ML20101M701

Requests Approval for Use of Closed Circuit Television to Satisfy Unit 1 TS Requirements for Hourly Fire Watch as Compensatory Measures for Inoperable Fire Barrier,Per NRC Bulletin 92-001

ML20101M701
Person / Time
Site:	Limerick
Issue date:	07/01/1992
From:	Beck G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-92-001, CON-NRC-92-1 IEB-92-001, IEB-92-1, NUDOCS 9207090009
Download: ML20101M701 (3)

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a PIIILADELPIIIA ELECTRIC COMi%NY NUCLEAR GROUP llEADQUARTERS 955 65 CIIESTPRBROOK llLVD.

WAYNE, PA 19087 5691 (215) 640-6000 i

July 1, 1992 NUCLEAR ENGINELRlho & $LRVICES DEPARTMENT Docket Nos. S0-352 50-353 License Nos. NPF-39 NPF-85 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk l

Washington, DC 20555

SUBJECT:

Limerick Generating Station, Units 1 and 2 Request for Approval for Use of a Closed Circuit Television to Satisfy Technical Specifications Fire Watch Requirements Gentlemen:

The purpose of this letter is to request approval for the use of a closed circuit television (CCTV)(to satisfy Limerick Generating Station (h as a LGS), Unit 1, Technical Specifications TS) requirements for an hourly fire watc compensatory measure for an inoperable fire barrier.

NRCBulletin(NRCB)No.

92-01, " Failure of Thermo-Lag 330 Fire Barrier System to Maintain Cabling in Wide Cable Trays and Small Conduits Free from Fire Damage," issued on June 24, 1992, 4

equested licensees to promptly identify the areas of the plant which have Thermo-Lag 330 fire barrier material installed to protect either small conduits or aide cable trays that provide safe shutdown capability, and to implement compensatory measures, such as fire watches, in accordance with either plant TS or an operating license condition for an ino>erable fire bar+ier.

Based on our review of the plant areas which contain 11ermo-Lag 330, one such area is Fire Zone 458 (i.e., the Neutron Monitoring System area for LGS, Unit 1, Room No. 406).

This area contains vertical sections of 24 inch wide cable trays that are encapsulated in Thermo-Lag 330 fire barrier material to protect cabling required to provide safe shutdown capability.

These fire barriers were declared inoperable based on the information in NRCB 92-01.

TS Section 3.7.7, Action a. requires establishing an hourly fire watch patrol when a fire area contains an inoperable fire barrier with operable fire detectors-on at least one side of the inoperable barrier. As an immediate compensatory measure on June 25, 1992, an hourly fire watch was first established outside the Neutron Monitoring System area based on initial dose rate-considerations, and then eventually inside this area following subsequent evaluation of the dose rates by Health Physics personnel. The dose rate was a concern because room No. 406 is radiologically controlled as a locked high radiation area, i.e., due to_ potential dose rates in excess of 1,000 mR/hr when the Transversing In-core Probes (TIPS) are withdrawn from their shields. Currently, LGS Unit 1 is in an outage, with startup scheduled for July 2, 1992. As a result, the general area dose rates in this room range from 2 to 20 mR/hr with the TIPS in their shields.

However, h

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t O.'S. Nuclear Regulatory Commission July 1, 1992 j.

Document Control De<'t Page 2 i,

4 during Unit l startup and power operations, the TIPS are withdrawn from the shields and dose rates in room No. 406 rise to 54 R/hr.

The estimated accumulated i

dose the hourly fire watches would receive over a day during and following a TIP operation would be 1125 mR. Additionally, the general area dose rates in room No.

406 will be IR/hr during )ower operation. An alternative to a person performing an hourly " fire watch in t11s room would be considered good "As Low As Reasonably i

Achievable (ALARA) practice.

Therefore, as interim compensatory measures, until l

the final corrective actions to restore the inoperable fire barriers to an operable status are implemented, we request approval to use a CCTV to perform an hourly fire watch of room No. 406. The viewing monitor would be located just outside the locked high radiation area where the general area dose rate would be 2 l

to 20 mR/hr.

Use of a CCTV to satisfy TS fire watch requirements has previously been approved by the NRC, e.g., NRC approval for New York Power Authority's l

Fitzpatrick plant, dated April 2, 1992.

