ML20149E255

Special Rept 94-05:on 940407,Unit 2 Fire Detectors Declared Inoperable,On 940416,fire Protection Sprinkler Sys in ABGTS Filter Housing Area Declared Inoperable & on 940415,fire Protection Hose Station in ERCW Bldg Taken Out of Svc

ML20149E255
Person / Time
Site:	Sequoyah
Issue date:	05/23/1994
From:	Powers K TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
94-05, 94-5, NUDOCS 9405270189
Download: ML20149E255 (5)

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l Tenresam Valhy Adr.Wy, Peat Offi ce Dox 2000. Soddy-Dasy. Tenrerte 37379-2000 Ken Powers w:4 emon. semyan nucwar rww May 23, 1994 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Centlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAll NUCLEAR PLANT (SQN) - UNITS 1 AND 2 - FACILITY OPERATING LICENSES DPR-77 AND DPR TECHNICAL SPECIFICATIONS (TSs) 3.3.3.8, 3.7.11.2, AND 3.7.11.4 - SPECIAL REPORT 94-05 The enclosed special report provides details concerning fire suppression and fire detection systems being impaired for a period of time greater than the TS allowable timeframe.

This report is being submitted in accordance with TS 3.7.11.2 Action

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Statement (a), TS 3.7.11.4 Action Statement (a), and TS 3.3.3.8 Action Statement (b).

If you have any questions concerning this submittal, please telephone C. H. Whit temore at ' (615 ) 843-7210.

Sincere y, Ken Powers Enclosure cc: See page 2 ,

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S U.S. Nuclear Regulatory Commission Page 2-May 23, 1994 cc (Enclosure):

Mr. D. E. LaBarge, Project Manager  ;

U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road-Soddy-Daisy, Tennessee 37379-3624 Regiona1' Administrator.

U.S. Nuclear Regulatory Commission Region II .

3 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711 I

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. i ENCLOSURE J

SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 SPECIAL REPORT 94-05

. I. FIRE DETECTORS - UNIT 2 - FIRE ZONE 371 DescripliDILQL_CDudit.ipn On April 7, 1994, at 2330 Eastern daylight time (EDT), the fire detection instrumentation in Fire Zone 371 was declared increrabic, and Limiting Conditionn for Operation (LCOs) 3.3.3.8 and 3.7.11.2 were entered. A trouble alarm was received on Pyrotronics Panel 630, indicating probicms with the fire detection '

instrumentation (thermal detectors) in the area of Reactor Coolant-Pump (RCP) No. 4 on-Unit 2 in lower containment.

LCO 3.7.11.2 was entered because automatic actuation of the fire suppression in the area was lost. Action (a) of LCO 3.7.11.2 requires an hourly fire watch to be established; however, this could not be accomplished because of ALARA considerations, and the sprinkler system could not be returned to service until the detection system, i.e., automatic actuation, was restored.

Accordingly, the LCO 3.7.11.2 action statement could not be complied with. The LCO 3.0.3 exemption provided by Action (b) was applied after evaluating that continued plant operation was warranted. Therefore, until the detection system could be restored, the containment air temperature was monitored for detection of the presence of fire, at which time'the sprinkler system would have been manually actuated.

Cause_of_Condi. tion The thermal detectors in the area of RCP No. 4 in Unit 2 lower containment brought in the trouble alann on the pyrotronica system. These alarms are supervisory circuits that transmit low currcut signals and monitor the resistance in the detection zone to determine circuit integrity. The .cause for .the trouble alarms could not be determined; however, it is strongly suspected that either a lubrication buildup on the detector contacts or a defective base is responsible for the alarms.

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In accordance with LCO 3.3.3.8 Action. Statement (a), the Unit 2 containment ' compartment air temperature was monitored at least once every hour until the detectors could be restored to operable status. A work request'was initiated to repair.the detectors. l The operational parameters of the detectors were. checked and-found 1 l

to be acceptable.. The LCOs were exited at 1100 EDT.on May 5, 1994.

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II. AUXILIARY BUILDING GAS TREATMENT SYSTEM (ABGTS) FILTER HOUSING SPRINKLER SYSTEM DnEI1Plion of Condition On April 16 at 0835 EDT, with Unit 1 in Mode 2 coming out of a refueling outage and Unit 2 in Mode 1, the fire protection sprinkler system in the ABGTS filter housing area was declared inoperable, and LC0 3.7.11.2 was entered. During.a regular performance of a fire protection surveillance, one of the sprinkler heads within the ABGTS filter housing was determined to be damaged and not in the normally closed position. The sprinkler head was still capable of performing its intended function; however, the actuation of the system was changed to manual to avoid inadvertent water damage to the charcoal-filters. A work request was written to repair or replace the damaged head.

Because of the location of the sprinkler head, i.e., downstream of the charcoal filter bank, repairing the head would require the removal of the charcoal filter assemblies. The filters are scheduled to be replaced within the next year; therefore, the decision was made not to replace the sprinkler head at this time.

CRESC_Rf_Candition The cause of the broken sprinkler head is unknown.

Corrently3_ Action In accordance with LCO 3.7.11.2 Action Statement (a), an hourly. '

fire' watch was established and will be maintained until the sprinkler head is repaired or replaced. A backupffire suppression system, i.e., fire hoses, is available. The sprinkler system with the one head damaged is still available to be manually actuated by the fire brigade should the fire detection system or hourly fire watch determine that a fire exists and that the actuation is ,

necessary. The damaged sprinkler head will be corrected during the filter-replacement activity.

III. FIRE HOSE STATION IN THE ESSENTIAL RAW COOLING WATER (ERCW) i BUILDING 'I Destin11on_nLCandition  !

On April 15, 1994, at 1016 EDT, with Unit 1 in Mode 2 coming out 1 of a refueling outage and Unit 2 in Mode 1, the fire protection hose station on Elevation 720.0 of the ERCW building ("B" train side) was taken out of service, and LCO 3.7.11.4 was entered.

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Cause oLCondition The hose station'was taken out of service because it was inside the clearance boundary of a work request associated.with the maintenance of strainers. The maintenance work duration exceeded the TS allowable timeframe for a fire hose station'to be out of-service.

Cattentire._Attlan In accordance with LCO 3.7.11.4 Action Statement (a), an.

equivalent capacity fire hose was routed to the area in case.of.an cruergency (f rom the operable "A" train side). The additional fire hose will remain intact until the strainer work is completed'and the "11" train fire hose station is returned to service.

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