PNO-IV-88-028, on 880409,33-inch Piece of Steel from MSIV Gate Guide Assembly & Broken Fasteners Found Caught by Basket Strainer Upstream of Throttle Valve.Licensee Plans to Disassemble Both MSIVs & Insp Performed

PNO-IV-88-028:on 880409,33-inch Piece of Steel from MSIV Gate Guide Assembly & Broken Fasteners Found Caught by Basket Strainer Upstream of Throttle Valve.Licensee Plans to Disassemble Both MSIVs & Insp Performed

ML20151U656
Person / Time
Site:	Waterford
Issue date:	04/13/1988
From:	Chamberlain D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-88-028, PNO-IV-88-28, NUDOCS 8805020117
Download: ML20151U656 (2)

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April 13, 1988 r >

"' ' PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PN0-IV-88-28

'This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the

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Region IV staff on this date.

FACILITY:-Louisiana Power and Light Company Licensee Emergency Classification:

Waterford 3 Steam Electric Station Notification of Unusual Event

.Taft. Louisiana Alert DN: 50-382 Site Area Emergency General Emergency X Not Applicable

SUBJECT:

MAIN STEAM ISOLATION VALVE DAMAGE On April 9, 1988, day 8 of the second refueling outage when the No. 1 Main Turbine Throttle Valve was opened for routine inspection, the licensee found a piece of steel 33 inches long by 2 1/2 inches wide by 1 3/8 inches thick which had been caught by the basket strainer upstream of the throttle valve. The piece was slightly bent and broken at one end. A few broken fasteners were also found.

The piece of metal had a part number stamped which identified the piece as part of the gate guide assembly for one of the Main Steam Isolation Valves (MSIVs).

As a result, the licensee plans to disassemble both MSIVs, even though it believes the source of the metal is MSIV B (MS-1248). Parts from MSIV B would have a straight shot through the crossover to No.1 Turbine Throttle. Almost half of the 200 feet of the 40-inch up,tream main steam header was inspected for more parts, and none have been found.

I As this was the first time the turbine throttle valve was opened, the parts could have broken loose at any time from the first power run in 1985. The licensee has had no significant operating problems with the MSIVs except on December 11, 1987, when an air solenoid valve failed on the electric-hydraulic actuator for MSIV B during a routine quarterly cycling test. This caused an abnormal closure and resultant reactor trip. The valve functioned satisfactorily

,- after the solencia valve was replaced. When the plant was shut down for the

refueling outage on April 2, 1988, both MSIVs A and B exhibited normal characteristics upon closure.

The MSIVs at Waterford-3 are 40x30x40 Class 600 gate valves manufactured by the W-K-M Valve Division of ACF Industries. The Resident Inspectors are monitoring the licensee's actions. The Vendor Program Branch in NRR has been kept informed ,

of this event.

The licensee does not plan to issue a press release.

Region IV received notification of this occurrence by the senior resident inspector on April 11, 1988 . Region IV has informed NRR.

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t This information has been confirmed with a licensee representative.

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CONTACT: D. D. Chamberlain (FTS 728-8249)

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