ML20077E251

Special Rept:On 941124,accelerograph Sensor Inoperable for More than 30 Days.Seismic Recorder XR-VA-105 & Accelerograph Sensor XE-VA-105 Declared Inoperable on 941025.Loose Power Cable to Seismic Record XR-VA-105 Tightened

ML20077E251
Person / Time
Site:	Limerick
Issue date:	12/05/1994
From:	Boyce R PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9412120203
Download: ML20077E251 (3)

Text

- ~ . . .. . - - . . - - . , . - - . - . .. . - ,

Ra'asrt W. 81oyce

. '* . Plant Manager- - 4 ~ - -

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Limerick Generating statort

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< PECO ENERGY ecco '"e<av c en>"v Limenck Generating Stahon PO Box. 2%0 Sanatoga PA 19464 0920 215 3271200 Ext. 2000 UFSAR 3.7.4 T.S. 6.9.2

' December 05, 1994 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 Inoperability of-the Seismic Monitoring Instrumentation for More Than 30 Days This Special Report is being submitted pursuant to the  !

requirements of Limerick Generating' Station (LGS),. Unit 1 i and Unit 2 Technical Specifications (TS) Section 6.9.2.as

required by the LGS Updated Final Safety Analysis Report (UFSAR) Section 3.7.4, " Seismic Instrumentation." The LGS UFSAR Section 3.7.4 requires that with one or more of the required seismic monitoring instruments inoperable for_more than 30 days, a Special Report must be prepared and submitted within 10 days outlining the cause of the

-malfunction and the plans for restoring the instrument (s) to operable status. ,

On October 25, 1994, with both units operating at full power, Instrumentation and Controls (I&C) technicians were performing Surveillance Test (ST) procedure ST-2-036-600-0,

" Seismic Monitoring - Triaxial Time - History

, Accelerometers / Recorders (XE-VA-102/XR-VA-102, XE-VA-103/XR-i VA-103, XE-VA-104/XR-VA-104, XE-VA-105/XR-VA-105,.XE-VA-106/XR-VA-106 and Triaxial Seismic Switch (XSH-VA-001))

Functional Test." During the test the I&C technicians identified that the seismic recorder XR-VA-105 was not receiving a signal from the accelerograph sensor, XE-VA-105.

On October 25, 1994, at 1410 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.36505e-4 months <br />, Operations personnel

declared the seismic recorder XR-VA-105 and the

! accelerograph sensor XE-VA-105 inoperable.

I ~

1200 941212O203 941203

{DR ADOCK 05000 52 p) #

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'4 December 05, 1994 Page 2 Initial troubleshooting, as suggested by the vendor, identified that the problem existed with the accelerograph sensor XE-VA-105, which is located inside the Unit 1 Primary Containment. Since Unit I was at full power, and the Primary Containment was inerted with nitrogen, I&C personnel concluded that the necessary troubleshooting to determine the exact cause of the malfunction would have to be postponed until the next appropriate Unit 1 outage. On November 24, 1994, the accelerograph sensor was inoperable for more than thirty days, requiring the submittal of a Special Report.

On November 25, 1994, after I&C technicians had completed work on a second unrelated seismic recorder, XR-VA-104, a decision was made to re-inspect the system associated with the inoperable seismic recorder XR-VA-105. Further troubleshooting identified that the inaccessible sensor was not the cause of the malfunction, but rather a loose power cable to the seismic recorder XR-VA-105. The power cable was part of a modification to the seismic monitoring system that was' completed in September 1994. On November 25, 1994, the power cable was tightened, and the seismic recorder XR-VA-105 and the accelerograph sensor XE-VA-105 were satisfactorily tested and declared operable.

No seismic events occurred while the seismic recorder and accelerograph sensor were inoperable. The remaining seismic ,

monitoring instruments which monitor the response of the plant to a seismic event were and remain available to sense, alarm, record, playback, and analyze seismic data from the.

remaining three (3) seismic sensors. Since the accelerograph sensor XE-VA-102 is the only alarming sensor, and it was always operable, the Main Control Room operators would have been alerted to a seismic event from the available normal seismic alarms and indications. Operations personnel are trained to respond to these alarms and/or indications in accordance with Special Event (SE) Procedure SE-5, " Earthquake." Therefore, the actual and potential consequences of this event were minimal.

If you have any questions or require additional information, please contact Mr. Jim Kantner at (610) 718-3400.

Very truly, young n -

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bo DBN:cah cc: T. T. Martin, Administrator Region I, USNRC N. S. Perry, USNRC Senior Resident Inspector, LGS

a l De'c ember 05, 1994 1 Page 3 bbc: D. M. Smith - 63C-3 W. H. Smith, III - 63C-3 D. R. Helwig - SMB1-1 J. A. Muntz - SSB3-1 J. L. Kantner - SMB3-1 J. Doering, Jr. - 63C-5 J. B. Cotton - 51A-1 C. A. Mengers - SSB4-3 J. G. Hufnagel - SMB3-2 G. A. Hunger, Jr. - 62A-1 T. A. Shea - GML3-A Commitment Coordinator - 62A-1 DER BRP Inspector - SMB3-1 Correspondence Release Point - SMB1-2 l

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