ML20034F230
| ML20034F230 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 02/26/1993 |
| From: | Woodard J SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9303020437 | |
| Download: ML20034F230 (3) | |
Text
i Southern Nuclear Opemting Company Post Offce Box 1295 brmingham Alabama 35201 Teiephone 205 BT;8 5066 L
Southern Nudear Operating Company f o. moey, Vee President the southern electre System Fadey Project l
February 26, 1993 Docket Nos:
50-348 50-364 U. S. Nuclear Regulatory Commission Attn:
Document Control Washington, D. C. 20555 Joseph M. Farley Nuclear Plant - Units 1 and 2 Unresolved Item 348, 364/92-17-07 Auxiliary Buildir.a Battery Voltaae Gentlemen:
The NRC Inspection Report Numbers 50-348/92-17 and 50-364/92-17 included Unresolved Item 348, 364/92-17-07, " Auxiliary Building Battery Voltage is Marginal for Present load Requirements."
A significant cuntributor to the NRC concern was described as follows:
"The TS and FSAR imply two hours of adequate battery voltage in the absence of other DC sources. The licensee's calculations demonstrated only a one minute capability. Licensee personnel stated that this was sufficient in that, within one minute of a loss of offsite power, EDGs would be in operation providing DC power through the chargers."
In response to this NRC concern SNC stated:
"It should be noted that although the batteries are only required to supply accident loads for one mi +.e without charger support, they are actually capable of supplying adequate voltage to all accident loads l
for approximately one hour based on preliminary calculations performed during the EDSFI."
The preliminary calculations mentioned above have been formalized.
The results of the calculations indicate that should the battery chargers fail to operate or sequence onto the emergency diesel generators subsequent to their start in response to an accident, the Unit 1 batteries are capable of supplying required accident loads for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and the Unit 2 batteries are capable of supplying required accident loads for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
The calculation documents that considerable time is available to manually load a battery charger should the load sequencer fail or to realign the swing battery charger should a charger fail.
It should be noted that since the Class IE chargers are automatically loaded onto the diesel generators in response to an accident, one emergency train will be available during the time the operator is restoring charger support to the opposite train.
n o n., 4 o 9303020437 930226 PDR ADOCK 05000348 PDR g
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j U. S. Nuclear Regulatory Commission Page 2 1
1 The decline in battery voltage in response to the loading described above is gradual such that raost loads would continue to receive adequate voltage well past the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> period mentioned for Unit 1 and the I hour period mentioned for Unit 2.
In fact, calculations demonstrate that all required Unit 2 loads would receive adequate voltage for the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> period with the exception of 2 l
breakers.
Manual action could be taken to exercise these breakers in response to an accident if necessary.
l In order to establish additional margin in the Unit 2 battery capability, SNC plans to modify the two breaker circuits that have been identified as the most limiting with regard to voltage drop.
This modification is presently scheduled for the Unit 2 Fall 1993 refueling outage.
Implementation of this modification will extend the time that the Unit 2 batteries can provide i
4 adequate voltage under the aforementioned scenario to at least 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
If there are any questions, please advise.
Sincerely, l
SOUTHERN NUCLEAR OPERATING COMPANY hd n
M j
l_
J. p. Woodard s
DPH:maf NRCABBAT.DPH NEL-93-0085 cc:
Mr. S. D. Ebneter Mr. S. T. Hoffman Mr. Francis Jape Mr. G. F. Maxwell i
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bc: Mr. R. P. Mcdonald -
Mr. W. G. Hairston, III Mr. R. D. Hill Mr. K. W. McCracken i
Mr. C. L. Buck, Jr.
Mr. J. W. McGowan 1
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