ML20078G985
| ML20078G985 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, 05000378  |
| Issue date: | 11/04/1994 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9411160289 | |
| Download: ML20078G985 (3) | |
Text
_ _ - _
Station Support Dspartmsnt A
v PECO ENERGY.
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96S Chesterbrook Boulevard Wayne, PA 19087-5691 i
November 4,1994 Docket Nos. 50-277 50-278 License Nos. DPR-44 DPR-56 i
U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 I
Subject:
Peach Bcn m Atomic Power Station, Units 2 and 3 Completion of the Conowingo Tie Line, and Compliance with 10 CFR 50.63, Loss of All Alternating Current l
Reference:
1)
Letter from D. M. Smith to USNRC Document Control Desk, dated August 6,1992 2)
Supplemental Safety Evaluation Report (SSER), Peach Bottom Atomic Power Station, Units 2 and 3, dated October 23,1992, received by PECO Energy November 4,1992 3)
Response to a Request for Additional Information (RAl),
G. A. Hunger, Jr. to USNRC Document Control Desk, dated September 6,1994
Dear Sir:
This lettu is being submitted to inform you that PECO Energy Company (PECO Energy) has completed the physical and programmatic changes necessary to be in compliance with 10 CFR 50.63, Loss of All Alternating Current, commonly Galled Station Blackout (SBO) at Peach Bottom Atomic Power Station, Units 2 and 3. In addition, some clarifications to the testing procedures and the operability requirements for the Conowingo Tie Une are being provided by this letter.
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Nov:n a ~ 4,1994 Pag 3 2 In Reference (1), PECO Energy provided a response to NRC Questions concerning the use of the Conowingo Hydroelectric Power Station as an Alternate AC power source for PBAPS. The NRC, based on the details provided in Reference 1, issued their Supplemental Safety Evaluation Report (SSER, Reference 2). This SSER accepted that the proposed design would
)
bring PBAPS into compliance with the SBO rule, and when received by PECO Energy, initiated a two year clock for implementation of the SBO rule, in accordance with 10 CFR 50.63 (c)(4).
In Reference (1), PECO Energy provided a description of the necessary equipment at Conowingo Hydroelectric Station. In this description, PECO Energy stated that a combination of one small generating unit (36MW) at Conowingo and one large generating unit (65MW) at Conowingo would be needed to provide transient stability during the start of large loads at PBAPS.
During the design analysis of this modification, it was calculated that any one of six units of the 11 total units at Conowingo could provide a stable source of power for PBAPS. These six units include tour of the 36MW and two of the 65MW units.
Also in Reference (1), PECO Energy provided a discussion of the pre-operational testing to be performed prior to placing the Conowingo Tie Line in service. The pre-operational testing was completed and accepted; however, rather then placing 7000 KW of load on the line, approximately 6000 KW was placed on the line. A computer model of the Conowingo Tie une was run based on the loads and expected parameters, and the model verified that the line could adequately carry the SBO loads. The computer model allowed PBAPS to verify the adequacy of the Conowingo Tie Une, without realigning several emergency buses, and adversely impacting operations at PBAPS.
These bus alignments would have been necessary to mimic the loads expected during an SBO.
In Reference (3), PECO Energy informed the NRC that as a planned compensatory measure when the Conowingo Tie Une was out of service, Gsnarcl Procedure (GP) 23, " Diesel Generator Ottages" would be revised to perform an off-site power breaker alignment and voltage check within one hour of declaring the Conowingo Tie Une inoperable, and that this breaker alignment and voltage check would be performed once per every eight hours thereafter.
It is now recognized that it is more appropriate for this breaker alignment and voltage check to performed as part of the newly written Conowingo Tie Une out of service procedure, and that while the breaker alignment and voltage check will be performed within one hour, the appropriate frequency of performance is once per day. This frequency is adequate because of the high reliability of the Emergency Diesel Generators, and the inherent stability of the off-site power supply grid.
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a November 4,1994 i
Pag 3 3 if you have any questions, please contact us.
Very truly yours, k.
1 h.
G. A. Hunger.
Director - Ucensing cc:
T. T. Martin, Administrator, Region I, USNRC W. L. Schmidt, USNRC Senior Resident Inspector, PBAPS l
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