Evaluation of Quantification of Margins and Uncertainties Methodology for Assessing and Certifying the Reliability of the Nuclear Stockpile (2009)

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Evaluation of Quantification of Margins and Uncertainties Methodology for Assessing and Certifying the Reliability of The Nuclear Stockpile Committee on the Evaluation of Quantification of Margins and Uncertainties Methodology for Assessing and Certifying the Reliability of the Nuclear Stockpile Division on Engineering and Physical Sciences 

THE NATIONAL ACADEMIES PRESS  500 Fifth Street, N.W.  Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Gov- erning Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engi- neering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This project was supported by Contract No. DE-AT01-07NA78285 between the National Academy of Sciences and the U.S. Department of Energy. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the organizations or agencies that provided support for this project. International Standard Book Number-13: 978-0-309-12853-7 International Standard Book Number-10: 0-309-12853-6 Copies of the unclassified version of this report are available from The National Academies Press 500 Fifth Street, N.W. Box 285 Washington, DC 20055 800-624-6242 202-334-3313 (in the Washington metropolitan area) Internet http://www.nap.edu Copyright 2009 by the National Academy of Sciences. All rights reserved. Printed in the United States of America 

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Committee on Evaluation of Quantification of Margins and UncertaintIES Methodology for Assessing and Certifying the Reliability of the Nuclear Stockpile JOHN F. AHEARNE (NAE), Sigma Xi, The Scientific Research Society, Chair MARVIN ADAMS, Texas A&M University JOHN CORNWALL, University of California, Los Angeles DOUGLAS EARDLEY, University of California, Santa Barbara B. JOHN GARRICK (NAE), Independent Consultant RICHARD L. GARWIN (NAS/NAE/IOM), IBM Thomas J. Watson Research Center (fellow emeritus) SYDELL P. GOLD, Independent Consultant YOGENDRA GUPTA, Washington State University DAVID HAMMER, Cornell University THEODORE HARDEBECK, Science Applications International Corporation JOHN KAMMERDIENER, Independent Consultant SALLIE KELLER-McNULTY, Rice University ERNEST J. MONIZ, Massachusetts Institute of Technology MICHAEL ORTIZ, California Institute of Technology JERRY PAUL, University of Tennessee ROBERT ROSNER, Argonne National Laboratory ROBERT SELDEN, Independent Consultant Staff RICHARD ROWBERG, Study Director GREG EYRING, Senior Program Officer, Air Force Science Board MICAH LOWENTHAL, Senior Program Officer, Nuclear and Radiation Studies Board KEVIN CROWLEY, Board Director, Nuclear and Radiation Studies Board MARGARET MARSH HUYNH, Senior Program Assistant, Computer Science and Telecommunications Board (to September 2007) JANICE SABUDA, Senior Program Assistant, Computer Science and Telecommunications Board (September 2007 to March 2008)   Deceased, March 4, 2008.  

RADHIKA CHARI, Administrative Coordinator, Computer Science and Telecommunications Board (March 2008 to April 2008) ERIC WHITAKER, Senior Program Assistant, Computer Science and Telecommunications Board (April 2008 to present) vi 

Preface Maintaining the capabilities of the nuclear weapons stockpile and performing the annual assessment for the stockpile’s certification involves a wide range of processes, technologies, and expertise. An important and valuable element helping to link those components is the quantification of margins and uncertainties (QMU) framework. In 2006, Congress asked the National Research Council to evaluate the QMU methodology as used by the national security laboratories. The National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE) then affirmed its interest in this request. Congress and NNSA were interested in how the national security labs were using QMU, how it was being used for the annual assessment, whether there were problematic differences among the three national security labs in the way they were applying QMU, and whether QMU could be used to help certify a proposed reliable replacement warhead. This report presents an assessment of each of these four issues and includes findings and recommendations to help guide laboratory and NNSA implementation and development of the QMU framework and congressional oversight of those activities. At several places in the report, reference is made to an Annex that contains classified information. The Annex includes information the U.S. Department of Energy and the National Academy of Sciences have deter- mined is not releasable to the public because it would disclose matters described in title 5 U.S.C. Section 552(b). vii 



Acknowledgments This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with pro- cedures approved by the NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integ- rity of the deliberative process. We wish to thank the following individu- als for their review of this report: Will Happer (NAS), Princeton University, Jon Helton, Arizona State University (retired), Raymond Jeanloz (NAS), University of California, Berkeley, ADM Richard Mies, U.S. Navy (retired), William Press (NAS), University of Texas at Austin Richard Wagner, Lawrence Livermore National Laboratory (retired), and Ellen Williams (NAS), University of Maryland. Although the reviewers listed above have provided many construc- tive comments and suggestions, they were not asked to endorse the con- clusions or recommendations, nor did they see the final draft of the report before its release. The review of this report was overseen by Chris G. ix 

 ACKNOWLEDGMENTS Whipple (NAE), ENVIRON. Appointed by the National Research Council, he was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring com- mittee and the institution. 

Contents SUMMARY 1 1 OVERVIEW 4 Introduction, 4 Context, 4 Issues, 6 Statement of Task, 7 Background, 9 Definition and Current Implementation of QMU, 9 Study Process, 16 2 USE OF THE QMU METHODOGY (Task 1) 18 Uncertainty Quantification, 20 Uncertainty Propagation and Aggregation, 21 Sources of Uncertainty, 23 Representation of a Simple Performance Gate, 25 Introducing More Complex Probability Distributions, 26 Direct Computation of Distribution Overlap, 28 Phenomenology of Nuclear Explosions, 30 Role of Modeling and Simulation in QMU, 31 3 QMU AND THE ANNUAL ASSESSMENT 34 REVIEW (Task 2) Sandia National Laboratories, 35 xi 

xii CONTENTS Los Alamos National Laboratory, 36 Lawrence Livermore National Laboratory, 36 Performance Gates, 37 Peer Review Opportunities, 37 4 COMPARISON AND CONTRAST OF THE USE 39 OF QMU (Task 3) 5 QMU AND THE RRW PROGRAM (Task 4) 43 APPENDIXES A A Probabilistic Risk Assessment Perspective of QMU 51 B Committee Biographical Information 67 C Glossary 77