ML20043A284

Summary of 900509 Meeting W/Util at Site Re Problems W/ Valves in Auxiliary Feedwater & Main Feedwater Sys.List of Attendees & Viewgraphs Encl

ML20043A284
Person / Time
Site:	Comanche Peak
Issue date:	05/16/1990
From:	Joshua Wilson Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9005210150
Download: ML20043A284 (23)

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May 16, 1990

' Docket No. 50-445 LICENSEE:

Texas Utilities Electric Company (TV Electric)

FACILITY:'

Comanche Peak Steam-Electric Station (CPSES), Unit 1

SUMMARY

OF MEETING ON MAY 9. 1990 TO DISCUSS PROBLEMS WITH VALVES IN THE AUXILIARY FEEDWATER.

AND MAIN FEEDWATER SYSTEMS' t

I On Ma'y-9,1990, the staff met with. representatives;of TV Electric at the.

I Comanche Peak site to discuss recent operational-problems with leaking-4" Borg-Warner swing arm check valves in the auxiliary feedwater (AFW) system discharge piping and with main feedwater system isolation valves that. fail to open due'to thermal binding of the valve Internals.A list 1of attendees-at the meeting is, provided as Enclosure 1.

The slides used in TU Electric's presentation are provided as Enclosure 2.

With respect to the AFW valves that leak by resulting. in elevated temperatures:

in the AFW^ system discharge piping, the licensee stated that, in' the short terrt, t

it intends to perform upstream venting of the check valves in. order to facilitate more positive ~ seating of the valves.: (These check valves tend to-unseat slightly underl low differential: pressure conditions Lallowing the leakage.

Venting of the upstream piping)provides greater. differential pressure and hence, greater closing _fnrces.

The licensee indicated that the evaluation of o'

l the leaking check valve problem would be complete by May 25, 1990.

The evaluation report will contain recommendations for a long-term solution for the leaking-L check valves.

Possible long-term solutions include modification of the existing check valves, replacement of five' existing check valves with'another design, or i

modification of the existing auxiliary feedwater system configuration' for standby service.. Licensee management indicated that it would inforn NRC of. its long-term dCtions prior to Completing its 50% power' plateau self-assessment.

'4 The licensee also discussed the use of hydraulic lifting devices to facilitate-the opening of the main feedwater system isolation valves.

The 'NRC staff raised the concern that the use of such devices.may result in damage to the valves.

t because of possible excessive lifting forces. TV Electric stated that it performed an analysis that demonstrated that the use of hydraulic lifting devices was acceptable for long-term use.

The licensee indicated that it intended p

to use the hydraulic lifting cevices during the short term'while it was evaluating long-term options.

1 Because there has been some leakage-through the feedwater preheater bypass valves (FWPBVs) which has contributed to operational problems associated with the leaking AFW check valves, the staff questioned their operability.

The licensee 4

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Summary of May 9,1990 Meeting j

stated that the leakage past the FWPBVs 'did not affect' their operability because Lthere are no leakage criteria in the plant technical specifications associated-1 a

1 with the valves, and they can be isolated with a manual bypas. v lve.

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Jaiw H. Wilson, Assistant Director.:

fo Projects'

. Comanche Peak Project Division.'

' Office of Nuclear Reactor Regulatien-i

Enclosure:

.1. - ' List of Attendees 2.

. TU Electric's Presentation Slides-l 5

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Assistant' Director Jack R. Newman,-Esq.

for Inspection. Programs-Newmen & Holtzinger 1615 L Street, NW Comanche Peak Project Division

. Suite 1000 R

U. S. Nuclear Regulatory CommissionL 1

P. O. Box 1029 Washington, D.C.

20036

' Granbury Texas 76048-Chief, Texas Bureau of. Radiation' Control-Regional Administrator. Region ~lV.

Texas Department -of Health U. S. Nuclear' Regulatory Commission 1100 West 49th Street 611 Ryan Plaza Drive, Suite 1000 Austin, Texas 78756 Arlington, Texas 76011.

