ML20058M920
| ML20058M920 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 09/29/1993 |
| From: | Wang A Office of Nuclear Reactor Regulation |
| To: | Opeka J CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO. |
| Shared Package | |
| ML20058M925 | List: |
| References | |
| TASK-03-02, TASK-03-04.A, TASK-3-2, TASK-3-4.A, TASK-RR TAC-M51938, NUDOCS 9310070134 | |
| Download: ML20058M920 (5) | |
Text
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WASHINGTON. 0.C. 20555-0001 September 29, 1993 Docket No. 50-213 Mr. John F. Opeka Executive Vice President Nuclear Engineering and Operations Connecticut Yankee Atomic Power Company Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06141-0270
Dear Mr. Opeka:
SUBJECT:
HADDAM NECK PLANT - SYSTEMATIC EVALUATION TOPICS III-2 and III-4.A,
" WIND AND TORNADO LOADINGS AND TORNADO MISSILES" (TAC NO. M51938)
The NRC has completed its review of the Systematic Evaluation Program (SEP)
Topics III-2 and III-4.A, " WIND AND TORNADO LOADINGS AND TORNADO MISSILES,"
for the Haddam Neck Plant. The purpose of this topic was to review the plant against the criteria of General Design Criterion (GDC) 2, as implemented by SRP Sections 3.3.1 and 3.3.2 and Regulatory Guides (RG) 1.70 and 1.117, to determine if the plant has the ability to withstand the effects of wind and tornado loadings including tornado missiles. The SEP review concluded that i
the existing design of some structures and components important to safety wauld not meat current licensing criteria regarding the ability of safety-related structures and components to resist tornado winds of 300 mph and differential pressures of 2.25 psi. By letter dated June 3, 1988, Connecticut Yankee Atomic Power Company (CYAPCO) proposed to resolve this SEP topic by demonstrating an adequate resistance for tornado loadings and tornado missiles based on a probabilistic risk assessment combined with a cost benefit analysis to idertify modifications to achieve a core melt frequency (CMF) commensurate with (AF values for other external phenomena at the Haddam Neck Plant. CYAPC0 propcsed to use the TORMIS Code methodology to perform a tornado wind and missile risk analysis. This approach would consist of the following five tasks:
1.
A system failure review of the feed and bleed and auxiliary feedwater safe shutdown systems would be performed. This review would include:
- 1) identifying all system components required to ensure the plant can be brought to hot shutdown, 2) identifying the required instrumentation and control for each component, 3) system failure logic, and 4) identifying the required function of each component within the system.
2.
Perform a site-specific tornado analysis to generate a tornado data set for the TORMIS analysis.
3.
Perform a failure modes analysis for each component in each shutdown system. These failure modes will take into account the tornado effects of missile impact, dynamic pressure, and atmospheric pressure change.
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i Mr. John F. Opeka September 29, 1993 4.
Develop the TORMIS methodology to estimate the probability of damage to the Haddam Neck Plant structures and components from extreme winds.
5.
A cost-benefit analysis will be performed to determine the most cost effective modifications.
By letter dated October 11, 1988, the staff reviewed this approach and agreed that this approach was reasonable for closing the SEP topic.
In addition, by letter dated September 18, 1993, the Commission concluded that plants with construction permits issued prior to May 21, 1971, do not need exemptions from t
the GDC. The Commission stated that "While compliance with the intent of the GDC is important, each plant licensed before the GDC were formally adopted was evaluated on plant specific basis, determined to be safe, and licensed by the Commission."
t By letter dated July 11, 1991, CYAPC0 provided the results of a risk reduction analysis which determined six potential modifications to reduce the consequences of a tornado initiated events. Of these six potential modifications, CYAPC0 has implemented one (separation of loads from MCC-5) and committed to another (new auxiliary feedwater (AFW) pump) but has since determined that it is not cost beneficial to tornado proof the pump.
By letter dated June 30,1993, CYAPC0 provided the results of its tornado analysis. CYAPC0 states that the initial analysis performed in 1989 determined a CMF due to tornado initiated accident sequences of 7.6E-5/ year.
The probabilistic analysis was updated to include system design changes, analytical modeling changes and upgrades made to the plant since 1989. The design changes include implementation of the new switchgear building, separation of loads from MCC-5, and addition of a new condensate storage tank.
Using the revised plant system modeling, the current tornado CMF was found to be 5.7E-5/ year. CYAPC0 has analyzed the remaining four. initiatives and has concluded that the single most beneficial modification that can be made to decrease the CMF due to tornadoes is the addition of an air-cooled diesel.
This modification provides a diverse source of emergency AC which is independent of service water and will reduce the CHF by as much as 40%, to a final CMF value for tornado winds and missiles as low as 3.4E-5/ year.
By letter dated September 14,1993, CYAPC0 provided the results of a sensitivity study for the remaining modifications in the risk reduction study to reduce the CMF for tornado initiated events. Based on this submittal, the staff agrees with CYAPC0 that further incremental reductions in the CHF (< 1.0E-5/ year) would require increasingly large capital expenditures and are deemed not to be cost effective.
r By "B14579, Revises 930609 Response to Violation Noted in Insp Rept 50-213/93-04.Informs That Alternative Test Method Identified & Implemented Per GL 89-04 for Rapid Acting Valves.Stroke Time Test Results for SVs [[procedure" contains a listed "[" character as part of the property label and has therefore been classified as invalid. & CH-SOV-242B Encl|letter dated August 23, 1993]], CYAPCO provided the staff a comparison of the CMF due to tornadoes at the Haddam Neck Plant site with the CMF for other external events at the Haddam Neck Plant site.
