ML20077B575

Special Rept:On 890724,seismic Monitoring Sys Declared Inoperable to Facilitate Relocation of Free Field Monitor. Efforts to Troubleshoot & Repair Sys Unsuccessful.Schedule for Restoration of Sys Listed

ML20077B575
Person / Time
Site:	Braidwood
Issue date:	04/30/1991
From:	Checca A COMMONWEALTH EDISON CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 9105150014
Download: ML20077B575 (2)

Text

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t Mf,a v Mr. A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Commission 799 Roosevelt Road-Rill Glen Ellyn,11 60137

Subject:

Braidwood Station Unit 1 Seismic Monitor NRQDocket Nosm50-456__

Refernce: (a) NUREG-1276, Technical Specification

Dear Mr. Davis:

Braidwood Station Technical Specification 3.3.3.3, for seismic monitors states that with one or more of the required seismic monitors inaperable for more than 30 days, prepare and submit a special report to the commission, pursuant to specification 6.9.2 within 10 days outlining +he cause of the malfunction and the plans for restoring the instrument (s) to operable status. This letter is being submitted in accordance with this Technical Specification requirement for the free field seismic monitor.

The Seismic Monitoring System was declared inoperable on July 24,1989 for the relocation of the free field monitor. This relocation was necessary to accomodate the construction of a new training facility. The relocation also necessitated an amendment to the Technical Specifications and bases. This amendment was received at Braidwood Station on 4/18/91. The Seismic Monitoring System had been considered inoperable until receipt of the amendment.

l Beginning in January,1991, the Time History Accelerograph has not performed reliably when attempting to record internal test signals. Efforts to troubleshoot and repair the unit at the station have proven to be unsuccessful. After consultation with the vendor, Terra Technology, it has been determined that the Digital Cassette Accelerograph (DC A 300P) and the Response Spectrum Analyzer would be I returned to the vendor for repair. The units were shipped to the vendor the week of j 4/22/91.

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Mr. A. Be1 Davis April 30,1991 Two options are being considered to restore the system to an operable status, They are:

a. Repair the DCA 300P unit, or

b. Replace with the solid state DCA 300 R Ram Deck Recorder The proposed schedule for restoration of the system is as follews:

4/29/91 Receive vendor quote for repair time and costs.

5/06/91 Determination made to repair or replace.

5/13/91 Vendor initiates action to repair or replace.

6/03/91 Vendor ships equipment to Braidwood.

6/10/91 Installation 6/17/91 Testing 6/24/91 System Returns to Service.

Please direct any questions concerning this submittal to this office.

Sincerely, ht ,C &R.

Allen R. Checca, Nuclear Licensing Administrator cc: R.M. Pulsifer, Project Manager - NRR S. Dupont, Resident inspector - Braidwood Document Control Desk - NRR l

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