ML18153B060
| ML18153B060 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 09/02/1994 |
| From: | Saunders R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-94 94-521, NUDOCS 9409150039 | |
| Download: ML18153B060 (9) | |
Text
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SEP 02 '94 13:52 NLD e e
(
I VIRGINIA ELECT1uc AND PowB'.R CoMPA.NY RICHMOND, VIRGINlA 23261 September 2, 1994 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNIT 2 Serial No.
NL&P/MAE:
Docket Nos.
License Nos.94-521 RO 50-280 50-281 50-338 50-339 DPR-32 DPR*37 NPF*4 NPF-7 INITIAL NOJIBCATIQN OF DEFECT IN ACCORDANCE WITH 10 CfR 21 Virginia Electric and Power Company has identified a trend in the number of steam driven auxiliary feedwater pump overspeed trips during periodic tests. In accordance with 10 CFR 21.21, the following information is provided as initial notification of an existing defect. A written *report will be provided by September 30. 1994.
- 1. Name and address of the individual or individuals informing the Commission.
Mr. R. F. Saunders Vice President - Nuclear Operations Virginia Electric and Power Company 5000 Dominion Boulevard Glen Allen, Virginia 23260
- 2. Identification of the facility, the activity, or the basic component supplied for such facility or such activity within the United States which fails to comply or contains a defect.
Surry Power Station Units 1 and 2
~orth Anna Power Station Unit 2 Steam Driven Auxiliary Feedwater Pump Governor Valve
- 3. Identification of the firm constructing the facility or supplying the basic component which fails to comply or contains a defect.
9409150039 940902 PDR ADOCK 05000280 S
,SEP 02 '94 13:52 NLD
- Dresser-Rand Steam Turbines, Motors and Generator Division 37 Coats Street Wellsville, N.Y. 14895 Attn: Mr. A. M. Loughin Manager Navy Nuclear Product Engineering (716) 596*3343
- 4. Nature of the defect or failure to comply and the safety hazard which is created or could be created by such defect or failure to comply.
Virginia Electric and Power Company (Virginia Power) has implemented vendor recommended praciices provided in the technical manual and the Dresser Industries general information letter dated March 24, 1993 (attached).
This general information letter addressed corrosion related valve stem binding.
Although we have implemented the vendor recommended practices, VJrginia Power has identified a trend in the number of steam driven auxiliary feedwater pump overspeed trips during periodic tests. Since the trend was identified, the governor valve stems and carbon spacers have been replaced due to indications of corrosion related valve stem binding. Surry Unit 1 replacements occurred in December 1993 and May 1994.
Surry Unit 2 replacements occurred in January 1992, February 1994 and August 1994. North Anna Unit 2 replacements occurred in November 1993 and August 1994. North Anna Unit 1 has not recently replaced the governor valve stem and carbon spacers. Note that all of the Units with the exception of North Anna Unit 1 have experienced overspeed trips related to governor valve stem binding.
A Root Cause Evaluation is ongoing. Preliminary findings have identified the following:
- a. Corrosion and mineral deposits are accumulating faster than expected on the replacement governor valve stems. This accumulation may not allow the governor to move in the closed direction after the start of the turbine.
The turbine would then overspeed and trip rendering the auxiliary feedwater pump inoperable.
Based on metallurgical analysis the corrosion products are formed due to galvanic corrosion, crevice corrosion, and pitting corrosion. It has been identified that the graphite (carbon} spacers received from the Dresser*
Rand Steam Turbines, Motors and Generator Division have approximately 1.29% sulfur as a contaminant. Jt has not been determined what form the sutfur is in or if it has accelerated the corrosion process.
- b. Three differences have been identified between the original and replacement valve stem and carbon spacers:
Nitride thicknesses ( original 12* 14 mills, replacement 4-5 mills)
. SEP 02 '94 13:53 NLD
- P.4/10 Percent of contaminates in carbon spacers (original essentially pure carbon, replacement approximately 1.29%)
Flatness of the end of the stem that slides in the plug (original flat on bottom, replacement has a manufactured recess).
- 5. The date on which the information of such defect or failure to comply was obtained.
July 29, 1994
- 6. In the case of a basic component which contains a defect or fails to comply. the number and location of all such components in use at, supplied for, or being supplied for one or more facilities or activities subject to the regulation in this part.
There are three steam driven auxiliary feedwater pumps which are affected by this notification. At Surry, there is one in each of the Unit 1 and 2 Main Steam Valve Houses and at North Anna there is one located in the Unit 2 Steam Driven Auxiliary Feadwater Pump House.
- 7. The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be taken to complete the action.
