ML20093D852
| ML20093D852 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/21/1984 |
| From: | Sinclair J VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| FVY-84-69, NUDOCS 8407170253 | |
| Download: ML20093D852 (1) | |
Text
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VERMONT YANKEE NUCLEAR POWER CORPORATION RD 5, Box 169, Ferry Road, Brattleboro. V T 05301
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ENGINEERING OFFICE FVY 84-69 1671 WORCESTER ROAD FRAMINGHAM, MASSACHl>SETTS 01701 TELEPHONE 617-472-8100 nited States Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Office of Nuclear Reactor Regulation Mr. Domenic B. Vassallo, Chief Operating Reactors Branch No. 2 Division of Licensing
References:
(a) License No. DPR-28 (Docket No. 50-271)
(b) Letter, VYNPC to USNRC, FVY 84-46, dated May 15, 1984
Subject:
Degraded Grid Voltage Protection
Dear Sir:
By letter dated May 15, 1984 [ Reference (b)], we provided you with additional information regarding our proposed scheme for degraded grid voltage protection at our facility. Subsequent to our submittal, we have held conference calls with members of your staff to clarify certain details of this scheme. The purpose of this letter is to provide you with the following information which supersedes our response to Item (1) of Reference (b).
Loss of normal ac power, or low emergency bus voltage sensed on an emergency bus for ten seconds in conjunction with an accident signal, will cause the following sequence of events:
a.
The associated diesel generator will start, b.
The bus tie breaker between the emergency bus and the off-site power source will open, and c.
The emergency bus will shed loads.
j Once the diesel generators are at their required operating voltage, the diesel generator breakers close, and the emergency bus loads are sequenced onto the bus. While the diesel generators are supplying the emergency buses, load shedding is blocked by relay logic. The scheme includes an additional relay which automatically reinstates load shedding, should either diesel generator breaker trip.
We trust that the above information is deemed acceptable; however, should you have any questions regarding this matter, please contact us.
Very truly yours, 84j7Qg38 bl VERMONT YANKEE NUC, LEAR POWER CORPORATION PDR P
. B. Sinclair p
Licensing Engineer lg gI[
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