ML20129C819

Special Rept:On 960826,Unit 1 Began Receiving Loose Parts Alarm in Mcr.Caused by C Loop Cold Leg Loop Stop Isolation Valve.Se Performed by Westinghouse

ML20129C819
Person / Time
Site:	Braidwood
Issue date:	10/08/1996
From:	Tulon T COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9610240125
Download: ML20129C819 (3)

Text

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, . Commonwealth I:dison Company p liraidwust Generating Station

, Route *l. !kix H 4 liracesille, 11.60107 % 19 Tel H 15-iS8 2H01 October 8,19%

United States Nuclear F.egulatory Commission Attention: Document C ontrol Desk Washington, D. C. 205f 5-0001

Subject:

Braidwood Station Unit I loose Parts Monitoring System Special Report, Docket No. STN 50-456

References:

(a) NUREG-1276, Technical Specifications, Braidwood Station, Unit Nos. I and 2 (b) Regulatory Guide 1.133, Loose-Part Detection Program for the Primary System of Light-Water-Cooled Reactors, Rev.1, May 1981 Braidwood Station Technical Specification 3.3.3.8 Action (a) requires that with one or more Loose-Part Detection System channels inoperable for more than 30 days, a Special Report shall be prepared and aubmitted to the Commission within the next 10 days. In accordance with Specification 6.9.3, the cause of the malfunction and plans for restoring the channel (s) to operable status must be outlined. Pursuant to these Specifications, the enclosure provides a report regarding th: inoperability of a Loose Part Detection System initiated on September 13, i 1996.

Please direct any questions regarding this submittal to Doug Houston, Braidwood Station l Licensing Coordinator, extension 2511.

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. Tulon

/ tation Manager Braidwood Nuclear Station Attachment cc: A. B. Beach, Regional Administrator - Region III ' l R. R. Assa, Braidwood Project Manager - NRR 4 ,.

l C. Phillips, Senior Resident Inspector - Braidwood // -

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9610240125 961008 PDR ADOCK 05000456 S PDR 5

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Braidwood Station Unit 1 Loose Part Detection System Inoperable for greater than 30 days

Description:

At 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br /> on August 26,1996, Unit I began receiving Loose Parts alarms.in the Main Control Room. After a two-week investigation period, which included taking  ;

Unit 1 offline on September 6,1996, Comed concluded that the most probable source of the metal-to-metal impacts causing the Loose Parts alarms was the C Loop Cold Leg Loop Stop Isolation Valve (LSIV). A 50.59 Safety Evaluation was performed by Westinghouse and a Braidwood On-Site Review was conducted that approved restart ,

of Unit 1 on September 9,1996. The low level impacts within the LSIV are causing l repetitive Main Control Room loose parts alarms. This will continue until the source j of the impacts can be eliminated. Braidwood Station recognizes that the nature of the I repetitive alarms may result in control room personnel becoming desensitized to the alarming condition. Comed has taken actions to prevent this from occurring, and also ,

to be able to detect another loose part, if one actually exists. Therefore, the existing 1 in-plant system has been realigned and a portable Loose Parts Monitoring system has  ;

been installed in Unit 1.

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Actions Taken:

The Loose Part Monitoring (LPM) detectors are currently aligned to the following sensors:

IVE-LM003 Reactor Vessel Bottom 1VE-LM006 1 A SG Cold Side IVE-LM007 IB SG Hot Side IVE-LM009 1C SG Hot Side IVE-LM016 ID RCP SealInjection IVE-LM020 1 A SG Upper Level Tap IVE-LM021 ID SG Lower Tap i 1 VE-LM024 ID SG Upper Tap This alignment eliminates the repetitive alarms associated with the LSIV and it is '

expected to detect another loose part, if one actually existed. While the Loose Parts Monitoring system has been declared inoperable due to the above stated alignment (Reactor Top not aligned), the system is still fully functional. Thus, a valid impact resulting in an alarming condition will be detected in the Main Control room to allow operators to take the appropriate actions. The in-plant system is also being checked shiftly by operating personnel for additional assurance that no other conditions exist that would prevent a valid impact from going undetected.

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4 The currently installed portable LPM system is monitoring the alarming channels,

which include the reactor top, to ensure the " constrained" part within the C Loop Cold Leg LSIV has not moved. The portable LPM system is not connected to the j annunciation system in the Main Control room and thus, the repetitive alarms do not become a distraction to the operators.

Plans and Schedule for Restoring the Loose Part System to Operable status:

Currently, plans are being developed to address inspecting the C Loop Cold Leg LSIV. It is expected that the next refueling outage, which is scheduled to begin I

March 29,1997, will provide an opportunity to inspect the LSIV and to correct the l cause of the impacts. Also during this outage, all sensors will be calibrated and

!' repaired if necessary, and the routine 18-month surveillance will be performed to ensure the Loose Parts Monitoring System is functioning properly. In the interim, the

LPM sensors will be aligned for optimum detection of a potential loose part and to 4 continue to monitor the existing condition in the C Loop Cold Leg LSIV. l J