ML18130A526
| ML18130A526 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 09/04/1979 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| 583, NUDOCS 7909060155 | |
| Download: ML18130A526 (1) | |
Text
e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND,VX:RGINIA 23261 September 4, 1979 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation Attn:
Mr. A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Serial No. 5 83 PO/FHT:baw Docket Nos.
50-280 50-281 DPR-32 DPR-37 License Nos.
Subject:
Surry Power Station Units 1 and 2 Degraded Grid Voltage
Dear Mr. Denton:
We have reviewed your letter of July 11, 1979, requesting additional infor-mation on degraded grid voltage at Surry Power Station by August 31, 1979.
We have determined that a design change should be implemented to assure a reliable power source to the emergency buses for all safety loads in the event of sustained undervoltage on the grid.
The present design starts the emergency diesel generators (EDG's) if the emergency bus voltage drops to 84% of nominal, and loads the EDG's when bus voltage reaches 79.5%.
The proposed design change will prevent a sustained undervoltage condition on the station emergency buses by starting and loading the EDG's if the voltage falls below 90% for more than 1 minute.
This will provide assurance that all safety loads will be started and operated normally in the event they are needed.
Since the design has not yet been finalized, a proposed change to the Surry Technical Specifications has not been generated. We expect the design change to be completed by late September and we will forward the design change and Technical Specification change on or about October 15, 1979.
cc:
1'909 060 155 Very truly yours, H~-~
C. M. Stallings
~
Vice President-Power Supply and Production Operations