ML20011E634

LER 90-005-00:on 900209,six Limitorque Corp Gear Operators, Model HBC-1,found to Contain Defect in Casting of Limit Stop Housing.Housings Machined to Remove Excess Matl.Item Reportable Per Part 21.W/900214 Ltr

ML20011E634
Person / Time
Site:	Beaver Valley
Issue date:	02/14/1990
From:	Noonan T DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-90, REF-PT21-90-027-000 LER-90-005, LER-90-5, ND3MNO:2026, PT21-90-027-000, PT21-90-27, NUDOCS 9002220059
Download: ML20011E634 (9)

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Beaver: Valley Power Station,-Unit No. 2

> Docket No. 50-412, License No. NPF-73 LER 90-005-00 L:  ;

o United-States Nuclear Regulatory Commission DocumentEControl Cesk' Washington, DC 20555 Gentlemen:

In accordance with Appendix A, Beaver Valley Technical Specifications, the following Licensee Event Report is submitted:

H LER 90-005-00, 10 CFR 21.21.b.1, " Casting Defect in Limit

'Stop Housing".

Very.truly yours,.

k$. h u ft-T. P. Noonan General Manager Nuclear Operations Cj Attachment

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, F2bruary 14, 1990-0 ND3MNO:2026 Page two, cc: Mr. William T. Russell Regional Administrator United States Nuclear Regulatory Commission Region 1.

i 475 Allendale Road King of Prussia, PA 19406 C. A. Roteck, Ohio Edison Mr. Peter Tam,.BVPS Licensing Project Manager United States Nuclear Regulatory Commission Washington, DC 20555' J. Beall, Nuclear Regulatory Commission, BVPS Senior Resident Inspector .

Dave Amerine Centerior Energy 6200 Oak Tree Blvd. a Independence, Ohio 44101 INPO Records Center l Suite 1500 1100 Circle 75 Parkway Atlanta, GA 30339 G. E. Muckle, Factory Mutual Engineering, Pittsburgh Mr. J. N. Steinmetz, Operating Plant Projects Manager Mid Atlantic Area Westinghouse Electric Corporation Energy Systems Service Division Box 355 Pikggburgh, PA 15230 l Ts .i American Nuclear Insurers c/o Dottie Sherman, ANI Library i The Exchange Suite 245  ;

270 Farmington Avenue i Farmington, CT 06032 q Mr. Richard Janati Department of Environmental Resources P. O. Box 2063 16th Floor, Fulton Building $

Harrisburg, PA 17120 Director, Safety Evaluation & Control Virginia Electric & Power Co.

P.O. Box 26666 f One James River Plaza Richmond, VA 23261 j

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),. NRC form 34 U.S. NUCLLD v t UL1 TORY COMM6sSION CPPROVED OMt NO 3190 010e r

LICENSEE EVENT REPORT (LER) ' " N a ' * ' ' 8 '

faACILITY NAME tip '

DOCE$1 NUMetR (71 PAM G

' Beaver Valley Power Station, Unit 2 015101010lJt3TT 1 l0Fl 017 flTLE to: -

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Casting Defect in Limit Stop Housing EVlNT DATE Ill LER NUMetR tai REPORT DATE (7) OTHER F ACILITIt$ INVOLVED (S)

MONT H DAY YE A04 YEAR MONTH DAV YEAR F ACILIT V N AMES DOCK 41 NUMBERi$)

BVPS - Unit 2 015l0l0l0 14 1 l2

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,,,,,,,,, THis RtPORT is sunMirito PURSUANT 70 tHE R60UinsuiNTS O, 30 C,R t tenne m e, ,. e ra, ene.mei nu N I'I 1 to 402M 20 4061st 50.73teH2Hevi 7171M 20.4061sH1Hil 50 38(eHD 50.73taH2Het 73.7Het no, 1, 0 i0 .0 mnuM

