance, and commerce; public services; the earth and environmental sciences. A complete list of titles in this series appears at the end of the volume.
RISK ASSESSMENT Theory, Methods, and Applications MARVIN RAUSAND Norwegian University of Science and Technology ~WILEY A JOHN WILEY & SONS, INC., PUBLICATION
Cover photo credit: Helge Hansen/Statoil Copyright 2011 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section I 07 or I 08 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., Ill River Street, Hoboken, NJ 07030, (20 I) 748-60 II, fax (20 I ) 7 48-6008, or online at http://www. wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging-in-Publication Data: Rausand, Marvin. Risk assessment : theory, methods, and applications I Marvin Rausand. p. em.- (Statistics in practice) Includes index. ISBN 978-0-470-63764-7 (hardback)' I Technology-Risk assessment. 2. Risk assessment. I. Title. TI74.5.R37 2011 363.1 '02-dc22 2011010971 Printed in the United States of America. 10 9 8 7 6 5 4 3 2 I
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CONTENTS Preface Acknowledgments PART I INTRODUCnON TO RISK ASSESSMENT XIII xvil 1 Introduction 3 1.1 Introduction 3 1.2 Risk Analysis, Assessment, and Management 7 1.3 The Study Object 12 1.4 Accident Categories 15 1.5 Risk in Our Modem Society 17 1.6 Safety Legislation 19 1.7 Risk and Decision-Making 21 1.8 Structure of the Book 27 1.9 Additional Reading 28 vii
viii CONTENTS 2 The Words of Risk Analysis 29 2.1 Introduction 29 2.2 Events and Scenarios 30 2.3 Probability and Frequency 33 2.4 Assets and Consequences 41 2.5 Risk 45 2.6 Barriers 54 2.7 Accidents 56 2.8 Uncertainty 58 2.9 Vulnerability and Resilience 59 2.10 Safety and Security 61 2.11 Additional Reading 63 3 Hazards and Threats 65 3. I Introduction 65 3.2 Ha7.ards 66 3.3 Classi cation of Hazards 70 3.4 Threats 71 3.5 Energy Sources 72 3.6 Technical Failures 74 3.7 Human and Organizational Factors 76 3.8 Additional Reading 76 4 How to Measure and Evaluate Risk 77 4.1 Introduction 77 4.2 Risk Indicators 78 4.3 Risk to People 79 4.4 Risk Matrices 99 4.5 Risk Acceptance Criteria 106 4.6 Closure 115 4.7 Additional Reading 115 5 Risk Management 117 5.1 Introduction 117 5.2 Risk Management 117 5.3 Bow-Tie Analysis 119 5.4 Risk Analysis 121
CONTENTS lx 5.5 Risk Evaluation 132 5.6 Risk Control and Risk Reduction 133 5.7 Competence Requirements 134 5.8 Quality Requirements 134 5.9 Additional Reading 136 6 Accident Models 137 6.1 Introduction 137 6.2 Accident Causation 139 6.3 Accident Models 141 6.4 Energy and Barrier Models 144 6.5 Sequential Accident Models 147 6.6 Epidemiological Accident Models 153 6.7 Event Causation and Sequencing Models 160 6.8 Systemic Accident Models 166 6.9 Additional Reading 176 7 Data for Risk Analysis 177 7.1 Introduction 177 7.2 Types of Data 178 7.3 Accident Data 180 7.4 Component Reliability Data 183 7.5 Human Error Data 191 7.6 Software Failure Data 193 7.7 Expert Judgment 193 7.8 Data Dossier 194 7.9 Additional Reading 194 PART II RISK ASSESSMENT METHODS AND APPLICATIONS 8 Risk Assessment Process 199 8.1 Introduction 199 8.2 Plan and Prepare 201 8.3 Reporting 206 8.4 Updating 210 8..5 Additional Reading 211
X CONTENTS 9 Hazard ldentl cation 213 9.1 Introduction 213 9.2 Hazard Log 216 9.3 Checklist Methods 219 9.4 Preliminary Hazard Analysis 223 9.5 Change Analysis 232 9.6 FMECA 236 9.7 HAZOP 246 9.8 SWIFT 256 9.9 Master Logic Diagram 262 9.10 Additional Reading 263 10 Causal and Frequency Analysis 265 10.1 Introduction 265 10.2 Cause and Effect Diagram Analysis 267 10.3 Fault Tree Analysis 271 10.4 Bayesian Networks 294 10.5 Markov Methods 304 10.6 Petri Nets 316 10.7 Additional Reading 335 11 Development of Accident Scenarios 337 11.1 Introduction 337 11.2 Event Tree Analysis 339 11.3 Event Sequence Diagrams 359 11.4 Cause-Consequence Analysis 359 11.5 Escalation Problems 360 11.6 Consequence Models 361 11.7 Additional Reading 362 12 Barriers and Barrier Analysis 363 12.1 Introduction 363 12.2 Barriers and Barrier Classi cation 364 12.3 Barrier Properties 370 12.4 Safety Instrumented Systems 372 12.5 Hazard-Barrier Matrices 382 12.6 Safety Barrier Diagrams 383
