ML20112C980
| ML20112C980 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 05/29/1996 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9606030274 | |
| Download: ML20112C980 (4) | |
Text
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Southern Nuciar Optriting Company Post Offica Box 1295 Birmingham. Alabama 35201 Telephone (205) 868-5131 k
L Southem Nudear Operating Company o.ve morey l
Vice President Farley Project the southem electnc system -
May 29, 1996
]
Docket Nos.: 50-348 i
'50-364 j
U. S. Nuclear Regulatory Commission ATTN: Document ControlDesk 4
l Washington, DC 20555-0001 Joseph M. FarleyNuclear Plant Comments on Draft 1982-83 Precursor Report Ladies and Gentlemen:
Southern Nuclear Operating Company has reviewed the information in the draft Accident i
Sequence Precursor (ASP) report provided by NRC letter dated May 7,1996. Our comments j
are provided below.
B.45 LER No. 348/82-018 1)
The event description title (B.45.2), " Transient with one motor-driven AFW pump inoperable," is inaccurate. The event description should be: " Transient with motor-driven AFW flow path to 1 of 3 steam generators degraded."
2)
The analysis of the event seems to be based on the assumption that the flow control valves (FCVs) are normally closed and must open in response to an initiating event.
Under normal operating conditions, the FCVs are maintained fully open with the AFW pumps in the automatic start mode to ensure that the AFW System is ready to provide flow to the steam generators. The valves would be expected to be in the less than fully open position only under the following conditions:
During a test of the motor-driven pumps or turbine-driven pump the appropriate valves are closed to prevent feeding the steam generators; and During a plant startup or shutdown when AFW flow is regulated (i.e., throttled)
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to maintain steam generatorlevels.
Ah 9606030274 960529 030yg,z PDR ADOCK 05000348 P
i U. S. Nuclear Regulatory Commission Page 2 At the time of discovery, FCV-3227A was 75% open, and the plant was at approximately 18% power (60 MWs ) with main feedwater aligned to the steam generators. Also, per procedure, the motor-diven pumps discharge flow control valves FCV-3227A, B, and C and the turbine-driven pump discharge control valves FCV 3228A, B, and C were being placed in the fully open position after transferring from auxiliary feedwater to main feedwater.
3)
The modeling assumptions (B.45.4) incorrectly imply that the Train A flow path is separate from the Train B flow path. For the Farley design, both the Train A and Train B motor-driven AFW pumps provide flow via a cross-connection header to all steam I
generators through FCV-3227A, B, and C. Assuming common cause failure of the FCVs to open is overly conservative since these valves are normally open. Therefore, an additional failure of either FCV-3227B or C would not render either train ofmotor-driven AFWinoperable.
L Attached is a simplified figure of the AFW System for Farley Nuclear Plant for your reference.
Should you have any questions, please advise.
Respectfully submitted, f{ N'"f Dave Morey RAH / cit:precur. doc Attachment cc:
Mr. S. D. Ebneter, Region II Administrator Mr. B. L. Siegel, ~ NRR Senior Project Manager Mr. T. M. Ross, FNP Sr. Resident Inspector i
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