ML18036B083

LER 92-003-00:on 921027,discovered Failure of Reactor Zone Isolation Dampers to Close.Caused by Failed Solenoid Operated Valve.Outboard Damper Manually Closed by Isolating Air Supply & Bleeding Air Off damper.W/921127 Ltr

ML18036B083
Person / Time
Site:	Browns Ferry
Issue date:	11/27/1992
From:	Conley W, Zeringue O TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-003-04, LER-92-3-4, NUDOCS 9212070116
Download: ML18036B083 (18)

Text

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ACCESSION NBR:9212070116 DOC.DATE: 92/11/27 NOTARIZED: NO DOCKET FACIL:50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH. NAME 'UTHOR AFFILIATION CONLEY,W.A. Tennessee Valley Authority ZERINGUE,O.J. Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-003-00:on 921027,discovered failure of reactor zone isolation dampers to close. Caused by failed solenoid operated .valve. Outboard damper manually closed by isolating air supply 6 bleeding air off damper.W/921127 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ( ENCL 1 SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER),, Incident .Rpt, etc.

NOTES:

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1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POOREPW. 1 1 NUDOCS FULL TXT 1 1 l

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Tennessee Valley Authority, Post Office Box 2000. Decatur, Alabama 35609.2000 O.J. Ike Zertngue Vice President. Browns Ferry Nuclear Plant NOV S V 1992 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

TVA 'BROWNS FERRY NUCLEAR PLANT ( BFN ) UNITS 1 p 2 3 DOCKET NOS ~ 50 2 59 /

260, AND 296 FACILITY OPERATING LICENSE DPR-33'2'8 LICENSEE EVENT REPORT LER-50-296/92003 The enclosed report provides details concerning the failure of two reactor zone isolation dampers to fully cl'ose. Debris in the damper was the apparent cause for the partial closure of one damper., A'failed solenoid valve caused the other damper problem. This report is submitted in accordance with 10 CFR 50.73(a)(2)(vi) and 10 CFR 50.73(a)(2)(v)(C).

Sincerely,

!'g>JJrjfiVC Og J. Zeringue Enclosure cc: See page 2

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9212070116 921127 PDR ADOCK 05000296 PDR

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U.S. Nuclear Regulatory Commission gay P.-, 1932 cc (Enclosure):

INFO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339'aul Krippner American Nuclear Insuxers Town Center, Suite 300S 29 South Main Stree't West Hartford, Connecticut 06107 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, P.O. Box 637 Athens, Alabama 35609-2000 Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 2900 Atlanta, Georgia 30323 Thierry M. Ross U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

II 0 NRC Form 366 u. LEAR REGULATORY CONfISSION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

FACILITY NAHE (1) IOOCKET NUHBER (2) r w r N N TITLE (4) Failure of the reactor zone isolation dampers to close.

V NT P T T F V 0 I REVISIONI FACILITY NAHES IDOCKET NUHBER(s)

I I I I I SEQUENTIAL I I I N

A A HB R A r w I I I I I I I I I I

~i 1 1 2 7 9 2 r w r 0PERATING I ITHIs REP0RT Is sUBHITTED PURsUANT To THE REQUIREHENTS 0F 10 CFR 5:

NODE r m f 1 f20.402(b) )20.405(c) ( )50.73(a)(2)(iv) I I73.>>(b)

POMER ) )20.405(a)( 1)(i ) ]50.36(c)(1) J~)50.73(a)(2)(v) i 73. 71( c)

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LEVEL I I 120.405(a)(l)(ii) I50.36(c)(2) I50.73(a)(2)(vii) (OTHER (Specify in 1 )20.405(a)(l)(iii) ) )50.73(a)(2)(i)(B)( [50.73(a)(2)(viii)(A) Abstract below and in

)20.405(a)( l)(iv) ] (50.73(a)(2)(ii) ) [50.73(a)(2)(viii)(B) Text,'NRC Form 366A) 1 v ill FRTI 12 NAHE

) AREA CODE 1 r i F HP N NT F IREPORTABLEI I I IREPORTABLEI I I I Y TH PNNT MAN F T R T Y PNNT N I I I I I I I D V I I I I I I I I I 4

P N D 14 I EXPECTED I N Y I i sUBHIssIDN I Y f ml P TO B NOT N ABSTRACT (Limit to 1400 spaces, i.e., approximately fifteen single-space typewritten lines) (16)

On October 27, 1992 at approximately 0028 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br />, while performing a scheduled surveillance instruction (SI) to calibrate and functionally test the Browns Ferry Unit 3 reactor building and refueling floor ventilation radiation monitors, the Unit 3 reactor zone outboard, exhaust damper failed to close and the inboard exhaust damper failed to close completely in response to a test generated containment isolation signal. This condition was discovered by the Unit. 3 operator at 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br />. Units 1 and 3 were defueled and Unit 2 was at approximately 89 percent power. This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(vi) due to equipment failures that could cause the release of radioactive material..

