ML20079F630

Special Rept:On 910818 & 0905,Fire Detection Zone A208 & Instruments Declared Inoperable When Subj Zone Panel Went Into Alarm W/No Indications of Fire.Detector Shipped to Vendor for Troubleshooting & Repair

ML20079F630
Person / Time
Site:	Davis Besse
Issue date:	09/25/1991
From:	Storz L TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AB-91-0022, AB-91-22, NP-40-91-02, NP-40-91-2, NUDOCS 9110080223
Download: ML20079F630 (2)

Text

.. -_.-. .- - . - - . -. -.

a s

i; n

^ TOL EDO EDISDN A ceraeror (regy cmpory G I OtSON Pt A7A 300 MADtSoN r,vt NUE rouco. onia 43raum NP-40-91-02 AB-91-0022 Docket Number 50-346 License Number NPF-3 Septcmber 25, 1991 United States Nuclear Regulatory Coumission Document Control Desk Vashington, D. C. 20555 Subj ec t : Special Report Pursuant to Techni. 1 Specification 3.3.3.8, Fire Detection Instrumentation Gentlemen:

This letter provides the Special Report required by Davis-Desse Nuclear Power Station (DBNPS) Operating License, Appendix A, Technical Specification (TS) 3.3.3.8 Fire Detection Instrumentation, when required fire detection instrumentation is inoperable in excess of 14 days.

On August 18, 1991, with the reactor at 71% power (Mode 1) Toledo Edison (TE) identified that the panel for Fire Detection ?one A208 (Containment Annulus) vent into alarm with no other indications of fire. Since there

- was no indicat]on of fire and the panel could not be reset, the zone was declared inoperable. The zone instruments were declared inoperabic and the

- action statement for DBNPS TS 3.3.3.8 was entered. This action statement

-requires the establishment of an hourly fire patrel for the zone. However, due to the inaccessibility of the Containment Annulus because of high radiation levels, houily fire watches were not established until the zone became accessible on August 31, 1991 following plant shutdown for refueling. Technical Specification 3.3.3.8, Table 3.3-14, recognizes this zone as an inaccessible area.

, this~ action statement also requires either the restoration of the

inoperable detector to an operable status within fourteen days or the sulmission of a Special Report to the Nuclear Regulatory Commission within the next thirty days outlining the actio.. taken, the cause of the inoperability and the plans and schedule for restoring the instrument to an

operable status.

.i 9110030223'91092*S PDR ADOCK 05000346 ' h S- PDR h/( '"/') U

<

• o 6

Docket Number 50 346 License Number 11PF-3 NP 02 Page 2 TL- a.'ainment Annulus was inaccessible for the first tvelve days after the file de m. tion zone was determined inoperable = doe to the high radiaticq levels. On the thirteenth day (August 31, 1991), aftet the plant entered flo t Standby (Mode 3) for the refueling outage, access was gained to the i containment Annulus and a single Itre detectot was found to be in an alatmed condition. This detector was cleaned and the sensitivity adjusted, but the fire alarm could not be cleared. On Sentember 5, 1991, a secono detector in the reme fire detection zone alarmed and was also identified as inopetable. _

Since this type ot detector is obsolete and a like-for-like-replacement is ,

not available, the two detectors and their bases (which contain sensing electronics) were temoved and shipped to the vendor for troubleshooting and repali. The vendor vill identify the cause of the failure, attempt to repait the detectors and bases and return them to the CBNPS. Following this deter.nination of the f ailure cause by the vendor, TE vill supplement t his tcport to the NRC. Toledo Edison plans to restore these two fire detectors to operability prior to startup from the current refueling outage. In the interim, TE will maintain an hourly fire watch patrol as a compensatory measute in accordance vi'.h the action statement of Technical Speeiiication 3.3.3.0.

If you have any questions, please contact Mr. R. V. Schrauder, Manager - Nuclear Licensing, at 419-249-2366.

Very ttuly youts,

4. .

, .. f - eq ,,

l. . I' . S t o r z /'

Plant Managet KAS/ed cc: P. M. Byron. NRC Region III, DB-1 Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III J . B. Ilopkins , NRC/NRR DB-1 Senior Project Manager tit ility Radiological Saf ety Board ,

_ - _ _ _ _ - _ _ - _ _ _ _ _ _ - _ _ - _