The corrective actions to ensure operability are based on the type of corrosion, observed corrosion rate and design of the steam supply piping. At North Anna and Surry Power Station pitting corrosion has been observed in the stem packing area. Surry. is also experiencing corrosion build up near the gland seal leakoff area of the stem. In addition, the governor valve at Surry is the low point of the system, and the steam supply valves are approximately 4 feet from the governor valve. At North Anna the steam supply valve is greater than 100 feet from the governor valve. With the steam supply valve close to the governor valve, the ambient temperature of the governor valve is significantly warmer, which affects the corrosion rate.
Based on these factors. the corrective actions to ensure operability at each station are as follows:
Surry
- a. A maintenance procedure to stroke the governor valve stem is performed
- b. Monitoring of the corrosion build up in the gland seal leakoff area is performed weekly.
. SEP 02 '94 13:53 NLD
- e North Anna
- a. The periodic maintenance procedure to stroke the governor valve stem is performed monthly for North Anna Unit 2. This is followed by running the steam driven turbine.
Additional corrective actions, if necessary. will be based on the completion of the Root Cause Evaluation. This information will be transmitted to you in the required written report.
- 8. Any advice related to the defect or failure to comply about the facility, activity or basic component that has been, is being, or will be given to purchasers or licensees.
Virginia Power advises other licensees not to replace original equipment (stems. carbon rings, bushings and washers) until this issue is corrected~ If these components have been replaced, the licensees should consider 1) increased monitoring of initial turbine startup parameters and 2) replacement of the 410 nitrided stainless steel valve stem with a chrome plated valve stem as discussed in the general information letter from Dresser Industries dated March 24, 1993 (attached).
Should you have any questions or require additional information, please contact Mr.
M. L. Bowling, Manager Nuclear Licensing and Programs (804) 273-2699.
Very truly yours,
{ZJJ~
R. F. Saunders Vice President
- Nuclear Operations Attachment
. SEP 02 '94 13:54 NLD
- cc:
Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Mr. R. o. Mcwhorter NRC Senior Resident Inspector North Anna Power Station Mr. R. M. Loughin Manager Navy Nuclear Product Engineering Dresser-Rand Steam Turbines, Motors and Generator Division 37 Coats Street Wellsville, N. Y. 14895 P.6/10
P.2/5
.. ' *SEP 02 '94 14: 11 NLD *
~-------------------------------~----~--*
--DISPU Y OF RECORD 0489 Record l3st Revised: 05/12193
---~--~-------~--~--~----------~---~~----~----~------~~--~-~------~-------*
GENERAL lNFORMA TION lNITlAL REPORT DATE: 03/24/93 LA TEST REPORT DATE: 03/24/93 NRC ISSUE NUMBER:
0 REPORTING COMPANY:
DRESSER INDUSTRIES ACTIVI1Y:
PRIMARY COMPONENI': VALVE
- SUB COMPONENTS:
VALVE STEM PRIMARY MANUF.:
DRESSER INDUSTRIES SECONDARY MANUF.:
REFERENCES AFFECTED MODEL NUMBERS ZS GS AFFECTED PLANTS/UTIIJTlES UTILITIES:
NEQ90+5051-oo6 ENTERGY OPERATIONS DUQUPSNE LIGHT CO.
TENNESSEE VAU.EY AU1HORl1Y CAROLINA POWER & UGHT CO.
UNJON ELECTRIC CO.
BALTIMORE GAS & ELECI'RIC CO.
DUKE POWER CO.
IWNOIS POWER CO.
TEXAS UTllJTIES ELECilUC CO.
NEBRASKA PUBUC POWER DISTRICT FLORIDA POWER CORPORATION TOLEDO EDISON CO.
PACIFIC GAS & ELECTRIC CO.
AMERICAN ELECTRIC POWER SERV1C£ IOWA ELECilUC UGHT & POWER CO.
GEORGIA POWER CO.
DEiROIT EDISON co.
CONNEcncur YANKEE ATOMIC POWER co.
PUBUC SERVICE ELECTlUC & GA.S CO.
CONS0UDA1'ED EDISON OF NEW YORK NEW YORK PO'WER AU'IHORI1Y ALABAMA POWER COMPANY WISCONSIN PUBIJC SERVICE CORP.
COMMONWEAL1H mtSON COMPANY PHILADELPHIA ELECTRIC.CO.
MAINE YANKEE ATOMIC POWER CO.
NORTHEAST UilL111ES NIAGARA MOHAWK POWER CORP.
VIRGINIA POWER ARIZONA PUBUC SERVICE CO.
