ML19330B194
| ML19330B194 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/15/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-79-27, NUDOCS 8007310056 | |
| Download: ML19330B194 (3) | |
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TENNESSEE VALLEY AUTHORITY
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'l E'] J ul_18 A 8 :ad S 15, 1980 Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 1 - BULLETIN IEB 79 LOSS OF NON-CLASS IE INSTRUMENTATION AND CONTROL POWER SYSTEM BUS DURING OPERATION Enclosed is TVA's response to IEB 79-27 dated November 30, 1979, for the Sequoyah Nuclear Plant unit 1.
TVA's review of this matter has found no deficiencies as a result of this review.
If you have any questions concerning this matter, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY l
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. M. Mills, nager Nuclear Regulation and Safety Enclosure
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Mr. Victor Stello, Jr., Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 An Equal Opportunity Employer (s007310 0%
2 ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 1 RESPONSE TO BULLETIN IEB 79-27 LOSS OF NON-CLASS IE INSTRUMENTATION AND CONTROL' POWER SYSTEM BUS DURING OPERATION Item la: We have identified all class lE and nonclass lE buses which supply power to safety-and nonsafety-related instrumentation and control systems that are required to achieve cold shutdown <
As a result of this review, we believe that, for each bus identified, the system design is more than adequate to ensure that at least one source of power is available to each bus at all times.
As a part of this review, we examined in detail the alarm, and/or indication provided in the control room which alerts the operator of the loss of power to the bus. No deficiencies were discovered as a result of this review.
Item lb: We have performed an analysis of each bus identified in item la and have evaluated the effects of a sustained loss of power to the instrument and co,ntrol system loads supplied by each bus required to achieve cold shutdown. No deficiencies were discovered as a result of this evaluation.
Item ic: At the present time, no design modifications are being propose' as a result of the reviews and analysis undertaken for items it and lb.
We are continuing our review of the results of the anal.>is.
Should deficiencies or design-related defects be di,s; vr'ed as a result of the review process, the appropriate desia sodific-will be scheduled and implemented.
I i
Items 2a, 2b, 2c:
As of July 9, 1980, the appropriate emergency procedures have been prepared to include the information requested in i
items 2a, 2b, and 2c.
These emergency procedures are present$
being reviewed by the Plant Operations Review Committee and will be approved and issued for use before the. issuance of th$
full power operating license. There are no design changes or administrative controls to be implemented is a result of the preparation and review of these emergency procedures.
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W2 have review:d IE Circular 79-02, "Failura of 120-V Vital AC Power Supplies," dated January 11, l.979.
As a result of 1
this review, we have determined that there are no deliberate time-delay circuits utilized in the vital and preferred 120-V ac power supplies for unit 1 at Sequoyah. The inherent response times of the circuits are adequate and acceptable, and proper undervoltage settings have been verified. No modifications to the design or administrative controls are required as a result of IE Circular 79-02.
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