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20 4061aH1Hilal 80.73tei12Het 60.7 Sie H2 HediH Al J86Ai to 406(eH1Hwl 60.73LeH2Hul 50.734sH2Hv416H81 to 4044sHUM 50.73taH2 Hied So,73(sit 3Hal LICENSEE CONT ACT FOR THis LtR (tti NiMI it LtPHONE NUMBER Thomas P. Noonan, General Manager Nuclear Operations 411 12 614 13 1-11 12 1518 COMPLEf t ONE LINE FOR E ACH COMPONENT F AILURE DESCRISIO IN THIS REPORT H31

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LE CAust sv5 TEM COMPONENT jC F REPORTA LE B B11 2l01 1 Ll 2 3 0l0 Y l i i l l l l l 1 l l I I I I I I I I I I SUPPLEMENT AL REPORT EXPECTIO ti4l l MONT H OAY YEAR SutMsSSION Yt$ llf pet torrysere iMPtCTED $v$64tS5 TON DA TEI ko l l l Aos, A ACs wr M ,a wa., i . . .am.. ww r ,,u.e ,,,,r. wa. rn..,,w s, a n s, This report is being submitted under a 10CFR21. Six Limitorque Corporation gear operators, model HBC-1, were found to contain a defect in the casting of the limit stop housing. These six operators are used at Beaver Valley for automatic opening discharge valves in the safety related river water (service water) system.-The subject valve operators were manufactured in 1971. The affected valves normally use open and close limit switches to cease valve motion. The casting defect, located on the limit stop housing, causes the valve motion to cease prematurely in the open direction. This occurs because excessive torque, required to overcome the defect, actuates the installed torque switch and stops further valve travel. The defect was corrected, during the Seventh Refueling Outage, by machining the excess material. There were no safety implications as a result of this event. A river water pump remains continuously in service with its discharge valve open. The defect alone will not cause a loss of river water cooling. Two trains of Auxiliary river water were available at all times. Operation of other '

valves, of the same or similar model, were reviewed and no safety concerns were identified.

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NRC Foran 3084 ' U.S NUCLE A3 KEIULifs3Y COMMitSloN LICENSEE EVENT REPORT (LER) TEXT CONTINUATION m aoviooveNo.siso-oix (XPIRES: 8 '31/88 F Ar:ltlTV NAME (t)

• DOCKLT NUMBER (2) LER NUMSIR (6)- PAGE (3) nw vsa- w,n Betver Valley Power Station, Unit 2 o l5 l 0 l 0 l 0 l 313 l 4 910 -

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0l0 0 12 OF 0l7 itKT fr more space e meured, arme eetwst NRC form J86CsJ 1171 DESCRIPTION During the Seventh Refueling Outage, BARTS (Butterfly Analysis and Review Test System ) was used to troubleshoot a persistent problem with a safety related river water pump discharge valve. During pump starts and testing, the discharge-valve would trip during its stroke from the closed to open position on excessive torque.

Repair efforts had centered around the torque switch. Increasing the setting and replacing the switch failed to resolve the valve tripping. BARTS testing identified the motor as supplying equal torgue in both open and close directions. When coupled to the gear train, however, the opening torque was greater than the closing ,

torque. Upor inspection of the gear train, it was noted that the limit stop housing contained an area of larger surface where the bearing contacts the housing. This larger area also contained rub marks where the inner race of the bearing had contacted the housing where, normally, the outer race is the only portion of the bearing which makes contact with the housing ( See figure 1 ).

l This larger surface area was caused by excessive material in what should be a recess in the limit stop housing. The excess material had been machined flat by the manufacturer and now made contact See figure 2 ). When the with valvethe wasinner stroked raceinofthe theopen bearing direct (ion, the worm shaft would force the inner race of the bearing against the limit stop housing and increase the torque required to stroke the valve open.

Inspections of the remaining five river water pump discharge valves identified the existence of the defect in all five limit stop housings, in varying degrees. A maintenance history review noted that premature tripping of the valves was common to four of the six valves, two valves experiencing no problems.

