ML20044B219

Eagle 21 Start-Up Rept for 900522- 0616. W/900713 Ltr

ML20044B219
Person / Time
Site:	Sequoyah
Issue date:	07/13/1990
From:	Wallace E TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9007180148
Download: ML20044B219 (3)

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TENNE 2CEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 374o1 SN 157B Lookout Place L JVL 131990 L

U.S. Nuclear Regulatory Commission AITN Document control Desk

' Washington, D.C. 20555 Centlement l In the Matter of ) Docket No. 50-327 Tennessee Valley Authority )

SEQUOYAll NUCLEAR PLANT (SQN) - EAGLE 21 START-UP REPORT

Reference:

TVA letter to NRC dated May 10, 1990. "Sequoyah Nuclear Plant (SQN) - Eagle 21 Functional Upgrade Commitments" In the referenced letter. TVA committed to submit a report describing design hardware, design'softwarc, and maintenance problems with Eagle 21 encountered during Unit 1 start-up and power ascension f rom the Cycle 4 refueling outage.

The enclosed information is provided to satisfy this commitment. This report covers the period of May 22,1990 (Unit 1 Mode 4 entry). to June 16, 1990 (Unit I at 100 percent power).

if you have any questions cone',rning this issue, please contact Russell R. Thompson at (615) 843-7470.

t Very truly yours.

TENNESSEE VALLEY AUTil0RITY b.jO. Wallace. Manager Nuclear Licensing and Regulatory Affairs Enclosure cc: See page'2 l ph An Equal Opportunity E.mployer

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,, l' U.S. Nuclear Regulatory Commission 13 m i

L cc (Enclosure):

Ms.' S. C. Black, Deputy Director

[ Project Directorate 11-4 L U.S. Nuclear Regulatory Commission One White Flint, North 11555'Reckville Pike Rockville, Maryland 20852 Mr. J. N. Donohew U.S. Nuclear Regulatory Commission One White Flint, North

-11555 Rockville Pike Rockville, Maryland 20852 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia- 30323 s

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ENCLOSURE

, SQN Eagle 21 Start-Up Report For

, Period May 22-June 16, 1990 i

i On May 23,1990, during the performance of Surveillance Instruction (SI) 1-SI-IFT-68-002.1, " Functional Test of AT/Tavg Channel I Rack 2 Loop T-68-2 (T-411/412)," Rack 1-R-2 of the reactor protection system failed to enter the ,

surveillance mode. The protection portion of the rack remained functional and ,

2 operable during this failure. There was no effect on other plant equipment, r and no technical specification action provisions applied. ,

The fault was traced to an Eagle 21 resistance temperature detector input (ERI) board located in terminal frame 04. The ERI board was replaced, and the  ;

suspect board was returned to Westinghouse Electric Corporation for testing.

No problems were identified with the ERI board during the Westinghouse testing. Rack 1-R-2 continued to function normally until June 21, 1990, when the same failure occurred. After this failure, it was determined that the cause for both f ailures was a faulty surveillance injection and response (SIR) bus cable, which caused the ERI board to appear defective. The specific failure prevented surveillance. test signals from reaching the ERI board. The SIR bus cable was replaced, with the faulty cable being returned to '

Westinghouse for failure analysis.

There have been two instances of test sequence processor (TSP) " lock-ups"  ;

(Rack 1-R-3 on May 254 Rack 1-R-13 on June 13). The TSP lock-ups were identified by the receipt of a channel set failure alarm in.the main control room with no corresponding bistable trips for that channel. A TSP lock-up is characterized by status LEDs in the rack indicating that the TSP has stopped functioning. Although some normal online diagnostics are lost during a TSP lock-up, the loop calculation processor remains functional and operable. No other plant equipment was effected. The lock-ups were discussed with Westinghouse and, based on their reconsnendations, voltage measurements between the logic ground and the cabinet were taken, and the racks were reset. The TSP lock-up phenomenon is currently being evaluated by Westinghouse. The results of this evaluation will be provided to NRC in a future periodic t Eagle 21 performance report.

On May 31, 1990, interrupts of the P-250 plant computer were c = co by intermittent tripping of the output circuit for Temperature Switch TS-68-67-J in Rack 1-R-13. Main control room alarms were not received because the temperature switch output circuit was not in the trip state long enough to energize the annunciator system relays. After discussions with Westinghouse, a potentiometer was adjusted that affected the timing of the output circuit's

" dead-man" timer. The dead-man timer provides fail-safe operation by causing an output to trip after a brief time-out (approximately 120 milliseconds) if the loop processor subsystem fails. The dead-man timers in the other Eagle 21 output' circuits were checked, and no other incorrect settings were discovered. It was concluded that the potentiometer had not been properly set 4

by the manufacturer at the factory, and that the incorrect setting was an isolated case. The TS-68-67-J circuit has functioned properly since this adjustment.

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