ML18094A900
| ML18094A900 | |
| Person / Time | |
|---|---|
| Issue date: | 03/13/2018 |
| From: | Thomas Wellock NRC/SECY |
| To: | |
| Moulton C | |
| References | |
| Download: ML18094A900 (20) | |
Text
Quantifying Reactor Accident Risk: A History Panel W20: The Metamorphosis to a More Risk-Informed Regulator Tom Wellock NRC
Risk-Informed, Performance-Based
- A New Paradigm
- Efficiency
- Safety Significant
- Relieve Regulatory Burden
- PRAs: Significant Limitations
- Industry-NRC gap
- Methodology
- Data
- Peer Review
- New Safety Issues NRC Chairman Shirley Jackson 2
Three Ds of the Deterministic Era
- Deterministic Design
- Design Basis Accidents
- Defense-in-Depth
- Inherent Safety
- Active Systems
- Siting
- Static Layers (containment) 3
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WASH-1400 and the Roots of PRA Methodology: Models and Goals in the 1960s Regulatory Necessity Political Necessity 5
6 Accident Modeling in the 1960s
Farmer Curve 7
Chauncey Starr
- Loss of Coolant and the China Syndrome
- ECCS
- Beyond the Design Basis Accident
- Need for regulatory risk expertise New Safety Issues 8
AEC Under Siege
- Anti-nuclear Movement
- Class 9 accidents.
- Growing interest in risk
- Congress Henry Kendall, UCS 9
WASH-1400: Positives
- New tool for regulators
- A spectrum of accidents
- Core damage more likely but lower consequences 10
Small LOCA Event Tree from WASH-1400 11
WASH-1400: Negatives
- Large error bands
- Inappropriate comparisons to other risks
- Some accidents not analyzed
- Lacked adequate peer review
- Lewis Committee (1978) 12
13 WASH-1400, Executive Summary
14 UCS Critique of WASH-1400
Three Mile Island and WASH-1400 Human factors and operations Severe accidents Safety systems other than ECCS 15 TMI Control Room, March 1979
1980s: Beneficially Unfocused
- Beyond the Design Basis: ATWS, SBO, severe accidents
- Unresolved Questions: Generic issues, older plants
- Operating Reactors: Evaluating events
- New Reactors: Design certification
- Methodology: Industry PRAs and NUREG-1150
- Goals: Safety Goal Policy and Backfits 16
Toward Risk-Informed Regulation, 1990s Individual Plant Examinations Towers-Perrin Report Maintenance Rule PRA Policy Statement (1995) and Implementation Plan (1994) 17
References Slide 2: U.S. NRC, An Evening with Dr. Shirley Ann Jackson, November 15, 1995, U.S. NRC ADAMS Main Library, ML003710152.
Slide 4: C.A. Bennett to A.B. Greninger, Evaluation of Probability of Disasters, HW-28767, July 20, 1953, DOE Public Reading Room Catalog, Accession #
D8451637.
Slide 6: P.A. Crosetti and R.F. Furrer, Comparative Reliability AnalysisK-Reactor Secondary Coolant System, DUN-4461 (Hanford, WA: Douglas United Nuclear, September 9, 1968), U.S. Department of Energy Opennet,,https://www.osti.gov/opennet/detail.jsp?osti-id=16413875; B.J.
Garrick, Reliability Analysis of Nuclear Power Plant Protective Systems, HN-190, May 1967, (Los Angeles: Holmes & Narver, May 1967); R.S. Hart and W.T. Harper, Final SNAPSHOT Safeguard Report, NAA-SR-10022(Rev.) (San Diego, CA:
Atomics International, March 20, 1965).
Slide 7: F.R. Farmer, Siting CriteriaA New Approach, Containment and Siting of Nuclear Power Plants, Proceedings of a Symposium, Vienna 3-7 April 1967 (Vienna: International Atomic Energy Agency, 1976) 322; Chauncey Starr, Social Benefit vs. Technological Risk, Science 165 no. 3899, September 19, 1969, 1232-38.
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References (cont.)
Slide 9: Archive of the Norfolk Charitable Trust, Sharon, MA.
Slides 11 and 13: U.S. NRC, Reactor Safety Study: An Assessment of Accident Risks in U.S. Commerical Nuclear Power Plants, WASH-1400 (NUREG-75/014) (DC:
U.S. NRC, October 1975).
Slide 14: Sierra Club and Union of Concerned Scientists, Preliminary Review of the AEC Reactor Safety Study (San Francisco-Cambridge, December 1974),
100B.
Slide 15: TMI Control Room in 1979, U.S. NRC Flickr, https://www.flickr.com/photos/nrcgov/7447591188/in/album-72157628998200797/.
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Acronyms ATWS: Anticipated Transient Without Scram ECCS: Emergency Core Cooling System PRA: Probabilistic Risk Assessment SBO: Station Blackout UCS: Union of Concerned Scientists WASH: AEC Headquarters, Washington, DC 20