ML20044D651

LER 93-013-00:on 930415,determined That as-found Setpoint for Seven SRVs Not within TS Limit.Caused by Lift Setpoint Discrepancies of Srvs.Review of Setpoint Data Will Be performed.W/930515 Ltr

ML20044D651
Person / Time
Site:	Cooper
Issue date:	05/15/1993
From:	Gardner R, Myers J NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CNSS933111, LER-93-013, LER-93-13, NUDOCS 9305200111
Download: ML20044D651 (5)

Text

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- COOPER NUCLEAR STATION Nebraska Public Power District "&"E a??@is""^n"^ ""'

CNSS933111 May 15, 1993 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. .20555 [t i

Dear Sir:

r Cooper Nuclear Station Licensee Event Report 93-013, Revision 0, is forwarded as an attachment to this letter. ,

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Sincerely, .,

t R. L. Gardner "

Plant Manager i

RLG/ju Attachment .j cc: J. L. Milhoan G. R. Horn ,

j J. M. Meacham  !

l R. E. Wilbur V. L. Wolstenholm i

-D. A. Whitman f INPO Records Center NRC Resident Inspector  !

R. J., Singer- j CNS Training i CNS Quality Assurance 190020 fgf i 9305200111 930515 :I l I

i PDR -ADOCK O5000298-i S .pyg .

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C Form 396 U 8. NUCLEAR KEGULATORY COMMrstION ,

APPT.OVED OM) NO.3150 4104

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LICENSEE EVENT REPORT (LER)

FACILITY NAME (1) DOCKET NUMSER (2) PAbi Os Cooper Nuclear Station 0 l5 l 0 l0 l 0 l2 l9 l8 1lOFl014 TITLE tel Safety / Relief And Safety Valve Setpoint Variance Not Within Technical Specification Limits EVENT DATE (El LER NUMBER 46) REPORT DATE (7) OTHE R F ACILITTEE INVOLVED (S)

MONTH DAY YEAR YEAR ( l [g MONTH DAY YEAR F ACiUT V h AMES DOCKET NUMBERIS) 0l5l0l0l0; ; l

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0l4 1l5 9 3 9 l3 0l1l3 0l0 0l 5 1l5 9 l3 0l5l0 togog l l l

,,,,,,,,, Twis RtPORT is susurTTED eURsuaNT TO Tut REOUiREMENTs OP 10 CFR t eCne<* .ne e, m.,e er ene verM-=,s (11:

MODEM) i N 20.A02<mi 20.aosiet 30.73teH2H+ > 73.71 r=i R 13 4051sH1Hi} $0.36(cH11 60.73teH2Hw) 73.71tel (103 01010 20 40swHiim 20.406(eH1HIH) 502swH2 50.73(eH2Hil 1 50.73wH2n*m

_ gggg 366A1 50.73(eH2Hv611HA) 20,406 teH1Hevi 50.73teH2 Hill 50.73teH2HvillH51 20 405(ell 1Het 50.731eH2iM) 60.73(eH2Hs)

LICENSEE CONTACT FOR This LER {12)

NAME TELEPMDhf NUMBER AREA CODE John R. Myers 410 I ? 812151-13181111 COMPLETE ONE LtNE FOR E ACH COMPONENT F AILURE DESCRIBED IN THtt REPORT (13)

CAUSE SYST EM COMPONENT M E '

E O NPR CAUSE SYSTEM COMPONENT

1. O' 'OR A LE }

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X SIB l lRlV TI01210 Y I l t t  ! I I X SlB l lRIV D l 21413 Y I l l l l l l EUPPLEMENTAL REPCET EXPECTED (146 MONTH DAY YEAR SUBMISStON YE$ fit yet, comosen EXPECTED SVRMIS$10N DATE] NO l l l asTR ACT w.m ra oa wece, a. m m ames., s.nowce re-rw. o,nea nsi While the plant was shut down for the 1993 Refueling Outage, testing of eight Safety / Relief Valves (S/RVs) and two Safety Valves (SVs) was conducted at the Westinghouse Western Service Center, Banning, California. The as-found setpoint for seven S/RVs was not within the Technical Specification limit of i 11 psi.

Additionally, the setpcint for one SV was not within the Technical Specification limit of i 13 psi.

Review of the test data indicates the S/RVs generally displayed performance characteristics typical of the industry-wide problems associated with corrosion bonding of the pilot disc. To date, the root cause and corrective action for this industry-wide problem remains unresolved. Also noted were performance characteristics typical of labyrinth seal induced friction. The failure of the safety valve is considered random setpoint drift.

The valves are being inspected, refurbished and satisfactorily retested before their return to the site. Nebraska Public Power District is continuing to monitor the industry-wide efforts sponsored by the BWR Owners Group to resolve the corrosion bonding setpoint drift phenomena. It is anticipated that pilot discs of an improved material selection will be installed in selected valves during the next refueling _

outage.

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tenC Form 3064 U.S. NvCLEAn EEOULATORY COMMleBION

. LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Arenoveo ous no momo.

vacturv =ame su oocatr =vmeta m ten uvusen m rxrints: ersues pao im l

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Cooper Nuclear Station 0 l5 l0 l0 l0 l219 l8 9I3 0l1l3 OF 010 0l2 0 l4 i

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A. Event Description l L

I' Testing of Safety / Relief Valves (S/RVs) and two Safety' Valves (SVs) conducted at the Westinghouse Western Service Center, Banning, California, revealed the e following as-found setpoint variance: l Valve Valve Serial Limiting Safety As-Found f Type Number Number System Setting Setooint Variance  !