CONTENTS xl 12.7 Bow-tie Diagrams 384 12.8 Energy Flow/Barrier Analysis 385 12.9 Layer of Protection Analysis 388 12.10 Barrier and Operational Risk Analysis 397 12.11 Additional reading 407 13 Human Reliability Analysis 409 13.1 Introduction 409 13.2 Task Analysis 420 13.3 Human Error ldenti cation 427 13.4 HRA Methods 434 13.5 Additional Reading 456 14 Job Safety Analysis 457 14.1 Introduction 457 14.2 Objectives and Applications 457 14.3 Analysis Procedure 458 14.4 Resources and Skills Required 466 14.5 Advantages and Limitations 467 14.6 Additional reading 467 15 Common-Cause Failures 469 15.1 Introduction 469 15.2 Basic Concepts 470 15.3 Causes of CCFs 474 15.4 Modeling of CCFs 476 15.5 The Beta-factor Model 480 15.6 More Complex CCF Models 486 15.7 Additional Reading 495 16 Uncertainty and Sensitivity Analysis 497 16.1 Introduction 497 16.2 Uncertainty 499 16.3 Categories of Uncertainty 500 16.4 Contributors to Uncertainty 502 16.5 Uncertainty Propagation 507 16.6 Sensitivity Analysis 512
xil CONTENTS 16.7 Additional Reading 513 17 Development and Applications of Risk Assessment 17.1 Introduction 17.2 Defense and Defense Industry 17.3 Nuclear Power Industry 17.4 Process Industry 17.5 Offshore Oil and Gas Industry 17.6 Space Industry 17.7 Aviation 17.8 Railway Transport 17.9 Marine Transport 17.10 Machinery Systems 17.11 Other Application Areas 17.12 Closure 515 515 517 518 522 526 528 530 532 534 536 537 541 PART Ill APPENDICES Appendix A: Elements of Probability Theory A.l Introduction A.2 Outcomes and Events A.3 Probability A.4 Random Variables A.5 Some Speci c Distributions A.6 Point and Interval Estimation A.7 Bayesian Approach A.8 Probability of Frequency Approach A.9 Additional Reading Appendix 8: Acronyms 545 545 546 550 555 562 571 575 577 583 585 Appendix C: Glossary 593 References 608 Index 635
Preface This book gives a comprehensive introduction to risk analysis and risk assessment, and the main methods for such analyses. It deals with accidents that may occur in technical or sociotechnical systems with focus on sudden, major accidents. Day-today occupational accidents and negative health effects due to long-term exposure are therefore outside the scope of the book. In I 99 I, the Norwegian standard NS 5814, Requirements to Risk Analysis, was issued and I wrote a small book in Norwegian called Risk Analysis: Guidance to NS 58/4 (Rausand, 1991). The book was very basic but filled a purpose and was used extensively. I began to write the current book in 1995 after the first edition of the book System Reliability Theory was published. After awhile I realized that writing a book on risk assessment was much more difficult than writing a book on system reliability. This was due mainly to the confusing terminology, the multidisciplinary character of the topics, and the overwhelming number of reports and guidelines that had been written. In 2008, the second edition of NS 5814 was issued and the guideline had to be updated and extended. This resulted in the book Risk Analysis: Theory and Methods (Rausand and Utne, 2009b), which is written in Norwegian and coauthored by Ingrid Bouwer Utne. The book was strongly influenced by the manuscript of the current book, has a similar structure, but is more basic and straightforward. XIII