05000327/LER-1989-034, :on 891215,leak Identified from Fitting on Vol Control Tank Level Transmitter & Auxiliary Bldg Evacuated, Preventing Fire Watch Patrol from Entering Bldg for Hourly Rounds.Fitting Tightened

:on 891215,leak Identified from Fitting on Vol Control Tank Level Transmitter & Auxiliary Bldg Evacuated, Preventing Fire Watch Patrol from Entering Bldg for Hourly Rounds.Fitting Tightened

ML19354D894
Person / Time
Site:	Sequoyah
Issue date:	01/16/1990
From:	Bynum J, Hipp G TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-034, LER-89-34, NUDOCS 9001230218
Download: ML19354D894 (4)

LER-1989-034, on 891215,leak Identified from Fitting on Vol Control Tank Level Transmitter & Auxiliary Bldg Evacuated, Preventing Fire Watch Patrol from Entering Bldg for Hourly Rounds.Fitting Tightened

Event date:
Report date:
3271989034R00 - NRC Website

text

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.TENNESCEE VALLEY AUTHORITY 6N 38A Lookout Place January 16, 1990 I

U.S. Nuclear Regulatory Conunission ATTN Document Control Desk

- Washington, D.C.

20555 Gentlemen TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT UNIT 1 - DOCKET NO.

50-327 - FACILITY OPERATING LICENSE DPR LICENSEE EVENT REPORT (LER) 50-327/89034 The enclosed LER provides details of an event wherein an increased airborne activity level in the auxiliary building resulted in suspension of the hourly

' fire watch patrol and subsequent noncompliance with Technical Specification 3.7.12.

This' event is being reported in accordance with 10 CFR 50.73, paragraph a.2.i.

Very truly yours.

TENNESSEE VALLEY AUTHORITY w-R. Byn Vice President L

Nuclear Power Production Enclosure cc (Enclosure):

Regional Administration U.S. Nuclear Regulatory Commission i

Office of Inspection and Enforcement i

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101 Marietta Street Suite 2900 Atlanta, Georgia 30323 INPO Records Center Institute of Nuclear Power Operations 1100 circle 75 Parkway Suite 1500 Atlanta, Georgia 30339 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy Tennessee 37379 9001230218 900116 PDR ADOCK 05000327

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"' Increased airborne activity in the auxiliary building resulted in the suspension of fire watch patrols and subsequent noncompliance with Technical Specifications 3.7.12.

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At 1533 Eastern standard time (EST) on December 15, 1989, with Unit 1 at 100 percent power and Unit 2 at 80 percent power, the hourly fire watch patrol through the auxiliary building could not be completed because of increased levels of airborne radioactivity.

At 1430 EST a leak was identified from a fitting on a Unit 1 volume control tank (VCT) i Isvel transmitter. At 1500 EST entry into the auxiliary building was restricted, and at 1525 EST, the auxiliary building was evacuated. As a result, the fire watch patrol was not allowed to enter the auxiliary building for the hourly rounds required by Action Statement (a) of Limiting Condition for Operation 3.7.12.

Personnel were allowed to roturn to the auxiliary building at 1800 EST when air samples showed airborne activity h:d returned to an acceptable level, and the hourly fire watch patrol was resumed.

The root cause of this event was the VCT level transmitter leak, which was the source of the l

cirborne activity. The corrective action taken to eliminate the source of the airborne l

ectivity was to isolate the VCT level transmitter and tighten the leaking fitting. A work request was written to replace the fitting.

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Description of Event

t At 1533 Eastern standard time (EST) on December 15, 1989, with Unit 1 in Mode 1 at 100 percent power, 2.235 pounds per square inch gauge (psig), 578 degrees Fahrenheit (F), and Unit 2 in Mode 1 at 80 percent power, 2,235 psig, 568 degrees F, the hourly.

fire watch patrol through the auxiliary building (EIIS Code NF) could not be completed b3cause of increased-levels of airborne radioactivity. Higher than normal dose rates w;re first detected at 1415 EST in the Unit 1 Elevation 690 penetration room. At 1630 EST a leak was identified from a sample cap fitting on a Unit 1 volume control tank (VCT) level transmitter (1-LT-62-129A).

The VCT is a holding and processing tank for tha chemical and volume control system (EIIS Code CB). The Unit 1 operator was notified cf the leak, and arrangements were made for instrument mechanics to isolate the level trcasmitter. At 1500 EST entry into the auxiliary building was restricted, and at 1525 EST the auxiliary building was evacuated. As a result, the fire watch patrol was not allowed to enter the auxiliary building for the hourly rounds as required by Limiting Condition for Operations (LCO) 3.7.12.

The VCT level transmitter was isolated, cnd the leaking fitting tightened. A work request has been written to replace the fitting.

The appropriate radiological surveys were made, and air sampics were taken and l

cn21yzed. Personnel were allowed to reenter the auxiliary building at 1800 EST, and the h:urly fire watch patrol was resumed.

Cause of Event

i Tha immediate cause of this event was the failure to complete the required hourly fire patrol because of an increase in the level of airborne radioactivity in the auxiliary building. This condition represented an ALARA (as low as reasonably achievable) concern and access to the area had been restricted.

Th3 root cause of this event was the VCT level transmitter fitting leak that was the source of the airborne activity. The threads on the fitting.had deteriorated or been damaged causing the sample cap to leak.

Annlysis of Event This event is being reported in accordance with 10 CFR 50.73, paragraph a.2.1, as an ep; ration prohibited by technical specifications because the action requirements of LCO 3.7.12 were not met.

Tho hourly fire watch patrol was being performed as required by Action Statement (a) of LCO 3.7.12 because of nonfunctioning fire barriers and as required by commitments to maintain hourly fire watches until certain Appendix R modifications are completed during th3 Cycle 4 refueling outage for each unit. Although the auxiliary building was not visually inspected for fires during the interval from 1533 to 1800 EST, automatic fire dstectors and fire suppression systems were in service and operable during this time.

Th refore, there was no significant degradation in the overall level of fire protection at the plant.

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.m w= ace amawnri Currective Action The immediate action taken was to restrict entry to and subsequently evacuate the cuxiliary building as a conservative protective action.

The corrective action taken to oliminate the source of the airborne activity was to isolate the VCT level transmitter cnd tighten the leaking fitting. A work request has been written to replace the fitting.

Personnel were allowed to return to the auxiliary building when air samples showed airborne activity had returned to an acceptable level.

Additional Information

There have been 36 previous reported occurrences of a failure to perform required fire watch patrolst however, only three of these occurrences were caused by personnel access r:strictions resulting from high airborne activity levels. These three occurrences are datalled in LER 50-327/88028, 88031, and Special Report 88-11.

Because this airborne ovent resulted from unexpected equipment degradation, corrective actions for previous events could not be expected to have prevented this event.

Crmmitments None.

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