Honorable George Crump

'Ms. Billie Pirner Garde, Esq.

County Judge :

Robinson,-Robinson, et al.

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Glen Rose, Texas 76043 103 East College Avenue Appleton, Wisconsin 54911 Mrs. Juanita Ellis, President Citizens Association for Sound Energy 1426 South. Polk Dallas, Texas 75224 E.-F. Ottney-P. O. Box 1777 Glen Rose Texas 76043 Mr. Roger D. Walker Managerj Nuclear Licensing Texas' Utilities Electric Company 400 North-Olive Street, L. B. 81 1

Dallas, Texas -75201 Texas Utilities Electric Company c/o Bethesda Licensing 3 Metro Center, Suite 610 1

Bethesda, Maryland 20814 William A. Burchette, Esq.

Counsel for Tex-La Electric Cooperative of Texas heron, Burchette, Ruckert & Rothwell i

1025 Thomas Jefferson Etreet, NW Washington, D.C. 20007 GDS ASSOCIATES, INC.

Suite 720 1850 Parkway Place Marietta, Georgia 30067-8237 o

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-NRC/TV ELECTRIC MEETING AT COMANCHE PEAK SITE CONCERNING OPERATIONAL PROBLEMS WITH:THE MAIN'FEEDWATER' AND AUXILIARY FEEDWATER SYSTEMS:

May 9,?1990

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TU' Electric CASE j

<P.:Gwynn.

.W..Cahill'

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J.:Jaudon

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'J. Wilson J. Beck.

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D.ichamber. lain C. Hogg-

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M..Blevins:

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K.-Tipton S.> Bitter I.,Whitt

' D. <. Graves D. Reimer

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J. Donahue Si Palmer-J. Boatwright.

B.. Rice 1T.1Jenkins.

K. Bishop' T. Heatherly '

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ELEVATED AFW PIPING TEMPERATURES o

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. INTRODUCTION'AND: OVERVIEW MIKE BLEVINS:

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0 EVALUATIONoTEAM REPORT KEN TIPTON u

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[EEDWATER; ISOLATION 4 VALVE' IVAN WHITT UPENING "l

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SUM 4ARY. & - QUESTIONS JIM'KELLEY j

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OVERVIEW -

l ElevatodiAuxiliary Feedwater piping:

Ltemperatures observed.during plant-startup.

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Responded ~ promptly_ with' technical and:

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msnagement. assistance.--

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!1 Evaluated -situations and!took corrective action.

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.Different problem' than 1989:HFT l;

Check valves were not-hung lopen.

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No operator errors involved with the event.-

L Reverse flow was.not from steam generators.

. Conclusions to-date v

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Current Plant Status I

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AUXILIARY.:-FEEDWATER FLOW PATH ERx L

power I.Es's THAN 3%

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TRANSITION' FLOW PATH o

MAIN FEEDWATER FLOW-PATH.-

Rx: POWER GREATER'THAN 30%

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o TIME LINE 4/24/90 1642 Operator observes AF line temperatures increasing with Feedwater temperature as indicated on main control board i

temperature indicators. Check velve back leakage suspected.

1645 Actions per abnormal condition procedure (ABN) initiated 1

2000 Technical team formed to evaluate operability, initiate required preliminary corrective actions.

2200 Piping temperatures in pump rooms 165 F.

4/25/90 0100 ONE Form initiated to document the AFW check valve L

back leakage and determine operability.

l 0251 Check valves ressated per ABN procedure.

. No valves hung open f

e Leak rates quantified e Valves will nerform required safety function e No temperature effects on piping e Operability not affected 0755 Temperatures increasing again. Operations suspects check valve back-leakage and Initlates actions per ABN 0800 Evaluation team established to investigate / evaluate AF elevated line temperatures l

1600 Management meeting to discuss status of evaluation team 4/26/90 0400 Performance and Test personnel verify check valve back leakage rates.