The outboard damper failed to close due to a failed solenoid operated, valve. The failure of the inboard damper to close completely was apparently caused by debris caught in the damper.

Immediate corrective actions included manual closure of the outboard damper by isolating the air supply and bleeding air off the damper. The inboard damper operator was disconnected and the damper was cycled manually. The failed solenoid will be examined at a TVA laboratory and by the solenoid vendor. forTVAdebris. will revise damper preventive maintenance activity to include an inspection NRC Form 366(6-89)

Qi NRC. Form 366A U. CLEAR REGULATORY COMMISSION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) (DOCKET NUMBER (2)

I ( SE()UENTIAL t i REVISION J Browns Ferry Uni t 3 I Y N I I I I TEXT (If more space is required, use additional NRC Form 366A's) (17)

I. PLANT CONDITIONS Units and 3 were shutdown and defueled.

1 Unit 2 was in the run mode at approximately 89 percent power.

II. DESCRIPTION OF EVENT A; Event:

On October 27, 1992 at 0028 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> CST, while performing a routine surveillance instruction (SI) (Unit 3 reactor building and refueling floor ventilation radiation monitor [IL3 calibration and functional test), the Unit 3 reactor zone outboard, exhaust damper I:BDMP] failed to close and the associated inboard exhaust damper [BDHP3 failed to close completely in response to a surveillance test generated containment isolation signal.

This condition was discovered by the Unit 3 operator at 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br />.

Limited Condition for Operation (LCO) 3.7.C.2 was entered since the fail.ure of both inboard and outboard dampers to close violates secondary containment requirements. Additionally, refueling zone supply fan 3B failed to trip. All other automatic safety functions performed as expected.

At 1510 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.74555e-4 months <br /> the 3B refueling zone supply fan was stopped by opening its 480V supply breaker. To restore secondary containment, the inboard and outboard dampers were manually isolated at approx.imately 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> and LCO 3.7.C.2 was exited.

. This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(vi) due to equipment failures that could cause the release of radioactive material.

B. Inoper ble S ruc re nn r

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The failure of Unit 3 reactor zone ventilation exhaust inboard isolation.

damper 3-FCO-64-42 to fully close is=believed to,have been caused by debris. caught in the damper. This could not be conclusively determined.

The outboard damper 3-FCO-64-43 failed to close due to its air operated solenoid valve (ASCO MODEL 602-832-3RF) sticking in the open position.

Preliminary examination of the solenoid operated valve (SOV) indicates failure may have been caused by a binding valve stem.

The 3B refueling zone supply fan failed to trip due to a piece of cable tie cord stuck in the breaker control relay plunger.

NRC Form 366(6-89)

0 i' NRC.Form 366A U. UCLEAR REGULATORY COHHISS ION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92 I.ICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

'FACILITY NAHE (1) lDOCKET NUHBER (2) 8 I I I I sE()UENTIAL I I REVIsIDNI I I I I Drowns Ferry Uni t 3 I I I I I TEXT (If more space is required, use additional NRC Form 366A's) (.17)

C. D A xi f October 27, 1992 at 0028 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> CST Instrumentation personnel performing an SI placed U-3 reactor zone exhaust radiation monitor CH A in the trip test position per the SI which initiated a PCIS group 6 isolation.

October 27, 1992 at 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> CST LCO for TS 3.7.C. 2 was entered upon discovery of the damper failures.

October 27, 1992 at Seco'ndary containment was approximately 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> CST established and the LCO exited.

October 27, 1992 at 1750 hours0.0203 days <br />0.486 hours <br />0.00289 weeks <br />6.65875e-4 months <br /> CST A 4-hour report was made to the NRC as required by 10 CFR 50.72(b)(2)(iii)(C).

D. r ems or r F i n f None.

.E. h f Di vr:

The failures of the inboard and outboard dampers to close and the refuel zone supply fan to trip was discovered by the unit operator when he noticed both red and green indicating lights lit on control panel 3-9-25 for 3-FCO-64-42 damper. The operator then checked all other components for proper 'isolation and found 3-FCO-64-43 in the open position and the 38 refueling zone supply fan still'perating.

The Shift Operations Supervisor was notified and personnel were dispatched to physically verify positions of the inboard and outboard isolation dampers. LCO 3.7.C.2 was entered.

NRC Form 366(6-89)

0 NRC Form 366A U. UCLEAR, REGULATORY COMMISSION Approved OMB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) IDOCKET NUMBER (2) p I I I IsEQUENTIAL I IREVIsIoNI t I l t Browns ferry Unit 3 I Y I I I I tern TEXT (If more space is required, use additional NRC Form 366A's) (17)

G. f The reactor zone inboard, and outboard. dampers failed to close and the 3B refueling zone supply fan did not trip. All other safety components/systems operated as designed.

