ML20084U841

Special Rept:On 910318,determined That Triaxial Response Spectrum Recorders of Seismic Monitoring Sys Did Not Meet TS 3.3.3.3 Required Measurement Range of 1-20 Hz.License Amend Will Be Submitted to Reflect Correct Ranges

ML20084U841
Person / Time
Site:	North Anna
Issue date:	04/18/1991
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
91-205, NUDOCS 9104230065
Download: ML20084U841 (2)

Text

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l . YlltOINIA RI.ECTHIC AND l'OWElt COhil%NY 4 Ricnwioun,Vnmixir enco April 18, 1991 United States Nuclear Regulatory Commission Serial No. 91 205 Attention: Document Control Desk NAPS /CSW/TAH R5 Washington, D.C. 20555 Docket No. 50-338 License No. NPF 4 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT NO.1 SEISMIC MONITORING INSTRUMENTATION TECHNIC AL SPECIFICATION 3.3.3.3 SPECI AL REPORT On March 18, 1991, station personnel determined that the Triaxial Response Spectrum Recorders of the Seismic Monitoring System do not meet the Technical Specification required measurement range of 1-30 Hz. Failure to meet this measurement range caused the instruments to be considered technically inoperable.

Subsequently, the Action Statement for Technical Specification 3.3.3.3 was entered.

Since this Action-Statement requires a Special Report for seismic monitoring instrumentation inoperable for more than thirty days, this event is reportable pursuant to Technical Specification 6.9.2.

We have Investigated this problem and determined that our May 27,1986 license amendment request (issued as Amendment 80), which established the current measurement range requirements of the Triaxial Response Spectrum Recorders, was in error. -This request did not conform to the specifications of the existing instrumentation or to the Updated Final Safety Analysis Report (UFSAR) Chapter 3, Desian Criteria. Appendix A, Comoliance With Safety Guides. which confirmed our compliance, with several exceptions, to Regulatory Guide 1.12, Instrumentation fqr Earthouakes. One exception provided in that appendix is the Triaxial Response Spectrum Recorder frequency measurement range of 2-25.4 Hz instead of the 1-30 Hz range specified in the regulatory guide.

When the amendment containing the modification to the appendix was submitted during the development of the original FSAR, the change of the response range, stated in the exception, was inadvertently omitted in updating the component descriptions currently in section 3.7.4.5 of UFSAR Chapter 3. This omission resulted in an incorrect measurement range being specified in the license amendment request.

The recorders, although inoperable pursuant to the Technical Specification definition, are capable of performing their design functions and comply with the requirements of Regulatory Guide 1.12, as modified by our stated exceptions, fgt7/

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• • Dochet No. 50-338 serial No. 91 205 page 2 of 2 To reconcile this discrepancy, we will correct Section 3.7.4.5 of the UFSAR to agree with the exceptions to RG 1.12 as stated in UFSAR Chapter 3 Appendix A. We will also submit a license amendment to reflect the correct instrument measurement ranges for Triaxial Response-Spectrum Recorders in Technical Specification 3.3.3.3, Table 3.3 7 ltems 4a 4d as determined by the UFSAR Chapter 3 Appendix A.

If you have any questions, please contact us.

Very truly yours, c

]f ' 1 W. L. Ste art Senior Vice President Nuclear Attachment pc: U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident inspector North Anna Power Station

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