S/RV 71ARV 384 1100 11.psig 1167 psig + 6.1 %  :

S/RV 71BRV 380 1100 11 psig 1123 psig + 2.1 % -[

S/RV 71CRV 383 1090 i 11 psig 1145 psig .+ 5.0 % 1 S/RV 71ERV 386 1080 i 11 psig 1001 psig ' +11.2 %  !

S/RV 71FRV 379 1090 1 11 psig 1242 psig +13.9 % .;

S/RV 71GRV 382 1100 i 11 psig 1125 psig + 2.3 %  !

S/RV 71HRV 385 1090 i 11 psig 1128 psig + 3.5 % '

SV 70CRV BL2461 1240 1 13 psig 1210 psig - 2.5 % j i

Safety / Relief Valve 71DRV (Serial Number 387) was found to be within the ,

Technical Specification limit with a set pressure of 1078 psig. Safety-Valve .,

70BRV (Serial Number BL2462) was found to be at the Technical Specification limit of 1227 psig.  !

r B. Plant Status ,

Shutdown for the 1993 Refueling Outage which commenced March 5, 1993. f 6

C. Basis for Report t

r The performance of the S/RVs indicates they are susceptible to a condition l causing nr:1tiple independent components to become inoperable in a single  ;

system designed to mitigate the consequences of an accident,~ reportable in ,

accordance with 10CFR50.73(a)(2)(vii). .}

D. Cause

[

t A review of the as found test data indicates the lift setpoint discrepancies i of the safety relief valves displayed performance characteristics typical of I industry-wide problems associated with corrosion bonding of the pilot disc. l Various S/RVs also showed indications of minor labyrinth seal induced -l friction. The failure of the SV is considered random setpoint drift. The -

performance of the valves is consistent with that generally experienced by the industry. j i

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~stC Perm 3550 UA NCCLEOR QEGULOVDRV COMMIS$10N

, UCENSEE EVENT REPORT (LER) TEXT CONTINUATION caovgo aue No. am-om j

, EXPtRES: $/3110 F

F AC4LITY KAME 44 DOCKET WUMBER Di PAGE g3)

LER NUMBER (E)

SE[$QAL ?> q[(*gp VEAn Cooper Nuclear Station 0 ]5 l0 l0 l0 l219 l8 9I3 0I1l3 010 Ol 3 OF 0 l4 rExi w n.a uma s m = .an mac re,m seuwm E. Safety Sirnificance i

An analysis performed by General Electric with one S/RV lifting at.1250 psig  !

and the remainder lifting at 1210 psig (+ 10 percent) indicates that the l Reactor Coolant system integrity was not affected by the as found conditions. l This analysis considered the additional loadings which would be imposed by the  ;

increased flow resulting from the higher discharge pressure and the margins to thermal limits. The as-found conditions are enveloped by this latest analysis. The reduced lift setpoint of the SV is an operational concern, rather than a safety concern. Substantial margin remained between the normal operating pressure of 1000 psig and the as found setpoint of 1210 psig.

F. Safety Imolications The safety implications of this event are fully described in the section above.

G. Corrective Action The S/RVs and SVs are being inspected, refurbished, and satisfactorily a retested at the test facility. It should be noted that with respect to the S/RVs, their performance is considered to be consistent with industry l experience. A review of the as found setpoint data for the S/RVs indicates an [

overall decline in performance. This decline appears to be related to  :

specific valves and independent of time in service while at power. Additional ,

evaluation of this data will be performed to determine possible contributors- l and potential resolutions, including interim actions to reduce the corrosion bonding phenomena. j Nebraska Public Power District is continuing to monitor the industry-wide efforts sponsored by the BWR Owners Group to resolve the corrosion bonding i setpoint drift phenomena. One of the corrective actions being pursued is a i catalytic platinum stellite pilot disc to reduce corrosion in the pilot seat.

area. The new discs are presently being pursued for installation in spare valves. It is anticipated that these upgraded valves will be installed during l the next refueling outage. [

H. Similar Events l t

LER 91-015 - Safety / Relief and Safety Valve Setpcint Variance not Within i Technical Specification Limits l LER 90-003 - Safety / Relief Valve and Safety Valve Serpoint Variance Not  !

Within Technical Specification Limits i LER 89-015 - Safety / Relief Valve Setpoint Variance Not Within Technical {

Specification Limits i

• D.S. CPoi 1988-620-589:00070,. ;

wnC FomM 366A 19G3)

. . .. - +

ZMC f orsa assa - U S. NUCLEAR R ESULATORY COMMitstOd

, UCENSEE EVENT REPORT (LER) TEXT CONTINUATION AreRovoo oms No aiso-eio. l EXPIRES: t/31/98  ?

8 ACsLITV NAME til DOCKET NUMBER (2) LER = UMBER (Si

, PAGE(31

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i Coopet Nuclear Station 9I3 0l1l3 OF 0 l5 l 0 l 0 l 0 l2 1918 - -

0 10 Ol4 0 l4 rcxt a - w .<ie ,N,une i.,,as4wim i i

H. Similar --(Continued) i LER 88-009 -

Setpoint Variance and Operability Concerns Associated with Safety Relief Valves and Safety Valves Discovered During Surveillance Testing ,

LER 86-032 - Main Steam Safety Relief Valve Setpoint Drift and Stuck Pilot Valve Inoperability Discovered During Scheduled Valve Testing and Refurbishment LER 85-003 -

Setpoint Drift of Safety and Safety Relief Valves i

L Sunnlemental Infortnation 'f The S/RVs are two stage, Model 7567F Target Rock Safety Relief Valves.

EIIS Component Code - RV.

The SV is a Model 3777QA RT22, Manufactured by Consolidated Valve Corp / Dresser Industries. EIIS Component Code - RV.

EIIS System Code - SB.

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