Cl.EVEL\\ND ELECI'lUC IU.UMJNATING CO.. BOSTON EDISON CO
- i
, *_sEP 02 '94 14: 11 NLD **
e WISCONSIN ELECTRIC POWER CO.
NORTHERN STATES POWER CO.
SACRA.MENTO MUNICIPAL unurr DISTRICT GULP ST.ATES ununE.S sournERN CALIFORNIA EDISON co.
NEW HAMPSHIRE YANKEE LONG ISLAND UGHTlNG CO.
HOUSTON UGHTING & POWER COMP.ANY FLORIDA POWER & UGHT CO.
PENNSYLVANIA POWER & UGHT CO.
PORTIAND GENERAL ELECTRIC CO.
VERMONT YANKEE NUCLEAR POWER CORP.
SOUTH CAROUNA ELECTRIC & GAS PLAl\\'TS:
ARKANSAS NUCl.EAR ONE BRUNSW1CK l BEA VER VALLEY BROWNS FERRY CAll.A WAY CALVERT CLIFFS CATAWBA 1 COOPER DIABLO CANYON HATCH HADDAM NECK FITZPATRICK LASALLE MCGUIRE NINE MILE POINT PEACH BOTTOM PQJr..'T BEACH RANCHO SECO
- SAN ONOFRE HARRIS ST. LUCIE TROJAN SUMMER WA1TS BAR CIJNTON COMANCHE PEAK CRYSTAL RIVER DA VI5,,BESSE COOK ARNOID FERMI 2 GRAND GoiF
. HOPE CREEK INDIAN POINT 2 FARI.EY KEWAUNEE LIMERICK MAJNE.YANKEE MILISrONE MON'TlCEilO NOR1H ANN.A PALO VERDE 1 PERRY PILGRIM PRAIRIE ISLAND:
QUAD~
RIVER BEND SAl.£M SEABROOK SEQUOYAH SHOREHAM soum TEXAS PROJECT SURRY
- SUSQUEHANNA 1tJRKEY POINT VERMONT YANKE£ VOGTLE WATERPO!m WNP ZION REPORT TEXT DATED MARCH 24, 1993:
REFERENCE:
TERRY 1YP£ GS AND ~
AUXJUARY FEED PUMP ORIVERS/RCIC GOVERNOR VALVE STEM GENTLEMEN:
'WE A lTACHED HERETO.,._ COPY OP A LEI I flt DATED MARCH 18. 1993 WHICH WAS SENT TO TH£ PLANTS USTED.
WE TRUST nL\\T THE ENCLOSED IS SELF EXP:lA.NATORY; HOWEVER, IF WE CAN BE OP fUR1HER ASSISTAN~ PLEASE DO NOT HESIT,ATE TO CONTAcr US.
BEST REGARDS.
CARLTON M. SLATER SERVICE ENGINEER
P.4/5
/,
- SEP l32 '94 14: 12 t'lLD
- I~. GEN11.EMEN:
ON All TERRY MODEL Z.S ANO GS TIJRBINES USING IBE 2 1/2" VEEPORT AND 3" VEITTURI GOVERNOR VALVES. 1HE VALVE STEMS ARE MADE OF NITRIDED 410 STAINLESS STEEL WITH CARBON RINGS FOR PACKING.
e TIIERE HAS BEEN A F£W NUCLEAR PLANTS EXHIBmNG CORROSION RELATED VALVE STEM BINDING. IT IS AGREED niAT VALVE STEMS OF nus CONSTRUcnON ARE SUSCEPnBLE TO CORROSIVE A1TACK DURING PROLONG£() EXPOSURE TO AN ENVIRONMENT OF STAGNANr OXYGENATED WATER.
THE DESIGN SEI.ECflON IS MADE WITH EXPECTAJ10N {BACKED UP BY VERY EXTENSIVE EXPERIENCE) 1RA T THE RESIDUAL CORROSION RESISTANCE OF NITRIDED 410 IS ADEQUATE IN A 1YPICAL STEAM TIJRBINE VALVE STEM ENVIRONMENT. 1HE FACT THERE ARE TiiOUSANDS OF STEAM roRBINES wtm NITRIDED 410 VALVE STEMS AROUND THE WORLD, INCLUDING MANY OF THEM IN STANDBY SERVICE PROVIDES A STRONG TESTIMONY TO TiiE EXPECI"ATION. ALSO* 1liERE ARE ONLY IDGHT OlIT OF J40 "NUCLEAR PLANTS ON OUR INSTALLATION UST WHICH HA VE REPORTED PROBI.£MS wrI1i CORROSION RELATED VALVE SIEM BINDINGS. TiiEREFORE, nns SUGGESTS STRONGLY TiiA TA REASONABLY NON-CORROSIVE V.AlVE STEM ENVIRONMENT IS BEING MAINTAINED BY THE OTiiER Pl.ANTS. 1llERE IS A S1MILARl1Y TO 11iESE TURBINES IN NUCLEAR PLANTS. nus SIMILARITY IS, 1HEY' AU. HA VE EXTENDED PBRIOOS OF IDLE STANDBY STATUS.
