ML18214A397
| ML18214A397 | |
| Person / Time | |
|---|---|
| Issue date: | 07/22/2018 |
| From: | Hossein Nourbakhsh Advisory Committee on Reactor Safeguards |
| To: | |
| Nourbakhsh H | |
| References | |
| Download: ML18214A397 (23) | |
Text
ACRS' ENDURING LEGACY CONTRIBUTING TO REACTOR SAFETY Hossein Nourbakhsh Senior Technical Advisor for Reactor Safety Office of the Advisory Committee on Reactor Safeguards (ACRS)
U.S. Nuclear Regulatory Commission Presented at the 26th International Conference on Nuclear Engineering (ICONE 26)
London, England, July 22-26, 2018
Outline
- A brief history of ACRS
- Role of ACRS over its history
- Licensing Reviews
- Regulatory Policies and Practices
- Operating Reactors Safety Oversight
- Safety Research Reviews
- Nuclear Materials and Waste
- Summary & Conclusion 2
The Birth of ACRS
- In 1947, the AEC recognized the need for an independent technical group to review and provide advise on reactor safety matters and thus a Reactor Safeguard Committee was established.
Edward Teller
- In 1950, AEC established a second advisory committee, Industrial Committee on Reactor Location Problems.
- In 1953, the Reactor Safeguard Committee and the Industrial Committee on Reactor Location Problems were combined by the AEC and and the ACRS was formally born C. Rogers McCullough 3
ACRS - History AEC forms Reactor Safeguards Committee Industrial Committee on Reactor Location Problems is established The two Committees are combined into ACRS 1957 Amendment to the Atomic Energy Act of 1954 establishes the ACRS as a Statutory Committee Advising the AEC Enactment of the Energy Reorganization Act transferred the ACRS intact from AEC to NRC 1950 1960 1970 1980 1990 2000 2010 Shippingport AEC is established ACNW&M functions are returned to ACRS Chicago Critical Pile Commission established ACNW (re-named ACNW&M in 2007)
NRC is established 4
ACRS Review Activities During Its History 300 Number of Letters/Reports 250 200 150 100 50 0
1950s 1960s 1970s 1980s 1990s 2000s 2010-2016 Years Licensing Reviews Rulemaking Activities and Development of Guidance Documents Operating Reactors Safety Oversight Safety Research Reviews Nuclear Materials and Waste 5
Licensing Reviews
- The ACRS has played an important role in licensing reviews of reactors.
- The ACRS early reviews led to evolution of many new safety requirements.
- Control rod ejection accidents (ACRS was first to raise the issue in 1964)
- The need for improved ECCS
- Anticipated Transients Without Scram (issue was raised by an ACRS consultant in 1969)
- Seismic design considerations including effects of a tsunami following a major earthquake 6
Need for Improved ECCS
- In 1960s, the ACRS challenged the major vendors to include improved ECCS designs for utility licensing applications.
- By the summer of 1966 General Electric responded in support of the Dresden 3 plant. They introduced a redundant core-flooding system and an automatic depressurization system.
- Later that year Westinghouse introduced accumulators.
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Seismic Design Considerations - Effects of a Tsunami Following A Major Earthquake
- During early 1960s, ACRS reviewed several proposed power reactor locations in southern California including sites proposed by the City of Los Angles.
- The ACRS review of the proposal of the City of Los Angles to construct and operate a 1473 MWt PWR, Malibu Nuclear Plant Unit 1, at Corral Canyon (twenty-nine miles west of Los Angles) is particularly noteworthy
- The issue of effects of a tsunami following a major seismic event was discussed for the first time during this review.