It was later noted that the identical part number (Limitorque Corporation 60-014-007) for the limit stop housings is also used in gear operator models HBC-2 and HBC-3. A maintenance history review did not identify any stroking difficulty with any of the HBC-2 and HBC-3 valves, ggrow 3... .u... m , ns.- no ner o w o

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TEKT (# moe spew h mewmf wse edAemner 44C Form Juiu w tin SAEETY IMPLICATIONS There were no safety implications identified at Beaver Valley. One train of river water is always in service. Two redundant auxiliary river water. pumps are available, in addition to the three pumps of.

the normal system. The defect alone could not have caused a total loss of river water.

Of all valves with the HBC-1,2, or 3 gear operators, a review  !

determined that the valves are either normally open, or stroke i closed to their safety related positions, or are tested during i surveillances under normal flow conditions. 1

~ Beaver Valley Unit II construction was initiated after the period j when the valves were manufactured. A review determined no valves 1 at Unit II are affected.

l A generic safety issue arises based on the application of the gear operators, models HBC-1,2, and 3, at other plants. The valves may not stroke fully open to permit design flows to be delivered to their respective components.

COMPANY SUPPLYING BASIC COMPONENT ,

i Limitorque Corporation l 1

LOCATION OF BASIC COMPONENTS CONTAINING DEFECT Six safety related river water pump discharge valves were found to contain the defect. The Beaver Valley mark numbers are MOV-1RW-102A1, A2, B1, B2, C1, and C2.

CORRECTIVE ACTION i

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1. The six river water pump discharge valves limit stop housings l were machined to remove the excess material. This was completed during the seventh refueling outage.

2. A review of the operating and maintenance history of the remaining HBC-1,2, and 3 model valves was conducted by the Engineering and Electrical Maintenance Departments. No indication of a defect was found based on proper valve operation and testing when the valves were stroked to the open position with a differential pressure across the disk.

3. Engineering review has determined that Beaver Valley Unit II does not have the affected gear operators installed, y ( k I id38 S. i F 's 6. ' 'ti

i- l NRCPerg30$A U.S. NUCLEJ.R S EQULATORY COMM10SION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION mRovto ove No. mo-oio4 EXPIRES: 8/31/98 F ACILITV NAME til =

DOCEET NUMBER (2) LIR NUMBER (6) PAGE(31

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ADVICE AND ADDITIONAL INFORMATION

1. Based on conversations with the vendor, Plants utilizing models HBC-1,2,3 gear operators, or having replacement parts, which were manufactured prior to 1975 may be susceptible to the described failure.

2. Increasing the torque switch setting in response to premature tripping may mask the defect if the increased setting allows the gear operator to overcome the defect. Persistent torque switch tripping, even at the higher settings, will be indicative of a potential defect. This will only occur during the opening stroke of the valve.

3. Inspection programs, when applied, will be able to identify the defect by rub marks on the limit stop housing where the inner race of the worm shaft bearing contacts the limit stop housing.

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PARTS LIST PC. NO. DESCRIPTION PC. NO. DESCRIPTION PC. NO. DESCRIPTION 1 HOUSING: 8 POINTER 15 WORM SHAFT "O" RING 2 HOUSING COVER 9 POINTER CAP 16 STOP SCREW COVER-3 END CAP 10 END & THUR CAP GASKET 17 STOP SCREW & LOCKSCREW -

, 4 THRU CAP 11 HSG, COVER GASKET 18 HEX STOP NUT 5 DRIVE SLEEVE & WORM GEAR 12 DRIVE SLEEVE BUSHING 19 LIMIT STOP HOUSING 6 WORM SHAFT 13 WORM SHAFT BEARING 20 CAP LIMIT STOP HSG.

7 SPLINE ADAPTER 14 DRIVE SLEEVE "O" RING 21 LIMIT STOP HSG. GASKET FIGURE 1 o

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