ML20094L065

Special Rept:On 920204,local Fire Detector Alarm Panel for Fire Detection Zone Was in Trouble Indication Condition. Cause Not Determined.Hourly Fire Watch Patrol Established to Monitor Alarm

ML20094L065
Person / Time
Site:	Davis Besse
Issue date:	03/19/1992
From:	Storz L TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AB-92-0012, AB-92-12, NUDOCS 9203240268
Download: ML20094L065 (2)

Text

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e gggg TOLEDO EDISON A ceme or f.negy C 9www rD 50N PL A ZA

0) MAD! SON Avf NLL TOJDO OH!O 43GSEDOO1 NP40-92-001 AB-92-0012 Docket Number 50-346 License Number NPF-3 March 19, 1992 United States Nuclear Regulatory Commission Document Conttol Desk Vashington, D.C. 20555

Subject:

Special Report Pursuant to Technical Specification 3.3.3.8, Fire Detection Instrumentation Gentlemen:

• This letter provides the Special Report required by Davis-Besse Nuclear Power Station (DBNPS) Operating License, Appendir A, Technical Specification (TS) 3.3.3.H, Fire Detection Instrumentation, when required fire detection lustrumentation is inoperable in excess of fo ; teen days.

On February 4, 1992, "ith the reactor at 100% power (Mode 1), Toledo Edison (TE) identified that the local fire detector alarm panel (C4720A) for fire detection zone (FDZ) 317, containment batch area 585' elevation, was in a "troub]c" indication condition. This class A nmoke detection zone consists

-of twenty-six Cerberus Pyrotronics Model DI-6 ionization detectors which vere installed in the fall of 1991 during the seventh refueling outage.

Since the trouble indication condition could not be reset, FDZ 317 vas declared inoperable and the Action statement for TS 3.3.3.8 was entered.

This Action statement requires the establishment of an hourly fire watch patrol for accessible fire detection zones. Hovaver, because FDZ 317 is inside the reactor containment building and is identified on TS 3.3.3.8 Table 3.3-14 as an inac+$ ssible area, an hourly fire watch patrol was not established in FDZ 11 7 . In that the trouble indication condition for FDZ 317 on fire ~ panel C4720A prevented other trouble indication conditions (but not alatm conditions) on C4720A from being transmitted to the main control room, an hourly fire watch patrol was established to monitor C4720A for additional trouble indication cond1tions. Althougl. the trouble indication condition became intermittent after FDZ 317 vas declared inoperable TE continued to consider FDZ 317 inoperable.

This Action statement also requin , either.the restoration of the inoperable fire detection instrument to an operable status within fourteen days or-the subnission of a Special Report to the Nuclear Regulatory Commission (NRC) within the next thirty days outlining the action taken, the cause of

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inoperatillity, and-the plans and~ schedule for-restoring the fire detection i

-instrument to an operable status.

During troubleshooting actions at C4720A, a monitoring system was heoked up-to the viring associated with the detectors in 12 317. The troubleshooting results indicated a reasonable-likelihood-that t a detector and/or-its

-associated base was failing. Toledo Edison evaluated the time required for troubleshooting and repair along with the expected radiation exposures and determined that the benefits of restoring FDZ 317 to an operable status were

- justified from an As Lov. As Reasonably Achievable (ALARA) program perspective. An action plan was developed to perform a containment entry in ,

Lorder to isolato and replace the failing detector / base.

On February- 21,-1992,. a containment entry was made. The time spent in FDZ 317 was kept at a minimum consistentEvith ALARA practices. One detector base was determined through testing to be inoper.able and was replaced. A new detector vas also installed in the new base. The trouble condition was

• cleared,-and, after several days of monitoring without incident, FDZ 317 was -

declared operable on February 24, 1997. .

The exact cause of detector inoperability can not be detarmined because the Ei noperable detector base can not be decontaminated sufficiently without destroying it to allov shipment to the manufacturer for a cause of failure

' evaluation. .It is being retained on site for further analysis should additional detector failures Andicate a need for root cause analysis.

If:you havelany questions, pleasa contact Mr. R. V. Schrauder, Manager -

Nuclear. Licensing, at (419) 249-2366.

, Very'truly yours, W

LL.i F. Storz .

4 ov M

~

"" Plant: Manager

~KBR/ed cei [A. B. Davis, Regional Administrator, NRC Region III i J. B. Hopkins, NRC/NRR DB-1 Senior Project Manager V. Irvis, NRC Region III, DB-1' Senior Resident Inspector Utility Radiological Safety Board

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