Precursors to Potential Severe Core Damage Accidents: 1998

227 Pages·2005·10.89 MB·English

NUREG/CR-4674
ORNL/NOAC-232
Vol. 27
Precursors to Potential
Severe Core Damage
Accidents: 1998
A Status Report
Oak Ridge National Laboratory
U.S. Nuclear Regulatory Commission
Office of Nuclear Regulatory Research
Washington, DC 20555-0001
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NUREG/CR-4674
ORNL/NOAC-232
Vol. 27
Precursors to Potential Severe
Core Damage Accidents: 1998
A Status Report
Manuscript Completed: June 2000
Date Published: July 2000
Prepared by
R-J. Belles, J.W. Cletcher, D.A. Copinger, B.W. Dolan',
J.W. Minarick', M.D. Muhlheim, P.D. O'Reilly', S. Weerakkody',
H. Hamzehee2
Oak Ridge National Laboratory
Managed by UT-Battelle, LLC
Oak Ridge, TN 37831-6285
Division of Safety Analysis Applications
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
NRC Job Code B0435
'Science Appicatlons Internmatiomal Corporation. Oak Ridge, TN 37831
'U.S. Nuclear Regulatory Comunlalon, Washington, DC 20555-0001
PREVIOUS REPORTS IN THE SERIES
1. J. W. Minarick and C. A. Kukielka, Union Carbide Corp., Nuclear Div., Oak Ridge Natl. Lab.; and Science
Applications, Inc., Precursorst o PotentialS evere Core Damage Accidents: 1969-1979, A Status Report,
USNRC Report NUREG/CR-2497 (ORNL/NSIC-1 82N/1 and V2), June 1982.
2. W. B. Cottrell, J. W. Minarick, P. N. Austin, E. W. Hagen, and J. D. Harris, Martin Marietta Energy
Systems, Inc., Oak Ridge Natl. Lab.; and Science Applications International Corp., Precursorst o Potential
Severe Core Damage Accidents: 1980-81, A Status Report, USNRC Report NUREG/CR-359 1, Vols. I
and 2 (ORNL/NSIC-217NVI and V2), July 1984.
3. J. A. Forester, J. W. Minarick, H. K. Schriner, B. W. Dolan, D. B. Mitchell, D. W. Whitehead, and J. J.
Jansen, Sandia Natl. Lab.; and Science Applications International Corp., Precursorst o PotentialS evere
Core Damage Accidents: 1982-83, A Status Report, USNRC Report NUREG/CR-4674, Vol. 24
(SAND97-0807), April 1997.
4. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Natl. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1984, A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 3 and 4),
May 1987.
5. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Nati. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1985, A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 1 and 2),
December 1986.
6. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Nat!. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1986, A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 5 and 6),
May 1988.
7. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Nat!. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1987, A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 7 and 8),
July 1989.
8. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Natl. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1988,A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 9 and 10),
February 1990.
9. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Natl. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1989, A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 11 and
12), August 1990.
i NUREG/CR-4674, Vol. 27
10. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Natl. Lab.; Science Applications
International Corp.; and Professional Analysis, Inc., Precursors to Potential Severe Core Damage
Accidents: 1990, A Status Report, USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 13 and
14), August 1991.
11. J. W. Minarick et al., Martin Marietta Energy Systems, Inc., Oak Ridge Natl. Lab.; and Science Applications
International Corp., Precursors to PotentialS evere Core Damage Accidents: 1991, A Status Report,
USNRC Report NUREG/CR-4674 (ORNL/NOAC-232, Vols. 15 and 16), September 1992.
12. D. A. Copinger et al., Martin Marietta Energy Systems, Inc., Oak Ridge Natl. Lab.; and Science Applications
International Corp., Precursorst o Potential Severe Core Damage Accidents: 1992, A Status Report,
USNRC Report NUREG/CR-4674 (ORNLJNOAC-232, Vols. 17 and 18), December 1993.
13. L. N. Vanden Heuvel, J. W. Cletcher, D. A. Copinger, J. W. Minarick, and B. W. Dolan, Martin Marietta
Energy Systems, Inc., Oak Ridge Natl. Lab.; and Science Applications International Corp., Precursorst o
Potential Severe Core Damage Accidents: 1993, A Status Report, USNRC Report NUREG/CR-4674
(ORNL/NOAC-232,Vols. 19 and 20), September 1994.
