ML20244E253
| ML20244E253 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/12/1989 |
| From: | Hairston W GEORGIA POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20244E254 | List: |
| References | |
| RTR-REGGD-01.155, RTR-REGGD-1.155 HL-396, NUDOCS 8904240377 | |
| Download: ML20244E253 (6) | |
Text
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X7GJ17-H220 April 12, 1989 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C.
20555 PLANT HATCH - UNITS 1, 2 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57 NPF-5 RESPONSE TO STATION BLACK 0UT RULE Gentlemen:
As required by 10CFR 50.63(c)(1), Georgia Power Company (GPC) hereby submits as an enclosure to this letter an executive summary and report which discusses the capability of Plant Hatch to cope with a Station Blackout (SBO).
The evaluation was performed in accordance with the guidance provided in Regulatory Guide 1.155, " Station Blackout," and NUMARC 87-00,
" Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Hater Reactors."
This report demonstrates compliance with 10CFR 50.63 by impleicentation of procedural changes with no substantial hardware modifications.
The report justifies a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />' coping duration with use of the emergency diesel generator 18 as the alternate AC power source (AAC).
A combination of battery power and emergency AC power from the AAC source can be used to bring the blacked out unit to and maintain a hot shutdown condition from full power.
Adequate core cooling capability and equipment necessary to cope with an SB0 will be available to both the blacked out unit and the non-blacked out unit.
Manual operator actions required to satisfy the SB0 requirements will be proceduralized and implemented at Hatch Units 1 and 2.
As required by Reg. Guide 1.155, detailed information which supports the enclosed report will be available for your review.
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U.S. Nuclear Regulatory Commission April 12, 1989 Page Twa The procedure changes and an FSAR update will be implemented no later than two years following the notification of report approval provided by the Director, Office of Nuclear Reactor Regulation in accordance with 10 CFR 50.63(c)(3).
Should you have any questions in this regard, please contact this office at anytime.
l Sincerely, ut.L Li%
H. G. Hairston, III SJB/eb
Enclosure:
E. I. Hatch Units 1 and 2 Station Blackout Report c: Georgia Power Company Mr. H. C. Nix, General Manager - Hatch Mr. L. T. Gucwa, Manager Engineering and Licensing - Hatch GO-NORMS Lt.S. Nuclear Regulatory Commission. Washinaton. D.C.
Mr. L. P. Crocker, Licensing Project Manager - Hatch U.S. Nuclear Reaulatory Commission. Reaion II Mr. S. D. Ebneter,. Regional Administrator Mr. J. E. Menning, Senior Resident Inspector - Hatch 0057V
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ENCLOSURE PLANT HATCH - UNITS 1, 2 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES OPR-57, NPF-5 STATION BLACK 0UT REPORT l
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E. I. HATCH UNITS 1 AND 2 STATION BLACK 0UT REPORT EXECUTIVE
SUMMARY
APRIL 1989 I
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l The term " station blackout" (SBO) is defined to mean the loss of offsite AC power to the essential and non-essential electrical busses concurrently with turbine trip and the una"ailability of the redundant onsite emergency AC power systems.
The NRC issued the Station Blackout Rule,10 CFR 50.63, on June 21, 1988.
The objective of the rule is to reduce the risk of severe accidents resulting from station blackout by maintaining highly reliable AC electric power systems and, as an additional defense-in-depth, assure that nuclear power plants can cope with a station blackout for a specific period of time.
4 The " Station Blackout Rule", 10 CFR 50.63, is the governing criteria for this report.
Regulatory Guide 1.155 describes methods acceptable to the NRC staff for compliance to the SB0 Rule.
The Nuclear Management and Resource Council (NUMARC) document NUMARC 87-00 provides additional industry guidance I
for conformance to 10 CFR 50.63.
Regulatory guidance specifies that either unit must successfully cope with the blackout condition for a predetermined amount of time based on site-specific characteristics.
The specific station blackout duration is based on the redundancy of the onsite emergency AC power sources; the I
reliability of the onsite emergency AC power sources; the expected frequency of loss of offsite power; and the probable time needed to restore offsite power.
The reactor core cooling and associated systems provide sufficient capacity and capability to ensure that the core is cooled and appropriate containment integrity is maintained in the event of a station t,lackout for the determined duration. Through use of the NUMARC 87-00 document, a coping duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> has been assessed for Hatch Units 1 or 2.
The 4-hour coping duration is based on offsite power design characteristic group P1, emergency AC power configuration group C, and an allowed emergency diesel generator target reliability of 0.95.
Emergency diesel generator (EDG) 1B is designated as the alternate AC power source since it is not required for a station LOSP.
Only one out of two EDG's from each unit is required to achieve and maintain the unit in a hot shutdown condition, under normal circumstances.
The qualification process for using EDG 18 as the AAC source is itemized within the body of the Station Blackout Report.
During a blackout of either unit, the AAC power source will be available to support equipment loads necessary to achieve and maintain the blacked out unit in a hot shutdown condition.
0619I HL-396 i
The coping duration is considered to be 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, however, the Alternate AC (AAC) source will be available within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of the loss of offsite power (LOSP) event.
The 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> duration was determined based on an indepth review of the limited number of operator manual actions required to utilize the AAC source and the fact that the AAC will be available for loading within 12 seconds of an LOSP. Plant operation is controlled by predominantly DC power and steam driven sources until the AAC source is available for loading within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
Station blackout is not a design basis accident and, therefore, is not subject to the requirements of 10 CFR 50.49 and the rigorous certification process for equipment operability.
However, since SB0 coping equipment needs to operate in order to achieve and maintain a safe shutdown, reasonable assurance is provided to demonstrate that no thermally induced failures will result due to loss of forced ventilation.
In addition to equipment operability, appropriate containment integrity and adequate 1
condensate inventory is demonstrated within the Station Blackout Report.
Manual operator actions required to satisfy the station blackout requirements will be proceduralized and implemented at Hatch Units 1 and 2.
Procedures and training will include all operator actions necessary to cope with a station blackout for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and to restore normal, long-term core cooling and decay heat removal once AC power is restored.
The report conclusively shows 'that both units at Hatch can successfully cope with a station blackout for a 4-hour coping duration by using EDG 1B as the AAC power source.
0619I HL-396 ii