ML20151Z035

Special Rept:On 880707,containment Fire Detection Instrumentation Left Out of Svc for Greater than 14 Days. Cause Can Not Be Determined Until Plant Shutdown & Reactor Missile Shield Removed to Access Detector Wire

ML20151Z035
Person / Time
Site:	Yankee Rowe
Issue date:	08/19/1988
From:	St Laurent N YANKEE ATOMIC ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
FYR-88-112, NUDOCS 8808290142
Download: ML20151Z035 (3)

Text

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YANKEE ATOMIC ELECTRIC COMPANY r.i.ouon. tars ><2<s2e:

Star Route, Rowe, Massachusetts 01367

.Yauxes ..

August 19, 1988 FYR 80-112 U.S. Nuclear Regulatory Commission Document Control Desk Wauhington, DC 20555

Subject:

Special Report:

Containment Fire Detection Instrumentation Out of Service for Greater Than 14 Days (T.S. 3.3.3.4)

Dear Sir:

In accordance with Technical Specification 3.3.3.4.b and 6.9.6.e. the attached Special Report outlining the actions taken, the cause of the inoperability and the plans and schedule for restoring the instrument to operable status is hereby submitted.

Very truly yours, ,

A% Wv Normand N. St. Laurent P1 ant Superintendent ELM / elm Enclosure cca L3] NSARC Chairman (YAEC)

[1] Institute of Nuclear Power Operations (INPO)

[1] USNRC. Region !

ef, Resident Inspector 8808290142 880819 PDR ADOCK 05000029 S PNU fSO W -.

. .g YANKEE ATOMIC ELECTRIC COMPANY Page 1 FYR 88-112 ACTION TAKES On 7/7/88, at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br />, a fire detection alarm was received in the control room. The source of the alarm signal was found to be from the Vapor Container linear heat detection instrumentation. The alarm condition was indicated to be in the area cf the reactor control rod control and rod position indication cable runs. A Vapor Container entry was made to investigate the alarm. The investigation of the area revealed no abnormal conditions. A review of the Technical Specifications was conducted. A determination was made that the remaining operable detection zone, located in another area, would meet the minimum requirements for operability and no further action was necessary.

Although the Technical Specification requirements were apparently saticfled a means of monitoring the area for fire conditions was pursued. On 7/8/98, at 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br />, a temporary change was completed that installed two digital ohmmeters to the linear thermal detector to provide continuous indication in the control room. A decrease in the ohmic values registered on the ohmmeters is used to indicate potential fire conditions. This change substitutes a visual monitoring method for the continuous electronic monitoring and audible alarm provided by the detection system. Because of ALARA and personnel hatch degradation concerns the ohmic values are recorded and evaluated hourly, by an approved procedure, in lieu of an hourly fire watch patrol of the area.

A Technical Specification change is being formulated and will be submitted for review and approval. The change will eliminate the ambiguity that presently exists with the minimum required detectors ir the Vapor Container and will address compensatory measures to be taken if the' zone is not operable.

C_AlglE OF T HE _ INOPERAllIL I TY The root cause of the inoperability can not be determine.d until the plant is shutdown and the reactor missile shield removed to allow access the detector wire. It is felt that there was a weak point in the detector wite insulation introduced either during the manufacturing or installation process. This is the first failure of this nature associated with this system since it was installed approximately eight years ago, t

a s YANKEE ATOMIC ELECTRIC COMPANY- Page 2 FYR 80-112 RCWEJ}pLE FOR HESTORATION The detection system will be returned to normal operation at the end of our ne y: t refueling outage which 's scheduled to be January 1989. The detector wire is normally removed at the beginning of every refueling and reinstalled at its completion.when the control rod cables-are removed and installed. Our refueling outage is scheduled to begin on November 12, 1989, therefore, the total length of time that the zone will be operated in the degraded mode is approximately four months.

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