CYAPC0 is updating completed probabilistic risk assessments (PRAs) for internal Flooding and Fires and has calculated CMF values of 1.0E-5/ year and 5.0E-5/ year, respectively.
In addition, CYAPC0 is calculating CMF values for seismic and external flooding.
j The best estimate so far for these CMF values are that they will be between i
September 29, 1993 Mr. John F. Opeka
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1.0E-4/ year and 1.0E-5/ year. The staff has compared the CMF due to tornadoes at the Haddam Neck Plant site with the CMF for tornadoes at other sites. The tornado initiated numbers available for comparison were taken from NUREG/CR-5042, " Evaluation of External Hazards to Nuclear Power Plants in the United States." CMF values for four plants of similar vintage were available. While the comparison may not be directly applicable because of differences in assumptions, methodology, and compilation of the tornado data set, it does indicate that the Haddam Neck CMF for tornado initiated events falls in between the four plants (higher than two units and lower than two units).
In addition, Abnormal Operating Procedure (A0P) 3.2-5, " Natural Disasters,"
will provide some compensatory actions should a tornado strike or if a tornado warning is declared.
If a tornado strike were to occur at the plant, the operators would initiate E-0, " Reactor Trip or Safety Injection" which would shutdown the plant.
If a tornado warning is declared actions taken by this procedure would include, but are not limited to, elevating awareness of plant personnel to a potential tornado strike, securir.? and moving under cover loose material and equipment, initiate actions to expecite restoration of any-important plant equipment out of service, checking levels of various safety related tanks, support or strongback Turbine Hall roll-up doors and other tasks that prepare the plant to mitigate the consequences of a tornado. While tornadoes are not as trackable or predictable as hurricanes, this A0P will provide for some actions to minimize the effects of a tornado and confirm the plant's ability to mitigate the potential consequences of a tornado.
The staff has concluded that the analysis is acceptable and that the CMF numbers calculated for tornado initiated events at the Haddam Neck Plant are representative of the plant. The calculated CHF for tornado initiated events at the Haddam Neck site is commensurate with CMF values for other external chenomena at the Haddam Neck site and other plants of similar vintage.
In addition, CYAPC0 has made an assessment of the hardening and upgrade options for the plant and determined that the only remaining cost beneficial modification is the addition of the air-cooled diesel. The plant will take some compensatory actions should a tornado strike or a tornado warning be declared.
Based on the above, the staff concludes CYAPC0 has demonstrated the ability to withstand the effects of wind and tornado loadings including tornado missiles. While the Haddam Neck Plant would not meet current Standard Review Plan criteria, the staff has concluded that the Haddam Neck Plant, with the proposed air-cooled diesel and the current AFW and feed and bleed systems can safely withstand the effects of wind and tornado loadings including tornado missiles and meets the intent of the GDCs.
The staff considers SEP Topics III-2 and II-4.A complete.
Enclosed is the staff Safety Evaluation of the Tornado Probabilistic Risk Assessment of the Haddam Neck Plant.
Mr. Jahn F. Opeka September 29, 1993 -
i If you have any questions regarding this matter, please contact me at (301)504-1445.
Sincerely, Original signed by:
Alan Wang, Project Manager Project Directorate I-4 Division of Reactor Projects - I/II Office of Nuclear Regulatory Commission T
Enclosure:
Safety Evaluation cc w/ enclosure:
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Mr. John F. Opeka-
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If you have any questions regarding this matter, please contact me at
.(301)504-1445.
.i Sincerely, Ch Lday Alan Wang, Project Manager Project Directorate I-4 Division of Reactor Projects - I/II Office of Nuclear Regulatory Comission
Enclosure:
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Safety Evaluation cc w/encicou A:
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b i:: ej Mr. John F. Opeka Haddam Neck Plant Northeast Nuclear Energy Company cc:
Gerald Garfield, Esquire R. M. Kacich, Director Day, Berry and Howard Nuclear Licensing Counselors at Law Northeast Utilities Service Company City Place Post Office Box 270 Hartford, Connecticut 06103-3499 Hartford, Connecticut 06141-0270 W. D. Romberg, Vice President S. E. Scace, Vice President Nuclear Operations Services Millstone. Nuclear Power Station Northeast Utilities Service Company Northeast Nuclear Energy Company Post Office Box 270 Post Office Boy 128 Hartford, Connecticut 06141-0270 Waterford, Connecticut 06385 Kevin T. A. McCarthy, Director Regional Administrator Monitoring and Radiation Division Region I Department of Environmental Protection U.S. Nuclear Regulatory Commission 79 Elm Street 475 Allendale Road Post Office Box 5066 King of Prussia, Pennsylvr.nia 19406 Hartford, Connecticut 06102-5066 Allan Johanson, Assistant Director Board of Selectmen Office of Policy and Management Town Office Building Policy Development and Planning Division Haddam, Connecticut 06438 80 Washington Street Hartford, Connecticut 06106 Resident Inspector Haddam Neck Plant' J. P. Stetz, Vice-President c/o U.S. Nuclear Regulatory Commission Haddam Neck Plant 361 Injun Hollow Road Connecticut Yankee Atomic Power Company East Hampton, Connecticut 06424-3099 362 Injun Hollow Road East Hampton, Connecticut 06424-3099 Nicholas S. Reynolds Winston & Strawn D. J. Ray 1400 L Street, NW Haddam Neck Unit Director Washington, DC 20005-3502 Connecticut Yankee Atomic Power Company 362 Injun Hollow Road East Hampton, Connecticut 0647.4-3099 J. M. Solymossy, Director Nuclear Quality and Assessment Services Northeast Utilities Service Company Post Office Box 270 Hartford, Connecticut 06141-0270 t
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