0800 Management meeting to discuss shon term action options.

1600 Management meeting to discuss short term corrective actions e Controlled periodic venting of upstream AF piping.

i 1700 Technical Evaluation to provide guidance on venting,

TIME LIFE l

4/27/90 Procedure change to Operations procedure to provide for

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controlled periodic manual venting.

FWlV's opened. FWPSV's closed.

4/28/90 2 of 4 Feedwater Preheater Bypass valves leaking by Procedure change to Operations procedure to provide for isolating Feedwater Preheat Bypass valves above 30%-

reactor power through-use of upstream manual isolation valve. Valves not leo lated at this time.

Manually trisped Main Turbine to repair leaking pressure transmitter. NIV's closed, FWBV's opened.

4/29/90 Main Generator back on grid.

Opened FWlV's, FWPBV's closed /not isolated.

4/30/90 AF line temperatures increasing.

Actions initiated per ABN procedure.

Temperatures stillincreasing.

Actions re-Initiated per ABN. AF line temp reaches 235 degrees.

Check valve ressated per ABN. Line temperatures decreasing.

U stream line pressure drops below 50 psi limit to 25 psi

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( ST pressure) 5/1/90 Feedwater Probeater Bypass valves manually isolated.

Auxillary Feedwater system In normal-standby operation, piping at ambient temperature.

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FEEDWATER PREHEATER BYPASS VALVES CORRECTIVE ACTION o

THE MANUAL ISOLATION VALVES WERE CLOSED AFTER THE WATER HAMMER INTERLOCK WAS CLEARED-AND FLOW THROUGH-MAIN FEEDWATER ISOLATION VALVE ESTABLISHED.

ISOLATINGFPBVMANUALLYWILLMAINbAIN O

AFW PIPING TEMPERATURES'BELOW 210 F WITHOUT OPERATOR ACTION.

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AT THE NEXT MAINTENANCE OUTAGE THE VALVES EDENTIFIED AS LEAKING WILL BE REPAIRED.

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EVALUATION TEAM CORRECTIVE ACTIONS UNDER CONSIDERATION SHORT TERM o

CONTROLLED PERIODIC VENTING LONG TERM o

MODIFY EXISTING CHECK VALVES TO PROVIDE MORE POSITIVE SEATING O

REWORK FEEDWATER PREHEATER BYPASS VALVES DURING A MAINTENANCE OUTAGE O

MODIFY AUXILIARY FEEDWATER SYSTEM CONFIGURATION FOR STANDBY SERVICE o

REPLACE EXISTING OHECK VALVES WITH ANOTHER. DESIGN o

PROVIDE TEMPERING FLOW FROM AFW THROUGH FEEDWATER-TRANSITION c

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i FEEDIdA"ER ISOLATION VALVES 1

DES: :GN BASIS SUMARY o

REautaED TO. ISOLATE CONTAINMENT.

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REcu! RED TO ISOLATE FEEDWATER TO i

MINIMIZE MASS-AND ENERGY RELEASE INSIDE CONTAINMENT DURING A LINE BREAK q

l EVENT AND MINIMIZE RCS c00LDOWN..

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FEEDWATER ISOLATION-VALVES:

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-Operations tried to open the Feedwater Isolation Valve with the handswitches in the Control Room.

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o Problem determined to be mechanical binding due to I

thermal growth of valve L

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t" FEEDWATER ISOLATION VALVES CORRfCTIVE ACTI0ii a

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'A\\ HYDRAULIC + LIFTING DEVICE WILL BE USED TO ASSISTEOPENING OF',THE:

FEEDWATER ISOLATION VALVES.

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STILL EVALUATING LONG-TERM CORRECTIVE-ACTIONS.

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Summary of May 9,1990 Heeting stated that the leakage past the FWPBVs did not affect their operat'ility because thtre are no leakage criteria in the plant technical specifications associated with the valves, and they can be isolated with a manual bypass valve.

(original signed by)

James H. Wilson, Assistant Director for Projects Comanche Peak Project Division Office of Nuclear Reactor Regulation

Enclosure:

1.

List of Attendees 2.

TV Electric's Presentation Slides cc:

See next page 31 TRLBUTION i:2l

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