ML20008E787
| ML20008E787 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/27/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NCR-SQN-EEB-803, NUDOCS 8103090653 | |
| Download: ML20008E787 (2) | |
Text
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.T' 400 Chestnut Street Tcwer II February 27, 1981
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Mr. Jame P. O'Reilly, Director y.
Office of spection and Enforcement M/}R0 6 IOOlh Q 1-2 U.S. Nuclea egulatory Comission (6
2 o g k "* outer n Region II - S e 3100 101 Marietta St t
g, Atlanta, Georgia (303 e,
D ' / 16 *, #
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - CFFSITE POWER VOLTAGE PLUCTUATION -
HCR SQN EEB 8034 - SECOND INTERIM REPORT The subject deficiency was initially reported to NRC-OIE Inspector R. W. Wright on October 20, 1980, in accordance with 10 CFR 50.55(e).
An interim report was submitted on November 19, 1980. Enclosed is our i
second interim report. We expect to submit our next report by April 3, 1981.
I If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
l Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Mana p r Nuclear Regulation and Safety Enclosure cc:
Mr. Victor Stello, Director (Enclosure Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 i
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3y 6103090653
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ENCLOSURE l
SEQUOYAH NUCLEAR PLANT UNIT 2 0FFSITE POWER VOLTAGE FLUCTUATION NCR SCN EEB 8034 i
l 10 CFR 50.55(e) l SECOND INTERIM REPORT 1
j Description of Deficiency During a degraded voltage study, it was discovered that the i
161-kV voltage minimum limit imposed on the operation of the 161-kV grid is not correct. This is because the 161-kV limit does not ensure adequate starting voltage for all safety-related 460-volt motors.
l This discrepancy is based en the present configuration of unit 1 in
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j full power operation and unit 2 in preoperational testing.
l j
Interim Progress I
TVA has calculated setpoints for future degraded voltage relaying in 1
order to assure adequate starting voltage for all safety-related l
j 460-volt motors (85 percent of rated voltage at the motor terminals).
The current 1cading configuration dictates that voltage at SQN must be I
no lower than 164 kV.
The 161-kV grid at Sequoyah is now operating with a j
i minimum voltage of 164 kV.
This limit is for unit 1 only in operation with unit 2 in preoperational status. TVA is in the process of determining what.
l correc:ive action will be necessary to support full operation of. unit 1 and j
unit 2.
a i
The TVA assumption of 85 percent minimum starting voltage is not yet corroborated by the vendor. NEMA MG-1-20.45, 1969, requires induction i
motors to be operated within + 10 percent of their rated voltage. TVA has
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received documentation from several of the vendors supplying 460-volt motors to TVA which verifies the 85-percent voltage starting capability.
L TVA is still awaiting the input of the several remaining vendors.
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