ML20151P107

Special Rept:On 880602,six Triaxial Time History Accelerographs Declared Inoperable Due to Inadequate Calibr Surveillance Tests.Tests Revised to Incorporate tilt-table Testing of Accelerographs

ML20151P107
Person / Time
Site:	Limerick
Issue date:	07/12/1988
From:	Mccormick M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 8808090189
Download: ML20151P107 (4)

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3882098490 PHILADELPHIA ELECTRIC COMPANY LIMERICK GENER ATING STA flON P. O. BOX A S AN ATOG A. PENNSY LV ANI A 19464 July 12, 1988 Mr. William T. Russell Administrator Region I U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Subject:

Special Reporting Requirement for Inoperable Seismic Monitoring Instrumentation at Limerick Generation Station

Reference:

Technical Specification 3.3.7.2 and 6.9.2

Dear Mr. Russell:

This special report is being submitted pursuant to the requirements of Limerick Technical Specifications 3.3.7.2 anc' 6.9.2 which state:

SEISMIC MONITORING INSTRUMENTATION:

3.3.7.2 The seismic monitoririg instrumentation shown in Table 3.3.7.2-l* shall be OPERABLE.

4.3.7.2.1 Each cf .he above required seismic monitoring inst aments shall Sc demonstrated OPERABLE by the performance of the 'ANNEL CHECK, CHANNEL FUNCTIONAL TEST, and CHANNEL CAI TTION operations at the frequencies shown in Table 4.3.7.2-1.

APPLICABILITY: At all times.

8808090189 880712 PDR ADOCK 0500 g[j ,

. Mr. William T. Russell, Administrator Page 2 3882098490 ACTION:

a. With one or more of the above required seismic monitoring instruments inoperable for more than 30 days, prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within the next 10 days outlising the cause of the malfunction and the plans for restoring the instrument (s) to OPERABLE status.

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b. The provisions of Specifications 3.0.3 and 3.0.4 are not applicable.

SPECIAL REPORTS 6.9.2 Special Reports shall be submitted to the Regional Administrator of the Regional Office of the NRC within the time period specified for each report.

DESCRIPTION OF EVENT:

On June 2, 1988 six (6) triaxial time history accelerographs, which comprise a portion of Limerick's Seismic Monitoring System, were declared administratively inoperable due to inadequate 18-month calibration surveillance tests. The triaxial tine-history accelerographs produce a record of the time varying acceleration at the sensor location. This data is used directly for analysis and comparison with reference information.

The 18-month calibration surveillance tests were developed based on instructions originally supplied in vendor manuals which required the use of a system calibration key switch for instrument calibration. On June 2, 1988, following a conversation with the system supplier, Kinematics Inc., it was discovered that the vendor has revised their requirements and that the system calibration key switch is no longer used for calibration of the accelerographs. The vendor now recommends accelerograph calibration using a known acceleration input to determine the instrument's sensitivity with the calibration key switch used as a functional check. This has not been performed during previous 18-month calibration surveillance tests.

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, .' Mr. William T. Russell, Administrator Page 3 3882098490 CONSEQUENCES OF THE EVENT:

There was no impact on normal operations, as a result of this condition. The capability for the control room to receive notification of a seismic event is unaffected by the administratively inoperable instrumentation because the control room receives signals from other components of the seismic monitoring system which have been calibrated properly and therefore accurately sense seismic activity.

In the event of seismic activity exceeding the Operating Basis Earthquake acceleration level at the containment base slab, administrative controls require a plant shutdown. The plant's ability to adequately analyze the acceleration level of the containment base slab immediately following a seismic event is affected by the administratively inoperable accelerographs. A proper calibration of the containment base slab acceletograph would be first required to determine the base slab acceleration level. Following this calibration the measured response spectra could then be compared to the Operating Basis Earthquake response spectra to ascertain the severity of the seismic event. If the measured response spectra exceeded the Operating Basis Earthquake spectra additional seismic event damage analysis vould be required. Therefore, the remaining accelergraphs would require calibration in order to perform a detailed analysis of the seismic event.

CAUSE OF T 'jT:

The cause for the declaring the six (6) triaxial time-history accelergraphs administratively inoperable was deficient calibration surveillance tests. Originally supplied vendor manuals denote "calibration capability by means of a key switch".

Limerick developed 18-month calibration surveillance tests utilizing the key switch. Recent conversations with the vendor revealed the key switch operation as a functional check of the accelerographs, and that tilt-table testing, which induces acceleration inputs on the sensors, should be used for the 18-month calibrations.

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f.' Mr. William T. Russell, Administrator Page 4 3882098490 CORRECTIVE ACTIONS

The applicable 18-month calibration surveillance tests are being ravised, in accordance with the vendor's new requirements, to incorporate tilt-table testing of the accelerographs. These procedures will be revised by August 31, 1983. Upon approval, these surveillance tests will be performed on the four(4) accelerographs which are accessible at power.before December 31, 1988. The remaining two(2) accelerographs, which are mounted in the drywell, will be calibrated properly during the next outage which permits sufficient drywell accessibility.

Should you require additional information, please do not hesitate to contact us.

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G; Very truly yours, M. J. McCormick, Jr.

Plant Manager RWG:lc cc: Addressee T. J. Kenny, USNRC Senior Resident Inspector bec: 4;C N A F McNd51E,NP.Z-IS26 21? b t

J. W. Gallagher - S25-1 i E. P. Fogarty - S7-1 W. M. Alden - S7-1 J. T. Robb - S7-1 i R. H. Moore - S7-3 Commitment Coordinator - S7-1 C. R. Endriss/DBN - LGS A2-2 R. W. Degregorio - LGS A3-1 D. Sherman, ANI DAC 1

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