14. R. J. Belles, J. W. Cletcher, D. A. Copinger, B. W. Dolan, J. W. Minarick, and L. N. Vanden Heuvel,
Lockheed Martin Energy Systems, Inc., Oak Ridge Nail. Lab.; and Science Applications International Corp.,
Precursors to Potential Severe Core Damage Accidents: 1994, A Status Report, USNRC Report
NUREG/CR-4674 (ORNL/NOAC-232, Vols. 21 and 22), December 1995.
15. R- J. Belles, J. W. Cletcher, D. A. Copinger, B. W. Dolan, J. W. Minarick, and M. D. Muhlheim, Lockheed
Martin Energy Research, Inc., Oak Ridge Natl. Lab.; and Science Applications International Corp.,
Precursors to Potential Severe Core Damage Accidents: 1995, A Status Report, USNRC Report
NUREG/CR-4674 (ORNL/NOAC-232, Vol. 23), April 1997.
16. R1J . Belles, J. W. Cletcher, D. A. Copinger, B. W. Dolan, J. W. Minarick, and M. D. Muhlheim, Lockheed
Martin Energy Research, Inc., Oak Ridge Natl. Lab.; and Science Applications International Corp.,
Precursors to Potential Severe Core Damage Accidents: 1996, A Status Report, USNRC Report
NUREG/CR-4674 (ORNIUNOAC-232, Vol. 25), December 1997.
17. R. J. Belles, J. W. Cletcher, D. A. Copinger, B. W. Dolan, J. W. Minarick, and M. D. Muhlheim, Lockheed
Martin Energy Research, Inc., Oak Ridge Natl. Lab.; and Science Applications International Corp.,
Precursors to Potential Severe Core Damage Accidents: 1997, A Status Report, USNRC Report
NUREG/CR-4674 (ORNL/NOAC-232, Vol. 26), December 1998.
ii
NNUURREEGG//CCRR--44667744,, VVooll.. 2277 ii
Abstract
This report describes the nine operational events in 1998 that affected eight commercial light-water reactors
(LWRs) and that are considered to be precursors to potential severe core damage accidents. All these events had
conditional probabilities of subsequent severe core damage greater than or equal to 1.0 x 10-. These events were
identified by first computer-screening the 1998 licensee event reports from commercial LWRs to identify those
events that could be precursors. Candidate precursors were selected and evaluated in a process similar to that used
in previous assessments. Selected events underwent an engineering evaluation to identify, analyze, and document
the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar
evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters to
ensure that the plant design and its response to the precursor were correctly characterized. This study is a
continuation of earlier work that evaluated 1969-1997 events. The report discusses the general rationale for this
study, the selection and documentation of events as precursors, and the estimation of conditional probabilities
of subsequent severe core damage for the events.
NUREG/CR-4674, Vol. 27
i°°i°i NUREG/CR-4674, Vol. 27
Contents
Previous Reports in Series .............................................................. i
Abstract ............................................................................ iii
list of Figures ........................................................................ vii
list of Tables ......................................................................... viU°
Preface ............................................................................ i,
Foreword ............................................................................ Xi
Acknowledgments ..................................................................... xiii
list of Acronyms ...................................................................... xv
1. Introduction ...................................................................... 1-1
1.1 Background ................................................................. 1-1
1.2 Current Process ............................................................. 1-1
2. Selection Criteria and Quantification ................................................. 2-1
2.1 Accident Sequence Precursor Selection Criteria .................................. 2-1
2 .1.1 P recursors ............................................................ 2-1
2.1.2 Potentially Significant Events Considered Impractical to Analyze ................. 2-4
2.1.3 Containment-Related Events ............................................. 2-4
2.1.4 "Interesting" Events ..................................................... 2-5
2.2 Precursor Quantification ...................................................... 2-5
2.3 Review of Precursor Documentation ............................................ 2-6
2.4 Precursor Documentation Format .............................................. 2-6
2.5 Potential Sources of Error ..................................................... 2-8
v NUREG/CR-4674, Vol. 27
3. Results ........................................................................... 3-1
3.1 Tabulation of Precursors ...................................................... 3-2
3.1.1 Potentially Significant Events That Were Impractical to Analyze ................. 3-5
3.1.2 Containm ent-Related Events .............................................. 3-5
3.1.3 "Interesting" Events ..................................................... 3-5
3.2 Insights ..................................................................... 3-6
