ML19011A440
| ML19011A440 | |
| Person / Time | |
|---|---|
| Issue date: | 01/16/2019 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| Nathan Siu 415-0744 | |
| Shared Package | |
| ML19011A416 | List:
|
| References | |
| Download: ML19011A440 (24) | |
Text
Risk-Informed Fire Protection Lecture 8-3 1
Key Topics
- Browns Ferry fire
- Fire PRA history
- Risk-informed fire protection
- Current controversies 2
Overview
Resources U.S. Nuclear Regulatory Commission, The Browns Ferry Nuclear Plant Fire of 1975 Knowledge Management Digest, NUREG/KM-0002, Rev. 1, February 2014.
S.P. Nowlen, M. Kazarians, and F. Wyant, Risk Methods Insights Gained From Fire Incidents, NUREG/CR-6738, September 2001.
N. Siu, N. Melly, S. P. Nowlen, and M. Kazarians, Fire Risk Assessment for Nuclear Power Plants, The SFPE Handbook of Fire Protection Engineering, 5th Edition, Springer-Verlag, New York, 2016.
Nuclear Energy Agency, CSNI Technical Opinion: Fire Probabilistic Safety Safety Assessment for Nuclear Power Plants: 2019 Update, Boulogne-Billancourt, France, in publication.
N. Siu, K. Coyne, and N. Melly, Fire PRA maturity and realism: a technical technical evaluation, U.S. Nuclear Regulatory Commission, March 2017.
(ADAMS ML17089A537) 3 Overview
Other References U.S. Code of Federal Regulations, Fire Protection, 10 CFR 50.48, June 16, 2004, last amended Aug. 28, 2007.
National Fire Protection Association, Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants, NFPA 805, 2001 Edition, Quincy, MA, 2001. (Available through the NFPA Online Catalog at www.nfpa.org)
Electric Power Research Institute and U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research, EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities, EPRI 1011989 and NUREG/CR-6850, Electric Power Research Institute (EPRI), Palo Alto, CA and U.S. Nuclear Regulatory Commission, Washington, DC, 2005.
Electric Power Research Institute and U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research, Fire Probabilistic Risk Assessment Methods Enhancements: Supplement 1 to NUREG/CR-6850 and EPRI 1011989, EPRI 1019259 and NUREG/CR-6850 Supplement 1, Electric Power Research Institute (EPRI), Palo Alto, CA and U.S. Nuclear Regulatory Commission, Washington, DC, 2009.
4 Overview
Other References (cont.)
M. Kazarians, N. Siu, and G. Apostolakis, Fire risk analysis for nuclear power plants:
methodological developments and applications, Risk Analysis, 5, 33-51, 1985.
N. Siu, J.T. Chen, and E. Chelliah, Research Needs in Fire Risk Assessment, NUREG/CP-0162, Vol. 2, 25th Water Reactor Safety Information Meeting Bethesda, MD, October 20-22, 1997.
U.S. Nuclear Regulatory Commission, Perspectives Gained from the Individual Plant Examination of External Events (IPEEE) Program, NUREG-1742, April 2002.
Nuclear Energy Agency, International Workshop on Fire PRA: Workshop Proceedings, NEA/CSNI/R(2015)12, Boulogne-Billancourt, France, 2015. (Available from:
http://www.oecd-nea.org/nsd/docs/indexcsni.html)
B. McGrattan, et al., Fire Protection and Fire Research Knowledge Management Digest, 2013, NUREG/KM-0003, 2013.
N. Siu, Fire Risk Assessment for Nuclear Power Plants, FPE 580R - Fire Risk Assessment and Policy, Worcester Polytechnic Institute, December 2, 2015. (ADAMS ML15301A832)
N. Siu, PSA Heterogeneity: Implications for Risk Aggregation, IAEA Consultancy Meeting on Development of a Methodology for Aggregation of Various Risk Contributors for Nuclear Facilities, International Atomic Energy Agency, Vienna, Austria, April 10-13, 2017. (ADAMS ML17093A744) 5 Overview
Risk-Informed Regulations 6
How it started Browns Ferry Nuclear Power Plant (3/22/75)
Candle initiated cable tray fire; water suppression delayed; complicated shutdown Second-most challenging event in U.S. nuclear power plant operating history Spurred changes in requirements and analysis 7
8.5m 11.5m 3m Adapted from NUREG-0050 Browns Ferry Fire
Browns Ferry (March 22, 1975) 8 Browns Ferry Fire
Fire Protection After Browns Ferry Post-Browns Ferry deterministic fire protection (10 CFR Part 50, App R) hour fire barrier, OR
- 20 feet separation with detectors and auto suppression, OR hour fire barrier with detectors and auto suppression Concerns
- Equivalence of protection methods:
whats best? foot criterion: how protective?
- Possible to make win-win trade-offs?
- License by exemption?
9 From Cline, D.D., et al., Investigation of Twenty-Foot Separation Distance as a Fire Protection Method as Specified in 10 CFR 50, Appendix R, NUREG/CR-3192, 1983.
