ML15244A751
| ML15244A751 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/12/1992 |
| From: | Wiens L Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9206250205 | |
| Download: ML15244A751 (20) | |
Text
p.REG~j UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 June 12, 1992 Docket Nos. 50-269, 50-270 and 50-287 LICENSEE:
Duke Power Company FACILITY:
Oconee Nuclear Station, Units 1, 2, and 3
SUBJECT:
SUMMARY
OF JUNE 4, 1992, MEETING ON STATION BLACKOUT RESPONSE FOR THE OCONEE NUCLEAR STATION On June 4, 1992, the NRC staff met with representatives of Duke Power Company (DPC) to discuss issues associated with proposed station blackout (SBO) actions at the Oconee Nuclear Station (ONS). The NRC staff review of the initial DPC SBO submittal determined that it did not meet the requirements of 10 CFR 50.63, with the most significant problem being that the proposal would require evacuating the normal plant control room. DPC had requested a meeting with the staff to discuss their revised response prior to submittal.
Mr. J. W. Hampton, Vice President, ONS, began the presentations by discussing DPC's purpose in requesting the meeting.
Mr. M. Patrick, ONS Compliance Manager, made the remaining presentations, which covered the initial DPC response to SBO, the proposed revised response to SBO, and DPC's response to recommendations in the SBO Safety Evaluation Report. The presentation on the initial SBO proposal included a short video which described the design and capabilities of the Standby Shutdown Facility, which is designated as the Alternate AC source for Oconee. The revised response would modify plant procedures to require stripping non-safety loads from the control batteries in case of an SB0 event, which would allow sufficient battery capacity to maintain control of the plant for the full 4-hour coping duration. Mr.
Patrick also presented results of DPC calculations that showed that areas containing SBO equipment would remain habitable without supplemental ventilation for the full coping duration and that equipment qualification temperatures would not be exceeded. He also stated that DPC would implement a reliability and availability program for the Keowee Hydro units.
After a brief caucus with the NRC staff, Mr. David Matthews, Director, Project Directorate 11-3, stated that, based on the information presented, the revised proposal was responsive to the SBO requirements. However, since the information presented was very general, the formal submittal would require additional details. In particular, the assumptions and calculations in determining the revised battery capacity, including the specific loads which would be shed, would need to be included in the submittal.
Other details specifically requested by the a NRC staff included calculations of control room heat-up, including assumed initial temperatures and any administrative controls to ensure this temperature is not exceeded, and details of the Keowee reliability program. The DPC representatives agreed to these requests and indicated the revised submittal would be submitted by July 1, 1992.
4 9206250205 920612 F
PDR ADOCK 05000269 P
Meeting Summary -
Oconee 2 -
June 12, 1992 Meeting participants are listed in Enclosure 1. Handouts distributed by DPC during the presentation are provided in Enclosure 2.
/s/
L. A. Wiens, Project Manager Project Directorate 11-3 Division of Reactor Projects I/II
Enclosures:
DISTRIBUTION As stated Docket File?
E.JORDAN NRC/LOCAL PDRs B.B.DESAI,RES.INSP cc w/enclosures:
PDII-3 RF G.HUBBARD See next page T.MURLEY/F.MIRAGLIA T.KOSHY J.PARTLOW M.B.SHYMLOCK,RII S.VARGA S.MAZUMDAR G.LAINAS E.J.BROWN D.MATTHEWS H.ORNHSTEIN L.WIENS A.THADANI L.BERRY A.TOALSTON OGC P.GILL F.ROSA G.HOLAHAN ACRS (10)
L.REYES, RH J.WECHSELBERGER,EDO PU-TAM OFC
- PDI P Il3 /PM :PO NAME
- L.BERRY
- L. IENS
- DW EWS DATE : 6/1V/92
- 6/1//92 :6///92 OFFICIAL RECORD COPY Document Name:
C:OCOSBO.MTS
Meeting Summary -
Oconee June 12, 1992 Meeting participants are listed in Enclosure 1. Handouts distributed by DPC during the presentation are provided in Enclosure 2.
L. A. Wiens, Project Manager Project Directorate 11-3 Division of Reactor Projects I/II
Enclosures:
As stated cc w/enclosures:
See next page
Mr. J. W. Hampton Duke Power Company Oconee Nuclear Station cc:
Mr. A. V. Carr, Esquire Mr. M. E. Patrick Duke Power Company Compiance 422 South Church Street Duke Power Company Charlotte, North Carolina 28242-0001 Oconee Nuclear Site P. 0. Box 1439 J. Michael McGarry, III, Esquire Seneca, South Carolina 29679 Winston and Strawn 1400 L Street, NW.