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The equipment used for the remote hourly fire watch for the inoperable fire barriers in the Neutron Monitoring System area consists of a television camera and 4

The CCTV monitor is an eight (8)g remotely focused, panned, tilted, and a monitor.

9e camera is capable of bein inch diagonal black and white display i

zoomed.

unit.

Testing requirements and acceptance criteria for the camera and monitor are met if the designated fire barriers are clearly visible and positively identified i

on the remote monitor. The camera provides the capability for a person performing-the fire watch to visually monitor-the inoperable fire barrier and the general area surrounding the fire barrier. Regardless of any affects of radiation on thi3 i

equipment, any degradation in video transmission would be-readily detected.

Should-the quality of the video transmission become degraded, the appropriate corrective action will be taken to ensure that the area of concern is maintained under visual surveillance consistent with good ALARA practice.

Fire Zone 45B has a 16 minute equivalent fire severity, comprised primarily of cable trays encapsulated by the Thermo-Lag fire barrier material.

The electrical cabling and jacketing systems used at LGS pass the flame test in i

standard IEEE 383 -1974, "lEEE Standard for Type Test of Class 1E Electric Cables, Field Splices, and Connections for Nuclear Power Generating Stations," dated April 15,- 1974.

lgnition of electrical cabling in cable trays is extremely unlikely in the absence of a fire source external to the cabling, since tests on these cables have shown the progression to a fully develo)ed fire-is retarded by the fire retardant properties impregnated into the ca)1e jacketing.

Additionally, there are no in situ combustible materials located in this-fire arca other than the cabling.in the cable trays encapsulated by Thenno-Lag 330.

e.dministrative controls implemented by Administrative (A) procedures, e.g.,

A-12.2, " Control of Combustible Materials, Flcmmable and Non-flammable Compressed Gases," and A-30, "Housekee)ing,'? prohibit storage and limit.the-amount of

combustibles permitted in t1e plant, and. ensure that potential fire hazards are kept to a minimum in all areas of the plant including those areas where Thermo-Lag fire barriers are required to-meet-fire protection safe shutdown requirements.-

Therefore,.instanteneous spreading of a fire throughout this fire area is highly-unlikely. Also, this fire area contains smoke detection and automatic areaction.

sprinkler systems that use heat detectors and fusible links, and water lose-stations are-located outside the area.. Therefore in the unlikely event'.that a fire should occur in this area, it would.be detected early and most likely contained by-the installed fire protection equipment before it could challenge the Thermo-Lag fire barrier system.

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' ' 0.5. Nuclear Regulatory Commission July 1, 1992 Document Control Desk Page 3 l

The us'e of a CCTV reduces personnel radiation exposure incurred during an j

hourly fire watch.

Posting an hourly fire watch to monitor the inoperable fire barriers in the Neutron Monitoring System area by using a CCTV provides a level of protection equivalent to the posting of an hourly fire watch in the room.

Locating the fire watch outside of the high radiation area using the CCTV does not l

reduce the level of protection required by TS, and conforms with accepted ALARA practices.

Since Unit 1 is currently scheduled f e startup from the outage on l

July 2, 1992, we request immediate action by the NRC in response to this request.

]

In addition to Fire Zone 45B on LGS Unit 1, Fire Zone 67 (i.e., the Pipe Way i

area for LGS, Unit 2, Room No. 368) was another area containing Thermo-Lag 330 1

fire barrier material.

As a result, the fire barriers in this room were decle. red 1

inoperable. This area does not have fire detection.

In this situation, o continuous fire watch must be posted to satisfy TS requirements; however, posting of a continuous fire watch in this room would not be consistent with good ALARA practices due to the general area dose rate in this room.

Accordingly, this is to inform the NRC that a continuous fire watch was posted at the doorway to the area, and through the use of a mirror, is able to continuously view the general area containing the inoperable fire barriers, if you have any questions, please-do not hesitate to contact us.

1 Very truly yours,

/f W

OL G. J.

, Manager Licensing Section cc:

T. T. Martin, Administrator, Region I, USNRC j

T. J. Kenny, USNRC Senior Resident Inspector, LGS i

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