ML20056C068
| ML20056C068 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/24/1993 |
| From: | Fenech R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M0042B3, TAC-M42B3, NUDOCS 9303260156 | |
| Download: ML20056C068 (2) | |
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,t seuva%ew es March 24, 1993 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-327 Tennessee Valley Authority
)
50-328 SEQUOYAH NUCLEAR PLANT (SQN) - EXTENSION OF COMMIIMENTS ASSOCIATED WITH FAULT CURRENT PROBLEM FOR THE 6.9-KILOV0LT (kV) UNIT BOARD LOAD BREAKERS (TAC No. 00420B3)
Reference:
TVA letter to NRC dated November 29, 1991, "Sequoyah Nuclear Plant (SQN) - Fault Current Problem For The 6.9-Kilovolt (kV)
Unit Board Load Breakers (TAC NO.fp0420B3)"
This letter provides the current schedule for resolving the fault current problem associated with the 6.9-kV unit board load breakers for SQN.
In the referenced letter, TVA committed to complete this resolution by the end of the Unit 1 Cycle 6 refueling outage by providing normal alignment of unit power through the common station service transformers (CSSTs).
In addition, transfer circuits that align unit power to the spare CSST on transformer faults are to be modified to provide a fast transfer and minimize the impact to the operating units before the Unit 1 Cycle 6 refueling cutage.
The commitment to align unit power through the CSSTs will require an extension to the end of the Unit 2 Cycle 6 refueling outage presently scheduled to begin in September 1993. This extension is necessary because of required modifications to the load cables from the "C" CSST that were not known at the time this commitment was made. Evaluations of maximum normal station loads for the CSST showed that the load cables from the "C" CSST to the start boards would experience significant overheating under this load and need to be replaced. The procurement of these cables is in process but delivery will not support completion of corrective actions before the end of the Unit 1 Cycle 6 refueling outage. TVA will complete the modifications to increase the cable i
ampacity to support normal alignment of unit power through the CSSTs by the end of the Unit 2 Cycle 6 refueling outage.
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9303260156 930324 PDR. ADOCK 05000327 p
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e-e U.S. Nuclear Regulatory Commission Page 2 March 24, 1993 The commitment to provide a fast automatic trcnsfer to the spare CSST for transformer f aults will require an extension to the end of the L* nit 1 Cycle 6 refueling outage. This extension is required because of the impact of activities associated with the present two-unit forced outage and the revised start date for the Unit i refueling outage that has been moved up approximately three weeks.
This extension will not affect the resolution of the unit board fault current problem because this transfer f eature is only necessary once normal alignment through the CSSTs has been established, which is now planned during the Unit 2 Cycle 6 refueling outage.
Please dircct questions concerning this issue to K. C. Weller at (615) 843-7527.
Sincerely, 24Jd/w Robert A. Fenech cc:
Mr. D. E. LaBarge, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 NRC Fesident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-0199 i