ML19312D226
| ML19312D226 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/17/1980 |
| From: | Conway W VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Gammill W Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19312D227 | List: |
| References | |
| WVY-80-44, NUDOCS 8003210570 | |
| Download: ML19312D226 (2) | |
Text
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VERMONT YAN KEE NUCLEAR POWER CORPORATION SEVENTY SEVEN GROVE STREET B.3.2.1 RUTLAND, VEMMONT ' 05701 WVY 80-44
,espLv von ENGINEERING OFFICE i'
TURNPIKE RC Ao WESTBORO. M ASS ACHUSETT $ 0 t S61 March 17, 1980 75'a m+"**"'
' United States Nuclear Regulatory Commission Washington, DC 20555 Attention: ' Division of. Operating Reactors Mr. William Cammil, Acting-Assiste.st Director For Operating Reactor Projects
References:
(1 ) License No. DPR-28 (Docket No. 50-271 )
(2) USNRC Letter to All Power Reactors dated August 8,1979 (3) VYNPC Letter to tJSNRC, LER 80-11/IP, dated March 13, 1980
Dear Sir:
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Subject:
Adequacy of Station Electric Distribution System Voltages As-required in Reference (2), we have reviewed the electric power systems at Vermont Yankee to determine if the 'of fsite power system and onsite electric distribution system is of sufficient capacity and' capability to automatically start and operate all safety loads if all onsite power sources are not avail abl e..
In developing this' response we have been made' aware of two potential i
' concerns.
One' concern relates to a potential high' vol tage that could exist 'on the 4160 vol t system when' the _ plant is of f-line and grid vol tage is at the-maximum expected value. The other concern relates to a potential low vol tage I'
that could exist on the 480 volt system if the plant was in the closed cooling cycle mode,- and the grid voltage was at the minimum expected value and an accidentL occurs.' - The. potential concerns were reported in Reference (3).
IBy changing transformer taps on startup transformers T-3A and T-3B and on 4160/480 volt transformers the potential concerns can be corrected.
Transformer tap changes 'will. be made. before Vermont Yankee begins closed cycle cooling l operation.- Because Vermont Yankee is presently operating in the open
- cycle cooling mode no. problem exists at this time.
Our. analysis which was based on the guidelines 'of: Enclosure 2 of
...-Reference (2) demonstrates that, subject to the-tap change described above, lthe auxiliary power system is adequate to start and operate all.. safety loads.
J The' analysis -is. contained L in the attached report,n YAEC #1205, "Auxil iary Po'wer System Vol tage Studyxfor Vermont Yankee Nuclear Power. Station."
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lU.S. Nuc1ccr Regulctcry Commicsien-Pcga.2 4
- Attcsticn Mr. Willica G mmil M:rch 17,1980 ll; '
Reference (2) also. required that 'the adequacy of the onsite and of fsite power distribution systems be verified by test to assure that the analysis
. resul ts are valid.. Because-of the impracticality of simulating high and low L vol tage conditions in the transmission system together with various conditions in the1 plant' we have chosen to verify' the analysis using our computer program and our model cf the station auxiliary power -system to predict bus voltages for actual plant conditions.
The verification is al so contained in the attached report. ' Comparison of bus voltages predicted hf the computer program to actual. bus _ vol tages demonstrates that the computer model is valid.
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We have also reviewed the electric power systems at Vermont Yankee and found total. compliance with GDC-17.
We'have determined that, to the extent practical, there are no events or conditions which could resul t in the simul taneous or. consequential loss of both' required circuits to the of fsite network.
We trust that this information is satisfactory; however, should you desire additional information, ' please contact us.
Very truly yours.
VERMONT YANKEE NUCLEAR POWER CORPORATION N/A a
W. F. Conway Ma'ager of Operations n
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