Evaluation of severe accident risks: Methodology for the containment, source term, consequence ...

283 Pages·2003·13.09 MB·English

NUREGfCR-4551
SAND864309
Vol. 1, Rev. 1
Evaluation of
Severe Accident Risks:
Methodology for the Contaimnent,
Source Term, Consequence, and
Risk Integration Analyses
Prepared by
E. D. Gorham, R. J. Breeding, J. C. Helton, T D. Brown,
W. B. Murfin, E T. Harper, S. C. Hora
Sandia National Laboratories
Operated by
Sandia Corporation
Prepared for
U.S. Nuclear Regulatory Commission
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NuREG/CR-4551
SAND864309
Vol. 1=, Re v. 1
AN¶
Evaluation of
Severe Accident Risks:
Methodology for the Containment,
Source Term, Consequence, and
Risk Integration Analyses
Manuscript Completed: October 1993
Date Published: December 1993
Prepared by
E. D. Gorham, R. J. Breeding, J. C. Helton', T. D. Brown,
W. B. Murfinz, E "Harper, S. C. Horn3
Sandia National Laboratories
Albuquerque, NM 87185-5800
Prepared for
Division of Safety Issue Resolution
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
NRC FIN A1322
State University, Tempe, AZ 85287
Tkchnadyne Engineering Consultants, Inc., Albuquerque, NM, 87112
Wniversity of Hawaii, Hilo, HI 96720-4091
..
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OF THIS1 -cD OCUMENT IS UNLIMITED

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ABSTRACT
NUREG-1150 examines the risk to the public from five nuclear power plants. The
NUREG-1150 plant studies are Level I11 probabilistic risk assessments (PRAs) and,
as such, they consist of four analysis components: accident frequency analysis,
accident progression analysis, source term analysis, and consequence analysis.
This volume summarizes the methods utilized in performing the last three
components and the assembly of these analyses into an overall risk assessment.
The NUREG-1150 analysis approach is based on the following ideas: (1) general and
relatively fast-runningm odels for the individual analysis components, (2) well-
defined interfaces between the individual analysis components, (3) use of Monte
Carlo techniques together with an efficient sampling procedure to propagate
uncertainties, (4) use of expert panels to develop distributions for important
phenomenological issues, and (5) automation of the overall analysis. Many
features of the new analysis procedures were adopted to facilitate a
comprehensive treatment of uncertainty in the complete risk analysis.
Uncertainties in the accident frequency, accident progression and source term
analyses were included in the overall uncertainty assessment. The uncertainties
in the consequence analysis were not included inthis assessment. Alarge effort
was devoted to the development of procedures for obtaining expert opinion and the
execution of these procedures to quantify parameters and phenomena for which
there is large uncertainty and divergent opinions in the reactor safety
community.
iii