Browns Ferry Fire
Professor George Apostolakis, UCLA (UCLA School of Engineering)
Early Fire PRAs Early cable spreading room analyses
- WASH-1400
- HTGR PRA NRC-sponsored, post-Browns Ferry R&D at UCLA => fire PRA methodology
- Physical model for fire-induced damage
- Incorporation in PRA via competing processes model (growth vs.
suppression)
Used and refined in Zion and Indian Point PRAs Framework and tools for subsequent analyses (NUREG-1150, IPEEEs) 10 Fire PRA/RIDM History
Early Results - Fire Can Be Important Or Even Dominant Contributor to CDF 11 Fire PRA/RIDM History
Near Misses - Empirical Support for Results 12 Event Summary Description*
Browns Ferry (BWR, 1975)
Multi-unit cable fire; multiple systems lost, spurious component and system operations; makeup from CRD pump Greifswald (VVER, 1975)
Electrical cable fire; station blackout (SBO), loss of all normal core cooling for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, loss of coolant through valve; recovered through low pressure pumps and cross-tie with Unit 2 Beloyarsk (LWGR, 1978)
Turbine lube oil fire, collapsed turbine building roof, propagated into control building, main control room (MCR) damage, secondary fires; extinguished in 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br />; damage to multiple safety systems and instrumentation.
Armenia (VVER, 1982)
Electrical cable fire (multiple locations), smoke spread to Unit 1 MCR, secondary explosions and fire; SBO (hose streams), loss of instrumentation and reactor control; temporary cable from emergency diesel generator to high pressure pump Chernobyl (RBMK, 1991)
Turbine failure and fire, turbine building roof collapsed; loss of generators, loss of feedwater (direct and indirect causes); makeup from seal water supply Narora (PHWR, 1993)
Turbine failure, explosion and fire, smoke forced abandonment of shared MCR; SBO, loss of instrumentation; shutdown cooling pump energized 17 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br /> later
- See NUREG/CR-6738 (2001), IAEA-TECDOC-1421 (2004)
Fire PRA/RIDM History
Risk-Informed Fire Protection (NFPA 805)
Difficulties with deterministic compliance with Appendix R => exemptions Risk-informed approach Alternative method for regulatory compliance Additional benefits: improved understanding of sources of fire risk, Risk-informed, performance-based fire protection (10 CFR 50.48(c), NFPA 805)
- Voluntary alternative to Appendix R
- Deterministic and performance-based elements
- Changes can be made without prior approval; risk must be acceptable 13 Fire PRA/RIDM History Making Sausage Standard and regulatory approach development Consensus process Multiple stakeholders, diverse views (incl. strong PRA critics)
Good enough for immediate problem 10 CFR 50.48(c)(3)
Fire PRA R&D Restarted in 1997
- Better understanding of fire risk
- Improved support of regulatory activities
- Methods and tools Near-and long-term issues, e.g.,
- Multiple spurious operations
- Lessons from operational events Fire risk requantification task (to assess impact of methodological improvements) => guidance development (joint with EPRI) to support NFPA 805 Major disruption: 9/11 14 NUREG/CR-6850/EPRI TR1011989 Fire PRA/RIDM History
Fire R&D: The Laundry List (c. 1998) 15 Fire PRA/RIDM History
Fire PRAs - More Recent Results 16 Fire PRA/RIDM History
Fire PRAs - Risk Contributors 17 From: K. Voelsing, EPRI Fire PRA Research Plan, U.S. Nuclear Regulatory Commission Regulatory Information Conference, March 15, 2018.
Fire PRA/RIDM History
Recap: Fire PRA/RIDM in the U.S.
18 1975 1980 1990 1985 1995 2000 2010 2005 2015 Browns Ferry fire (WASH-1400 analysis)
Fire PRA R&D IPEEEs Industry Full-Scope PRAs NUREG-1150/RMIEP NFPA 805 LARs NFPA 805, 10 CFR 50.48(c),
RG 1.205, NEI 04-02, EPRI 1011989/NUREG/CR-6850, Fire PRA/RIDM History
A Heated Debate Is fire PRA mature? Are the results overly conservative?
Industry concerns
- Expense of detailed analyses
- Realism of specific sub-models
- Flexibility in making plant changes
- Implications for other risk-informed applications NRC concerns
- Technical basis for alternative models
- Implications for other risk-informed applications 19 Current Challenges RG 1.174, Revision 3
Common View: The Need for Realism
- Excessive conservatism or optimism can
- Inappropriately focus decision maker attention
- Lead to wasteful or even problematic solutions
- Mask opportunities for other improvements
- Damage stakeholder confidence 20
?
Current Challenges
Current Issues - An Example
- High Energy Arcing Faults (HEAF) in cabinets
- Operational events, e.g.,
- Maanshan (2001)
- Robinson (2010)
- Onagawa (2011)
- Potentially important contributor to fire risk
- Multi-national experimental program 21 Current Challenges
Where are we now?
- Completed transitions to NFPA 805 (> 1/3 fleet)
- Use of fire PRA methods by international organizations
- Cooperative data collection and R&D to address some issues
- Debates over appropriate R&D for others
- Debates over proper aggregation of results from heterogeneous analyses 22 Current Challenges
On Aggregation
- Heterogeneity sources in a practical PRA:
- Multiple technical disciplines
- Different states of knowledge
- Different views on what needs to be and what can be reasonably modeled
- Different views on acceptable modeling approaches
- Different views on treatment of uncertainty
- Limited project resources
- Numerical results need to be provided in context 23 Current Challenges
Comments Multiple technical cultures with varying/divergent views on appropriate use of risk information + need for expediency =>
- Compromise solutions that might not be good enough for other applications
- Different solutions for different technical domains (and technical cultures)
Personal concern: myopic tactics can have short-term success but also social impacts that hurt fundamental, long-term acceptance (let alone support) of PRA and RIDM
- Sound-bite characterization of issues
- Goal-directed R&D (reducing conservatism vs. improving realism)
- Marginalization of stakeholders 24