Mr. Alan R. Herdt, Chief Washington, DC 20005 Project Branch #3 U. S. Nuclear Regulatory Commission Mr. Robert B. Borsum 101 Marietta Street, NW. Suite 2900 Babcock & Wilcox Atlanta, Georgia 30323 Nuclear Power Division Suite 525 Ms. Karen E. Long 1700 Rockville Pike Assistant Attorney General Rockville, Maryland 20852 North Carolina Department of Justice Manager, LIS P. 0. Box 629 NUS Corporation Raleigh, North Carolina 27602 2650 McCormick Drive, 3rd Floor Clearwater, Florida 34619-1035 Mr. R. L. Gill, Jr.
Licensing Senior Resident Inspector Duke Power Company U. S. Nuclear Regulatory Commission P. 0. Box 1007 Route 2, Box 610 Charlotte, North Carolina 28201-1007 Seneca, South Carolina 29678 Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, NW. Suite 2900 Atlanta, Georgia 30323 Mr. Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 Office of Intergovernmental Relations 116 West Jones Street Raleigh, North Carolina 27603 County Supervisor of Oconee County Walhalla, South Carolina 29621
ENCLOSURE 1 LIST OF ATTENDEES MEETING WITH DUKE POWER COMPANY, OCONEE STATION BLACKOUT JUNE 4, 1992 NAME ORGANIZATION L. WIENS NRR/PDII-3 D. MATTHEWS NRR/PDII-3 J. M. DAVIS DUKE/OCONEE B. L. (JACK) PEELE DUKE/OCONEE ENGINEERING M. PATRICK DUKE/OCONEE COMPLIANCE R. GILL DUKE/CORPORATE LICENSING D. DEATHERAGE DUKE/OCONEE OPERATIONS R. L. DOBSON DUKE/ELECTRICAL ENGINEER D. M. JAMIL DUKE/ELECTRICAL ENGINEER L. J. AZZARELLO DUKE/MECHANICAL/NUCLEAR ENGR B. B. DESAI NRC/RESIDENT INSPECTOR/OCONEE M. S.L SILLS DUKE/OCONEE ENGINEERING R. P. COLAIANNI DUKE/CORPORATE LICENSING G. HUBBARD NRC/DST/SPLB T. KOSHY NRC/DOEA/EAB M. B. SHYMLOCK NRC/RII.
C. JULIAN NRC/RII S. MAZUMDAR NRC/AEOD E. J. BROWN NRC/AEOD/ROAB H. ORNSTEIN NRC/AEOD/ROAB A. THADANI NRC/DST A. TOALSTON NRC/DST/SELB P. GILL NRC/DST/SELB F. ROSA NRC/DST/SELB G. M. HOLAHAN NRC/DST G. C. LAINAS NRC/DRPE J. HAMPTON DUKE/OCONEE SITE VICE PRESIDENT
ENCLOSURE 2 AGENDA PURPOSE OF MEETING INITIAL RESPONSE TO SBO SUPPLEMENTAL RESPONSE TO SBO RESPONSE TO SBO SER RECOMMENDATIONS DISCUSSION 3
STATION BLACKOUT PURPOSE OF MEETING:
Describe our initial response to the SBO rule and provide the bases for why we felt that this response was acceptable.
Provide supplemental information and responses to the SER recommendations.
Obtain NRC management feedback/concurrence on these responses.
Discussion 4
II.
INITIAL RESPONSE TO SBO:
Initial response was based on using the SSF as an alternate AC (AAC) source SSF Video Man the SSF upon SBO initiation: start diesel, RC M/U
- pump, ASW
- pump, and monitor plant parameters Maintain command and control from normal control room, control secondary heat removal using TD EFDW pump Transfer control to the SSF when TD EFDW pump control is degraded or control rooms becomes uninhabitable Recovery from SBO by procedure 5
A. BASES FOR INITIAL RESPONSE:
- 1) SSF CAPABILITY Designed to provide an alternate and independent means to achieve and maintain hot shutdown conditions for one or more of the three Oconee units Instrumentation and controls allows monitoring and controlling primary and secondary system parameters Operators are trained to utilize the facility NRC has approved use of the SSF for Appendix R Fire, Flood and Sabotage.
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SSF INSTRUMENTATION 5 Incore Thermocouples RCS Loop A&B Pressure (0-2500 psi)
RCS Loop A&B Ilot Leg Temp (0-6000 F)
RCS Loop A&B Cold Leg Temp (0-600' F)
Pressurizer Level (0-400")
Pressurizer Pressure (0-2500 psi)
ASW Unit Total Flow (0-1200 gpi)
SG A&B Levels (0-388")
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- 2) HISTORICAL SSF UNAVAILABILITY YEAR ORIGINAL REVISED
- 1985 2.7%
2.3%
1986 4.3%
3.2%
1987 3.7%
3.2%
1988 3.3%
2.8%
1989 13.0%
11.7%
1989**
N/A 3.6%
1990 3.9%
2.4%
1991 N/A 1.0%
1992 N/A 4.0%
Difference from the original (ie to treatment of operable/standby verses available Unwatering not considered for comparison Historical availability has averaged > 95%
- 3) CORE DAMAGE FREQUENCY - CDF SSF UNAVAILABILITY
& UNRELIABILITY CHANGE IN CDF 5%
Base Case (4E-06) 8%
Increase < IE-06 11%
Increase < I E-06 8
B.