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ACRS Report on Proposed 1473 MWt Malibu Nuclear Plant (July 15, 1964)
The ability of the plant to withstand the effects of a tsunami following a major earthquake has been discussed with the applicant. There has not been agreement among consultants about the height of water to be expected should a tsunami occur in this area. The Committee is not prepared to resolve the conflicting opinions, and suggests that intensive efforts be made to establish rational and consistent parameters for this phenomenon. The applicant has stated that the containment structure will not be impaired by inundation to a height of fifty feet above mean sea level. The integrity of emergency in-house power supplies should also be assured by location at a suitable height and by using water-proof techniques for the vital power system. The emergency power system should be sized to allow simultaneous operation of the containment building spray system and the recirculation and cooling system. Ability to remove shutdown core heat under conditions of total loss of normal electrical supply should be assured. If these provisions are made, the Committee believes that the plant will be adequately protected.
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Regulatory Policies and Practices
- The ACRS has played a significant role in shaping the regulatory policies and practices of the NRC
- Emergency Planning: In 1966, pressed by the ACRS, the AEC undertook a study of emergency plans and procedures that eventually led to a new Appendix E to !0 CFR part 50, Emergency Planning and Preparedness for Production and Utilization Facilities.
- Quantitative Safety Goals: The ACRS was at forefront of the development of quantitative safety goals. The first set of trial goals (NUREG-0739) was developed by the ACRS in 1980.
- Risk-informed Regulations and Practices: The ACRS has been very supportive of the evolution toward a risk-informed and performance-based regulatory system and had technical oversight of this transformation.
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Operating Reactors Safety Oversight
- The ACRS has always been attentive to safety improvements in operation of nuclear power plants.
- Was first to recommend periodic comprehensive (10 year) review of operating power reactors in 1966
- Significant contribution toward resolution of many generic safety issues
- Deliberations regarding the role and effectiveness of the NRC Reactor Oversight Process (ROP) in monitoring organizational performance 11
Safety Research Reviews
- Throughout its history, an essential activity of the ACRS has also been reviewing the research sponsored by the agency.
- Review of research conducted in support of specific regulatory activities
- Episodic review of particularly important ongoing research
- Review of the technical and programmatic aspects of the overall safety research program
- Review of the quality of selected research projects (since 2004) 12
Safety Research Reviews (Continued)
- During its early licensing reviews, the ACRS identified many technical safety issues for further research
- Early attention to potential radiation damage to reactor pressure vessel
- Early concerns about core meltdown accidents 13
Early Concerns about Severe Accidents
- By the mid 1960s, as proposed plants increased significantly in size, the ACRS became concerned that a core meltdown accident could lead to a breach of containment
- At the prodding of ACRS, the AEC established a special task force to look into the problem of core meltdown in 1966. The task force, chaired by William K. Ergen, a former ACRS member, issued its report in October 1967.
- The report offered assurances about the improbability of a core meltdown, and the reliability of ECCS designs, but it also acknowledged that LOCA could cause a breach of containment if the ECCS failed to perform.
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ACRS Letter on The Task Force Report (February 26, 1968)
- Strongly recommended that a positive approach be adopted toward studying the workability of protective measures to cope with core meltdown
- Recommended, as it did in its 1966 report on safety research, that a vigorous program be aimed at gaining better understanding of the phenomena and mechanisms important to the course of large-scale core meltdown 15
Response to Ergen Report and ACRS Recommendations
- The task force report and ACRS recommendations formed the basis of some of the most important research initiatives and regulatory decisions by the AEC and the NRC
- ECCS rulemaking on system acceptance criteria
- AECs decision to undertake a study to estimate the probability of a severe accident (WASH-1400) 16
Nuclear Materials and Waste
- Before the establishment of ACNW in 1988, ACRS Reviewed matters related to the long term management of radioactive wastes produced within the nuclear industry.
- Since the merging of ACNW&M into ACRS in 2008, the Committee has been reviewing many aspects of nuclear waste management such as handling, processing, transportation, and storage.
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Some of the most significant successes of the Nuclear Regulatory Commission were achieved in large part with the benefit of the wise counsel perhaps even the prodding - of the ACRS Excerpt from a speech by former NRC Chairman Richard Meserve Before a symposium honoring the 50th anniversary of the ACRS (March 4, 2003) 18
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