ML20126E663

Special Rept 92-10:on 921110,thermal Detection Instrumentation in Reactor Coolant Pump Area Declared Inoperable When Trouble Alarms Received.Cause Unknown.Lower Containment Compartment Air Temp Monitored Once Per H

ML20126E663
Person / Time
Site:	Sequoyah
Issue date:	12/22/1992
From:	Fenech R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
92-10, NUDOCS 9212290257
Download: ML20126E663 (3)

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Hobert a fenoch vu.a hrvcent. Stepn eh rai+a, Piant December 22, 1992 U.S. Nucicar Regulatory Commission ATTN Document Control Desk Washington, D.C. 20555 Gentlement In the Matter of

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Docket No. 50-327 Tennessee Valley Authority

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SEQUOYAll NUCLEAR PLANT (SQN) - UNIT 1 - FACILITY OPERATING LICENSE DPR TECllNICAL SPECIFICATION (TS) 3.3.3.8 SPECIAL REPORT 92-10 The enclosed special report provides details concerning the inoperability of the fire detection instruments in Fire Zones 357 and 369. These zones are in the Unit-1 reactor building lower containment in the area of reactor coolant pump Nos. 2 and 4, respectively.

These fire detection instruments will be out of service until the next outage of sufficient duration to correct the problems and return the instrumentation to operable status.

The recurring failures of fire detection instrumentation in the Unit i lower containment in the reactor coolant pump areas is currently under evaluatloa to develop appropriate corrective actions. This report is being submitted in accordance with TS Action Statement (b) of Limiting Condition for Operation 3.3.3.8.

If you have any questions concerning this submittal, please telephone C.11. Whittemore at (615) 843-7210.

Sincerely, f[ MA Robort A. Fenech Enclosure cet See page 2 f

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t U.S. Nuclear Regulatory Connission Page 2-I December 22, 1992 f

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Mr. D. E. LaBarge, Project Manager 1

U.S. Nuclear Regulatory Connission une White F1h.t North 11555 Rockville Pito Rockville, Maryland 20852-2739 I

NRO hesidsnt Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Mr. B. A. Wilson, Project Chief U.S. Nacicar Regulatory Connission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Geor8 a 30323-0199 1

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i ENCLOSURE a

SEQUOYAll NUCLEAR PLANT (SQN)

SPECIAL REPORT 92-10 4 4 2k Deacrlittlon_of_Cnndi_ tion

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On November 10, 1992, with Unit 1 in Mode 1, the thermal fire detection inst rumentation in the Unit I reactor coolant pump (RCP) No. 2 area was gi((d declared inoperable, and Limiting Condition for_ Operation (LCO) 3.3.5.8 t3 was entered. T ouble alarms were acknowledged on Panel 0-PNL-13-631 for byA,hudQ^4 Fire Zone 357. Several attenpts to identify and resolve the problem and

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maintain the operability.. the fire detectors were nasuccessful.

The taermal detectors cannot be repaired until the next " age of adequate dr.ation. On November 16, 1992, the same condition,

eloped in Fire Zone 369 in the RCP No. 4 area.

Cause_of_ Condition The thermal detectors in the area of RCP Nos. 2 and 4 have repeated.,

brought in the troubla alarms on the pyrotronics system (Panels-631 and 629). ' These alarma e supervisory circuits that transmit low tacrent signals and r-

- the resistance in the electrical system to detarmine if the detector's integrity is good. The cause of the problem is unknown at this time because the instruments are located in the lower i

coitairunent compartmer t area, and troubleshooting cannot be performed 23 until nr outage of adequate duration.

Grrectire_.Actir i In accordance wit. LCO 3.3.3.8 Action Statement (a), the Unit i lower containment compartment air temperature is being monitored at least once every hour and will continue to be monitored until the detectors are restored to operable status. The detectors and system circuits wi.11 be inspected and evaluated as to the cause of the sporadic operation. Work requests have been written and placed on the forced-outage item list.

SQN will remain in LCO 3.3.3.8 until the detectors are repaired and/or replaced. An evaluation of the recurring failures of the RCP fire detector circuits is ongoing to develop appropriate corrective actions.

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