PLANT SPECIFIC PRA Historically, Oconee was one of the plants analyzed under RSSMAP (NUREG/CR-1659) in the late 1970's In 1980, NSAC, in cooperation with Duke Power, initiated a plant-specific PRA of Oconee Unit 3. This study was published in June 1984 as NSAC-60 and has been extensively reviewed by both the NRC and industry.
In 1987, Duke initiated a large scale review and update of the original Oconee PRA. Major objectives of this review and update were:
- 1) Incorporate plant changes made since original study
- 2) Improve on assumptions made in original study
- 3) Incorporate plant specific data from the 1980's
- 4) Make use of improvements in PRA methodology.
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B.
PLANT SPECIFIC PRA (Cont)
The present (updated) Oconee PRA has been submitted to the NRC in response to GL 88-20 and is currently being reviewed by the staff.
Current PRA results show that the Core Damage Frequency (CDF) from an SBO is already < 1E-05 which meets the intent of the SBO rule as stated in NUMARC 87-00 on page 2-5.
BASES OF ORIGINAL RESPONSE:
Use of the SSF met the stated objective of the SBO rule 10
III. SUPPLEMENTAL ACTION:
Modify plant mitigation procedures to strip non-safety loads from the control batteries. This can be accomplished within 30 minutes which is guidance provided in NUMARC 87-00, Section 7.2.2.
Analysis shows that this allows maintaining command and control from the control room for > the full 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping duration.
Instrumentation still remaining following load stripping includes that necessary to monitor primary and secondary parameters:
All RPS Instrumentation All ES Instrumentation Nuclear Instrumentation Emergency FDW Level Control & Indication This will allow us to meet the goal of staying in the control room for the entire 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping duration.
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IV. RESPONSE TO THE SER RECOMMENDATIONS:
A.
Reliability/Availability of the SSF:
- 1) Proposed AC (AAC) Power Source:
The Licensee should make modifications to improve the overall reliability of the SSF system to 95% or better, or provide alternative means for coping with an SBO event.
- 2) Condensate Inventory for Decay Heat Removal:
The licensee should ensure that the water from Lake Keowee will be available to the SSF ASW pump at all times or provide an alternate source of water for coping with an SBO event.
12
DUKE RESPONSE Historically, reliability/availability values for the SSF have been on the order of 95%. In fact, the PRA supports numbers as low as 90% with CDF numbers still < 1E-05. However, a program to control SSF reliability/availability will be implemented that meets the applicable requirements of NUMARC 87-00 Appendix B. The target will be to maintain reliability/availability > 95%.
The largest single contributor to SSF unavailability is dewatering of the Unit 2 CCW intake piping. This occurs infrequently and was not closely controlled in the past. Additionally, providing an alternate source of water is not cost effective for the marginal increase in availability that it would provide.
In order to reduce the vulnerability to an SBO event, planned maintenance on the SSF and Keowee will not occur at the same time.
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B. Coping from the Control Room:
- 3) Class I E Battery Capacity:
The licensee should develop and implement the necessary modifications, such as battery charging from an AAC power source or additional battery capacity, which will maint the main control rooms functional and manned for the full 4-hour SBO duration.
- 4) Effects of Loss of Ventilation The licensee should perform and provide for NRC staff review heat-up calculations for the areas containing SBO equipment associated with instrumentation and control functions (i.e., for control rooms, switchgear room, inverter room., etc.). If reasonable assurance of equlipment operability in these areas cannot be assured, the licensee should implement modifications and procedures to assure that the main control rooms are habitable, and that instrumentation and control equipment remains operable during an SBO event and recovery therefrom.
14
DUKE RESPONSE Command and control will be maintained in the Control Room for the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping duration time by stripping non-safety loads within 30 minutes. Procedures will be revised to perform the load stripping during an SBO event.
Results of heat up calculations for the Control Rooms show that habitability is assured without supplemental ventilation.
Calculations for the equipment rooms, battery rooms, and cable rooms indicate that temperatures remain below required equipment qualification temperatures. (Note NUMARC 87-00 Guidelines, Section 7.2.4, Appendices F & H).
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C. On-Site Emergency AC Reliability Program
- 5) EDG Reliability Program (Hydro Units)
It is the staff's position that reliability program for onsite energency ac systems (hydro units) should be developed in accordance with the guidance of RG 1.155, Section 1.2. If the reliability program currently exists, the program should be evaluated and adjusted in accordance with RG 1.155. Confirmation that such a program is in place or will be implemented should be included in the documentation that is to be maintained by the licensee in support of the SBO submittals.
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DUKE RESPONSE A program is being implemented which addresses the reliability and availability of the Keowee units that meets the applicable requirements of Appendix D of NUMARC 87-00. (Reg Guide 1.155, Table 1, indicates that Appendix D is an acceptable alternative to Section 1.2 of the Guide) 17