TABLE OF CONTENTS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FOREWORD xi
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACKNOWLEDGMENTS xv
. . . . . . . . . . . . . . . . . . . . . . . .
ACRONYMS AND INITIALISMS mii
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.0 INTRODUCTION 1.1
. . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Background 1.1
. . . . . . . . . . . . .
1.2 Objectives of the NUREG-1150 Study 1.2
. . . . . . . . . . . . . . . . .
1.3 Quality Control and Reviews 1.4
. . . . . . . . . . . . . . . . .
1.4 Organization of this Volume 1.6
. . . . . . . . . . . . . . . . . . . . . . . . .
1.5 References 1.7
. . . . . . . . . . . . . . . .
2.0 REPRESENTATION OF RISK IN NUREG-1150 2.1
. . . . . . . . . . . . . . . . . . .
2.1 Representation of Risk 2.1
. . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 References 2.3
. . . . . . . . . . .
3.0 IDEAS UNDERLYING THE COMPUTATIONAL FRAMEWORK 3.1
. . . . . . . . .
3.1 General and Relatively Fast-Running Models 3.1
. . . . . . . . . . . . . . . . . . .
3.2 Well-Defined Interfaces 3.3
. . . . . . . . . . . . . . . . . . .
3.3 Monte Carlo Techniques 3.5
. . . . . . . . . . . . . . . . . . .
3.4 Use of Expert Panels 3.7
. . . . . . . . . . . . . . .
3.5 Automation of Overall Analysis 3.7
. . . . . . . . . . . . . . . . . . . . . . . . .
3.6 References 3.10
. . . . . . . . . . . . .
4.0 STRUCTURE OF THE NUREG-1150 PLANT STUDIES 4.1
. . . . . . . . . . . . . . . . .
4.1 Accident Frequency Analysis 4.1
. . .
4.2 Accident Progression and Containment Response Analysis 4.4
. . . . . . . . . . . . . . . . . . . .
4.3 Source Term Analysis 4.5
. . . . . . . . . . . . . . . . . . . .
4.4 Consequence Analysis 4.7
. . . . . . . . . . . . . . . .
4.5 Propagation of Uncertainties 4.10
. . . . . . . . . . . . . . . . . . . . .
4.6 Calculation of Risk 4.16
. . . . . . . . . . . . . . . . . . . . . . . . .
4.7 References 4.18
5.0 INTERFACE OF ACCIDENT SEQUENCE FREQUENCY ANALYSIS WITH
. . . . . . . . . . . . . . . . .
THE ACCIDENT PROGRESSION ANALYSIS 5.1
. . . . . . . . . . . . . . . . . . . . . . . .
5.1 Introduction 5.1
. . . . . . . . . . . . . . . . . . . . . .
5.2 Initiating Events 5.1
. . . . . . . . . . . . . . . . .
5.3 Accident Sequence Analysis 5.2
. . . . . . . . . . . . . . . . . . . . .
5.4 Plant Damage States 5.8
. . . . . . . . . . . . . . . . . .
5.5 Core Vulnerable Sequences 5.10
. . . . . . . . . .
5.6 Products of the Accident Frequency Analysis 5.10
. . . . . . . . . . . . . . . . . . . . . . . . .
5.7 References 5.16
. . . . . .
6.0 ACCIDENT PROGRESSION AND CONTAINMENT RESPONSE ANALYSIS 6.1
. . . . . . . . . . . . . . . . . . . . . . . .
6.1 Introduction 6.1
. . . . .
6.2 Description of the Accident Progression Event Trees 6.2
. . . . . . . . .
6.3 Quantification and Evaluation of the APETs 6.7
. . . . . . . . . . . . . . .
6.4 Grouping of Event Tree Outcomes 6.8
V
TABLE OF CONTENTS (continued)
. . . . . . . . . .
6.5 Products of Accident Progression Analysis 6.12
. . . . . . . . . . . . . . . . . . . . . . . . .
6.6 References 6.20
. . . . . . . . . . . . . . . . . . . . . . .
7.0 SOURCE TERMANALYSIS 7.1
. . . . . . . . . . . . . . . . . . . . . . . .
7.1 Introduction 7.1
. . . . . . . . . . . . .
7.2 Decomposition of Release Fractions 7.3
. . . . . . . . . . . .
7.3 Development of Source Term Data 13ase 7.6
7.4 Mapping from Accident Progression Bins to Source Term Data
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Base 7.7
. . . . . . . . . . . . . . . . . . . . . . .
7.5 TheXSORCodes 7.8
. . . . . . . . . . . . . . . . . .
7.6 Source Term Partitioning 7.9
. . . . . . . . . . . . . . . . . .
7.7 Source Term Risk Results 7.10
. . . . . . . . . . . . . . . . . . . . . . . . .
7.8 References 7.13
. . . . . . . . . . . . . . . . . . .
8.0 OFFSITE CONSEQUENCE ANALYSIS 8.1
. . . . . . . . . . . . . . . . . . . . . . . .
8.1 Introduction 8.1
. . . . . . . . . . .
8.2 Assessment of Pre-Accident Inventories 8.1
8.3 Transport, Dispersion, and Deposition of Radioactive
. . . . . . . . . . . . . . . . . . . . . . . . . .
Material 8.2
. . . . . . . . . . . . . . . . . . . .
8.4 Calculation of Doses 8.3
. . . . . .
8.5 Mitigation of Doses by Emergency Response Actions 8.3
. . . . . . . . . . . . . . . . . . .
8.6 Health Effects Modeling 8.4
. . . . . . . .
8.7 Products of Offsite Consequence Analysis
. . . . . . . . . . . . . . . . . . . . . . . . . 8.5
8.8 References 8.8
. . . . .
9.0 CHARACTERIZATION AND COMBINATION OF UNCERTAINTIES . . . .
9.1
. . . . . . . . . . . . . . . . . . . . . .
9.1 Overview . . . .
9.1
. . . . . . . . . . . . . . . .
9.2 Types of Uncertainty . . . .
9.5
. . . . . . . . . . . . . . .
9.3 Use of Expert Opinion . . . .
9.7
. . . . . . . . .
9.3.1 Steps to Elicit Expert Judgment 9.8
. . . . . . . . . . . . . . .
9.3.2 Selection of Issues 9.8
. . . . . . . . . . . . . .
9.3.3 Selection of Experts 9.15
. . . . . . . . . . . . . .
9.3.4 Elicitation Training 9.15
. . . . . . . . . . . . . . . . .
9.3.5 Training Topics 9.15
9.3.6 Presentation of Issues . . . . . . . . . . . . . 9 .16
. . . . .
9.3.7 Preparation and Discussion of Analyses 9.17
. . . . . . . . . . . . . . . . . . . .
9.3.8 Elicitation 9.17
. . . .
9.3.9 Recomposition and Aggregation of Results 9.17
. . . . . . . . . . . . . . . . .
9.3.10 Review . . . . 9 .18
9.3.11 Documentation . . . . . . . . . . . . . . . . . . 9 .18
. . . . . . . . . . . . . . . . . . . . .
9.4 References . . . . 9 .19
APPENDIX A DESCRIPTION OF SUITE OF CODES USED TO CALCULATE
RISK
. . . . . . . . . . . . . . . . . . . . . . . .
A.l Introduction A.l
. . . . . . . . . . . . . . . . .
A.2 Input From Level I Analysis A.l
. . . . . . . . . . . . . . . . . . .
A.3 Latin Hypercube Sample A.6
. . . . . . . . . . . . . . . . .
A.4 Accident Progression Analysis A.7
. . . . . . . . . . . . . . . . . . . .
A.5 Source Term Analysis A.9
vi