ML20006A719
| ML20006A719 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 01/19/1990 |
| From: | Bradham O SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Hayes J NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9001300093 | |
| Download: ML20006A719 (2) | |
Text
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r th Ca olina D3ctric & 0:s Comp:ny Otile S.
radhim Jenkinsvule. Sc 290$5' Nuclear Operations p*
(803) MS4040 J
S40Ei&CL suaan :nn January 19, 1990 4
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Document Control Desk 3
U.: S.' Nuclear Regulatory Commission Washington, D. C.-20555 Attention: Mr. John J. Hayes, Jr.
L
Subject:
Virgil C. Summer Nuclear Station L
Docket-No. 50/395 Operating License No. NPF-12 Update of Long Term Corrective 3
Action for July 11, 1989, Loss of Offsite Power Gentlemen:
1
-In the November 9, 1989, letter from Mr. O. S. Bredham to the NRC Document ControlDesk,itwasstated(answertoquestion#1)thatvoltageregulators for both the 230/7.2 KV Emergency Auxiliary Transformer and the 115/7.2 KV P
Engineered Safety Features Transformer were to be installed. After further
[
review and analysis it has been determined that the installation of a voltage l
regulator on the 230/7.2 KV Emergency Auxiliary Transformer is neither required:nor is there any. appreciable benefit derived from the installation of the voltage l regulator on the 230/7.2 KV line.
t The 230KV1 system design requirement is that it be able to withstand the loss
- of the largest plant or load on the 115 KV system and not result in the loss of the 2301G/ system. The 230 KV system is capable of doing this without voltage regulators with the existing voltage limits.
t Also, installing the voltage regulators on the 230 KV system would not
-provide enough advantage to be economically justified. This is based on the fact that the 230 KV system is tied directly to the Main Generator during-normal operation. This ensures that the voltage will be at or near 100% of a
nominal._ Since there is a minimum 10 second delay in the ability of the voltage regulators to adjust, it would not react fast enough to regulate voltage during a~ plant trip.
9001300093.900119 PDR ADOCK 05000395 S
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' Document Contro1' Desk January 19, 1990 IPage 2 of 2 Also, in.the November 9.-1989, letter it was stated (answer to question # 2) that the load flow study indicated that the resultant voltages for buses XSW-1DA and XSW-10B would be 93.85% of nominal and 94.95% of nominal respectively. After discovering that an input error to the load flow study was made it has been determined that the resultant voltage for buses XSW-10A and XSW-10B would be 94.05% of nominal and 96.05% of nominal respectively, i
Very truly yours, O. S. Bradham WRH/0SB:1bs c:
D. A. Nauman/0. W. Dixon, Jr./T. C. Nichols, Jr.
E. C. Roberts R. V. Tanner S. D. Ebneter J. J. Hayes, Jr.
General Managers C. A. Price R. B. Clary K. E. Nodland J. C. Snelson R. L. Prevatte J. B. Knotts, Jr.
File (818.05) l' 1.
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