ML20012A076

Forwards Rept Re 6.9-kV Diesel Generators Installed at Plant.No Recorded Failures Noted in Approx 55 Starts Per Diesel Generator.Number of Diesel Generator Starts Reduced from Approx 170 to 55 Starts Per Yr

ML20012A076
Person / Time
Site:	Sequoyah
Issue date:	03/01/1990
From:	Wallace E TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9003080253
Download: ML20012A076 (2)

Text

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, , '. ; ~ ' ~ % TENNESSEE VALLEY- AUTHORITY -

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SN 157B' Lookout Place IS March 1.:1990

- U.S. Nuclear Regulatory Comission

-ATTN: Document Control-Desk-Washington, D.C.- 20555 Gentlemen:

In the Matter _of- ) Docket Nos. 50-327-l Tennessee Valley Authority )- 50-328 SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 - DIESEL GENERATOR RELIABILITY DATA REPORT The enclosed report provides details concerning the 6.9-kilovolt diesel generators installed at:SQN. This report is being submitted in accordance

.with Technical Specification 6.9.2.2.

Please-direct questions concerning this issue to Bruce S. Schofield at (615)~843-6172.

Very truly yours, TENNESSEE VALLEY AUTHORITY u

E. G. Wallace, Manager Nuclear Licensing and Regulatory' Affairs 4

Enclosure cc:~ Ms. S. C. Black, Assistant Director (Enclosure) for Projects TVA Projects Division U,E. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville. Maryland 20852 Mr. B. A. Wilson, Assistant Director (Enclosure)

'for Inspection Programs

,' TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector (Enclosure)

Sequoyah Nuclear Plant

2600 Igou Ferry Road ,

Soddy Daisy, Tennessee 37379 O t 27 An Equal Opportunity Employer /

P PNU

, . . . . j ENCLOSURE' SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 l DIESEL GENERATOR RELIABILITY DATA REPORT l This report is submitted pursuant to Technical Specification '6.9.2.2 to satisfy the requirement for a yearly data report on diesel generator (DG) reliability. The 6.9-kilovolt (kV) DGs at Sequoyah Nuclear Plant serve as the onsite Class 1E power source. Surveillance requirements.of technical specifications that demonstrate DG operability are accomplished by the routine performance of Surveillance Instruction (SI) 7. " Electrical Power System:

Diesel Generators Unit 0, 1, and 2," SI-7.1, " Diesel Generator AC Electrical Power Source Operability Verification (Diesel Generator /Offsite Source) -

Unita 1 and 2," the SI-26 series for loss of offsite power coincident with a safety injection, and the SI-102 series for the inspection of DGs. Listed below is a tabulation of DG testing data recorded during the performance of the aforementioned sis as well as data recorded during the performance of special test instructions and special maintenance instructions. The data was taken from testing performed during the period between January 1, 1989, and December 31, 1989. " Valid tests" and " invalid tests" are defined in accordance with the criteria established in Regulatory Guide 1.108, Revision 1. August 1977.

Diesel Generator Valid Tests Invalid Tests Failures lA-A 15 43 0 1B-B 13 42 0 2A-A 15 45 0 2B-B 17 36 0 The above data of approximately 55 starts per DG with no recorded failures supports the conclusion that the reliable performance of the 6.9-kV DGs at Sequoyah provides a high confidence level the DGs will perform if required.

L TVA recognizes the importance of reducing the number of DG starts and has

. received a requested change to technical specifications. Before the change, technieni specifications required, in part, that the remaining DGs be demonstrated operable within one hour and every eight hours when a DG became inoperable. The recent change requires, in part, that the remaining DGs be demonstrated operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a DG becomes inoperable. Based on this change, the number of starts per DG has been reduced from approximately 170 per year to approximately 55 per year. This change has greatly reduced the number of required starts of each 6.9-kV DC, thereby increasing engine

' life without compromising reliability, i

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