ML20115D898

Special Rept:On 920909,discovered That Channel 1 (Longitudinal Axis of Three Orthogonal Axes) of Accelerograph Sensor Failed Test Criteria.Cause Not Yet Determined.Maint Work Request Initiated on 920922

ML20115D898
Person / Time
Site:	Limerick
Issue date:	10/16/1992
From:	Doering J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9210210218
Download: ML20115D898 (2)

Text

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4 T.S. 6.9.2-

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T.S. 3.3.7.2

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, PHILADELPHIA ELECTRIC COMPANY LIMERICK GENER ATING STATION P. O. DOX A S AN ATOG A. PENNSYLV ANI A 19464 (215) 327-1200- exv. 3000 J. DO E RIN G. JR.

u o. . . 7'.'J .".'1"."., .. ... October 16 , 1992 Docket Nos 50-352 50-353 License Nos. NPF-39 NPF-85 U.S. Nuclear' Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Limerick Generating Station, Units 1 and 2 Special Report for the Inoperability of a Seismic Monitoring System Instrument for~More Than 30 Days.

REFERENCE:

Technical Specificat ir- sections 3.3.7.2 and 6.9.2 This Special Report is beir s submitted pursuant to the requirements of Technical SP'.vifications (TS) Section 6.9.2 as required by TS Section 3.'./.2, " Seismic Monitoring

' Instrumentation." TS Section 3.3.7.2 requires that with one or more of the required Seismic Aonitoring System (SMS) instruments inoperable for more than 30 days, a Special Report must be prepared and submitted within 10 days outlining the cause of tha malfunction and the plans for restoring the instrument (s) to operable status.

On September 9, 1992, with both units at 100% power, Instrumentation & Controls ~(I&C) technicians were performing Surveillance Test (ST) Procedure ST-2-036-426-0, " Seismic Monitoring - Triaxial Time History Recorders (XR-VA-102, XR-VA-103, XR-VA-104, XR-VA-105, XR-VA-106) Calibration / Functional Test." While procedure ST-2-036-426-0 was in progress,-I&C personnel discovered that channel 1 (longitudinal axis of three orthogonal axes) of accelerograph sensor ::E-VA-105 to recorder XR-VA-105 failed the functional loop check-test crite:ia and was declared inoperable.

Troubleshooting identified that the problem existed with the accelerograph sensor XE-VA-105, which is located inside the Unit 1 Primary Containment on a reactor piping support (i.e., Main Steam Line 'D' elevation 313'). On September 21, 1992, the vendor for the accelerograph sensor, Kinemetrics, Inu., was contacted and solicited for advice on the prcbable cause of the accelerograph sensor failure. The vendor recommended that L. furthe: troubleshooting of the accelerograph sensor inside the , g 210031' 921o2to21e 921016 ce PDR ADOCK,0bOOO352 .

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, . Unit 1 Primary Containment would be necessary to identify the-root cause of the problem.-.The Unit 1 Primary Containment has been inerted with nitrogen and has been in Operational Condition 1 (Power Operations)-at 100% power since July 15, 1992.

Therefore, the accelerograph sensor was not accessible to perform corrective maintenance.- On September-22, 1992, a maintenance work action request was initiated to repair-the accelerograph sensor during the next Unit 1 outage of sufficient duration which allows accessibility to thE' Unit 1 Primary Containment. On October 9, 1992, the accelerograph sensor had been inoperable for more than 30 days, requiring the submittal of a Special Report.

No seismic events have occurred to date since the accelerograp" sensor was determined to be inoperable. The balance of tne SMS which monitors the response of the plant to a seismic event was and remains available to sense, alarm, record, playback, and analyze-seismic data from a balance of 26 seismic sensors. -The Main Control Room operators vould have been alerted to a seismic event from the available normal seismic alarms and s

indi. cations. Operations personnel are trained to respond to thece alarms and/or-indications in accordance with Specia Event (SE) Procede re SL-5, " Earthquake." Therefore, the actual and potential consegur ;es of this event are minimal.

The exact cause of this malfunction has yet to be determine.d, but has been traced to-the longitudinal axis of the accelerograph sensor.. This accelerograph sensor is a new unit, and was

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installed and successfully tested on' March 14, 1992, Since the accelerograph sensor is located inside the Unit 1 Primary Containment, which is presently inaccessibte, further troubleshooting and any corrective maintenance will be performed 3 during the next Unit-1 outage of sufficient duration which allows accessibility to the Unit 1 Primary Containment. A plaa for g corrective actions to prevent recurrence will tus determined at that time.

If you have any questions, please contact Mr. Gil J. Madsen at (215) 327-1200.

Sincerely. ~'

ml $ L.

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Y DMS:cah Attachment cc: T. T. Martin, Administrator, Region I, USNRC T. J. Kenny,-USNRC Senior Resident Inspector, LGS 9

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