ML20066F719

Special Rept:On 901102,sensor Channel Malfunctioned.Cause Unknown.Sensor Channel Will Be Repaired by Next Refueling Outage (Mar 1991)

ML20066F719
Person / Time
Site:	Braidwood
Issue date:	12/24/1990
From:	Checca A COMMONWEALTH EDISON CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 9101240124
Download: ML20066F719 (2)

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A, 1400 Opus Place V ~

Downers Grove, Illinois 60515 Qy a

December 24, 1990 HI0c!TY Raging

[f C iEEE l()cqvt.drl5VW Mr. A. Bert Davis ,

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Regional Administrator U. S. Nuclear Regulatory Commission '

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ga Region III nug 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

Braidwood Station Unit 1 Loose Parts Monitoring System-Special Report

Dear Mr. Davis:

i Technical Specification 3/4.3.3.8 requires that a special report be I submitted to the NRC. The purpose of this report is to delineate the cause of sensor channel malfunction, if known, and outline the steps required to correct the malfunction.

Sensor channel 1VE-LM009 had previously been declared inoperable and removed from service. Furthermore, sensor 1VE-LM010 was declared inoperable '

due to noise generated by the sensor. A preliminary investigation indicated that the noise was due to malfunctioning sensors in the Unit I containment.

These sensors are both located on the C Steam Generator inlet / outlet plenum.

The failure of both sensors at a natural collection point (Steam Generator C inlet / outlet plenum), constitutes an inoperable system. Therefore, the LCOAR was entered on November 2, 1990. Technical Specification' Action Statement 3.3.3.8a requires a special report be submitted to the NRC Regional Administrator, if the channel remains inoperable more than 30 days.

During the next refueling outage (March, 1991) the Instrument Maintenance Department, assisted by Technical Staff will-enter the Containment in order to determine the exact cause of the sensor malfunction. The failed sensor channel will be repaired at that time. Also, during the outage, the 18 month surveillance will be performed to ensure that the Loose Parts Monitoring System (LPMS) is functioning properly.

In the interim,-the LPMS detectors are 611gned to the following sensors: 1VE-LM002, 3, 5, 8, 12, 18, and 19. 'hese sensors correspond to the reactor vessel (bottom and head) and one each at 'he inlet plenums of Steam Generators A, B, and D and the lower narrow range taps of Steam Generators B and C respectively. These detectors, coupled with the required daily operating surveillances, for audible detection of a loose part, will adequately detect any loose part occurrence untti the sensors at the_ inlet plenum of C can be repaired.

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Mr. A.B. Davis December 24, 1990 Please direct any questions to this office.

Very truly yours, fhjf #"

Allen R.Checca Nuclear Licensing Administrator i cc: R. Pulsifer -NRR H.Shafer - RIII Resident Inspector - Braidwood NRC Document Control Desk ARC /cag ZNLD/686 l

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