3.2.1 Number of Precursors Identified .................................... 3-6
3.2.2 Im portant Precursors ............................................. 3-12
3.2.3 LOOP-Related Precursors ......................................... 3-13
3.2.4 Consistency with PRAs/IPEs ..................................... 3-14
3.2.5 BW R vs PWR ................................................. 3-14
3.2.6 Mu ltiunit Site vs Single Unit Site .................................. 3-15
3.2.7 Electric Power-Related Events .................................... 3-16
3.2.8 Feedwater-Related Events ........................................ 3-17
3.2.9 Safety-Related High / Low Pressure Systems ......................... 3-18
3.3 Conclusion .......................................................... 3-19
4. G lossary .................................................................. 4-1
5. References ................................................................ 5-1
Appendices
Appendix A: ASP Calculational Methodology .................................. A. 1-1
Appendix B: At-Power Precursors for 1998 ..................................... B. 1-1
Appendix C: Shutdown Precursors for 1998 ..................................... C. 1-1
Appendix D: "Impractical" Events ............................................ D. 1-1
Appendix E: Containment-Related Events ...................................... E. 1-1
Appendix F: "Interesting" Events ............................................. F. 1-1
Appendix G: Resolution of Comments for 1998 Precursor Analyses ................. G. 1-1
vi
NNUURREEGG//CCRR--44667744,, VVooll.. 2277 Vi
List of Figures
Figure Page
Fig. 2.1 A SP analysis process .............................................................. 2-2
Fig. 2.2 A SP review process ............................................................... 2-7
Fig. 3.1 Total number of precursors by year ................................................... 3-6
Fig. 3.2 Number of precursors resulting from unavailabilities ..................................... 3-7
Fig. 3.3 Number of precursors resulting from initiating events ..................................... 3-7
Fig. 3.4 Contributors to precursors resulting from initiating events .................................. 3-7
Fig. 3.5 Contributors to precursors ......... ............................................... 3-8
Fig. 3.6 CCDP results by year for 103 to 1.0 .................................................. 3-10
Fig. 3.7 CCDP results by year for 10' to 10.. ................................................. 3-10
Fig. 3.8 CCDP results by year for l10 to 10. ................................................. 3-11
Fig. 3.9 CCDP results by year for 10' to 10.. ................................................. 3-11
Fig. 3. 10 Number of important precursors .................................................... 3-12
Fig. 3.11 Number of LOOP-related precursors per year ......................................... 3-13
Fig. 3.12 Number of precursors occurring at BWRs ............................................. 3-15
Fig. 3.13 Number of precursors occurring at PWRs ............................................. 3-15
Fig. 3.14 Percentage of precursors at multiunit sites ............................................. 3-15
Fig. 3.15 Number of electric-power-related precursors .......................................... 3-16
Fig. 3.16 Contributors to electric-power related precursors ....................................... 3-16
Fig. 3.17 Number of AFW/EFW-related precursors associated with unexpected demands ............... 3-17
Fig. 3.18 Contributors to AFW/EFW-related precursors ......................................... 3-17
Fig. 3.19 Number of precursors involving failed high-pressure / low-pressure recirculation/injection ...... 3-18
Fig. 3.20 Contributors to high-pressure / low-pressure recirculation/'mjection system failures ........... 3-18
vii NUREG/CR-4674, Vol. 27
List of Tables
Table Page
Table 3.1 At-Power Precursors Involving Initiating Events Sorted by Event Identifier ................... 3-3
Table 3.2 At-Power Precursors Involving Unavailabilities Sorted by Event Identifier .................... 3-3
Table 3.3 At-Power Precursors Involving Initiating Events Sorted by CCDP .......................... 3-4
Table 3.4 At-Power Precursors Involving Unavailabilities Sorted by Importance ....................... 3-4
Table 3.5 Index of "Containment-Related" Events ............................................... 3-5
Table 3.6 Index of "Interesting" Events ........................................................ 3-6
Table 3.7 Failure M odes of Precursors ......................................................... 3-8
Table 3.8 Num ber of Precursors by Year ....................................................... 3-9
Table 3.9 Precursors w ith a CCD P 2 10.. ..................................................... 3-13
Table 3.10 Precursors not Typically Modeled in PRAs or IPEs ..................................... 3-14
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NUREG/CR-4674, Vol. 27 Viii