III. CAUSE OF THE EVENT d

The damper isolation failures were caused by two unrelated equipment malfunctions.

B. ~R ~iuse:

At this time, the root cause of the failed SOV is believed to be a defective valve stem. Further laboratory analysis by TVA and the vendor will be performed to better characterize the problem. The failure of the inboard damper to ful.ly close is bel.ieved to have been caused by debris stuck in the damper. This could not be fully verified.

IV. ANALYSIS OF THE EVENT This event occurred with units 1 and 3 defueled. No activities were in progress on these units that required secondary containment (i.e., no fuel handling activities in progress). Unit 2 was operating at power and required the secondary containment system to be intact as a secondary barrier to the primar'y containment barrier to prevent the uncontrolled release of radioactive material into the environment surrounding the pl'ant.

The inboard and outboard dampers are redundant to each other for secondary containment isolation purposes and the simultaneous failure resulted in secondary containment requirements not being met.

Technical Specificati'ons (TS) section 3.7.C.l requires secondary containment integrity be maintained in the reactor zone at all times except as specified in section 3.7.C.2. TS section. 3.7.C.2.b required the reactor zone secondary containment integrity to be restored within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or all reactors to be placed in a hot shutdown condition within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in a cold shutdown condition within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Secondary containment integrity was restored in less than 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> following the discovery of the 3-FCO-64-42 5 43 failures and LCO 3.7.C.2 was .exi ted.

NRC Form 366(6-89)'

41 ,i+[

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'NRC Form 366A U. CLEAR REGULATORY COHHISSION Approved OHB No. 3150-0104 (6-89) Exp i res" 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAHE (1)

I I I IsEQUENTIAL I IREVIsIBNI I I I I Browns Ferry Unit 3 I Y I I I I F

TEXT (If more space is required, use additiona1 NRC Form 366A's) (17)

Based on an inspection of the partially closed inboard damper position, it was calculated that the opening, size area was at most 480 square inches. Based on the last secondary containment test data and data taken for the standby gas treatment (SBGT) preoperational test with three trains of SBGT running, secondary containment could be maintained at a,l/4 i'nch of water with a ll00 square inch boundary breach. This exceeds the high side estimate of hole size of 480 inches square.

During this event, plant safety was not adversely affected and. the safety of plant personnel and the public was not compromised.

V. CORRECTIVE ACTIOt(S A. Imme i e rrec ive Acti n :

The refueling zone supply fan 3B 480V power supply breaker was opened to stop the fan. Reactor zone inboard and outboard isolation dampers were manually closed.

B. rre tive Acti n Preven R rren e:

1. TVA wil,l replace the secondary containment outboard damper solenoids.

2. The fai,led 3-FSV-64-43 solenoid will be examined at a TVA laboratory

.and by ASCO. A sample of solenoids removed as part of corrective action 1 above wi 1.1 also be examined.

3. The preventative maintenance (PH) activity on secondary containment dampers wi 11 be revised to include an, inspection for debri.s to reduce the risk of debris being caught in the dampers.

4. The radiation monitor calibration and functional test SI will be revised to require verification of damper positions.

VI. ADDITIONAL INFORHATION No additional equipment failed other than the components identified in section II.B.

NRC Form 366(6-89)

4l 4~

NRC. Form 366A U. CLEAR REGULATORY COHHISSION Approved OHB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAHE (1) (OOCKET NUHBER (2) N H I I I I sEQUENTIAL I IREVIsI0NI I I I I Browns Ferry Uni t 3 I I I I I TEXT (If more space is required, use additional NRC,Form 366A's) (17)

B. Pr v n i r v n TVA reviewed previous reported events to determine if similar past events had occurred. Based on this review there have been no LERs on a similar event. NPRDS, related industry events, and Browns Ferry maintenance history were also reviewed for similar occurrences. Numerous problems have been reported with solenoid valves (Ref. NUREG-1275 5 Generic Letter 91-15) .

Corrective action for generic concerns on solenoid operated valves is being addressed by TVA per Generic Letter 91-15 and NUREG-1275 which is currently under evaluation, VI I . COHHITHENTS

1. TVA will replace the secondary containment outboard damper solenoids by July 30, 1993.

2. TVA wi 1 1 examine the failed 3-FSV-64-43 solenoid at its laboratory. TVA will also have the vendor, ASCO, examine the solenoid to determine the cause of the fa'i lure. This corrective action wi 11 be completed= by July 30, 1993.

3. TVA will revise PH activity on secondary containment dampers to include an inspection for debris to reduce the risk of debris affecting damper operation by June 30, 1993.

4. TVA will'evise the radiation monitor calibration and functional test SI to require damper position verification by February 15, 1993.

Energy Industry Identification System (EIIS) codes are identified in the text as LXX3.

NRC .Form 366(6-89)

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