THE PUNTS nIAT ARE. HAVING THIS CORROSION ENVIRONMENT PROBLEM ARE NOT ADEQUATELY DRAINING nm UNIT AND/OR HAVE CORROSIVE WATER CHEMISTRY IN TiiE STEAM. TiiIS WATER IS 5rAGNATING IN 1HE VALVE STEM PACKING GLAND (I.-
GLAND). THE REAL SOLUTION IS TO HAVE ADEQUATE DRAINAGE AND ELIMINATE TiiE CORROSIVE ENVIRONMENT. HOWEVER, SOME OF TIIESE PLANTS HAVE CONCLUDED THAT THEY ARE UNABLE TO ASSURE A DRY AND NON-CORROSIVE CONTROL VALVE ENVIRONMENT.
ACCORDINGLY, THEY HAVE IDENTIFIED A NE£D FOR A VALVE STEM WJll-J HIGHER CORROSION RESISTANCE - SPECIFICALLY A STEM wmi CHROME PIA.TING APPIJED OVER A LA YER OF ELECTROI.:E.5S NICKEL ATI'ACHED JS A UST OF ntESE PLANTS AND 1HEIR EXPERIENCES..APTER READING THIS UST ONE CAN SEE iHAT 'THERE JS NO SELECI10N OP VALVE STEM MATERIALS WHICH, CAN BY ITSELF, PRELUDE TiiE POSSIBILI11" OF SURFACE DETERIORATION OR.ASSURE INDEFINIT£ FREEDOM FROM BINDING.
BECAUSE DRESSER-RAND HAS A HIGH REGARD FOR CUSTOMER SATISFACI10N, 1HERE IS A WIWNGNESS TO SUPPLY NUa.EAR GRADE CHROME PLATED VALVE STEMS TO THE PLANTS ntAT CAN NOT ASSURE.A DRY AND CORROSIVE PREE ENVIRONMENT AND ARE.
EXPERIENCING A CORR.OSIVE REI.AT£D BINDING PROBLEM.. 1liAT MEANS NOT All PLANTS FIT nus NEED ANJ? FOR niEM, NO CHANGE IS REQUIRED.
GOVERNOR VALVE STEMS DO NOT HA.VE A INFINITE LIFE SPAN. BASED ON DATA ON
'\\ THE NUMBER Of. THE 410 NITRATED VALVESTl!MS USED, nm AVERAGE SERVICE LIFE
P.S/5
- . SEP 02 '94 14= 13 t'lLD
. 1*
IS 5 PLUS YEARS. TiilS SUGGF.STS THAT THESE V AI.VE ST.EMS.ARE REPLACED ON A e
I PRfYENTATIVE BASIS AT NORMAL INSPECTION INTERVALS, NOT BECAUSE OF BINDING.
- (I ONLY VlGILANT ATrENTION TO GOOD OPERATING AND MAINTENANCE PRAcnCES CAN
" ASSURE A FREE AND OPERATION READY CON!'ROL VALVE. TiiESE PRAcnCES SHOUID
(
INCLUDE BUf NOT BE LIMITED TO; e
- 1)
CRITICAL ATTENTION TO 11iE CONTROL VALVE ENVIRONMENT. THIS INCLUDES STEAM CHEMISTRY AND ANY OTHER POTEN11AL SOURCES OF CORROSIVES AS WEU. AS SYSTEM ARRANGEMENTS AND PRACTICES TI!AT PROMOTE A WEll DRAINED CONTROL VALVE. I.E., DRY ENVIRONMENT FOR STEM AND PACKING ASSEMBLY, WHILE IN STANDBY STATIJS.
- 2)
PERIODIC INSPECflON OF 11iE VALVE STEM TO D:ET.ECT ANY SURFACE DETERIORATION TI!AT COULD LEAD TO BINDING AND/OR PERIODIC MONITORING OF THE FORCE REQUIRED TO MOVE nu; VALVE nmoUGHOur rrs STROKE RANGE.
TI-IE STEM SHOULD BE REPLACED IF EiniER SURFACS *DETERJORATION OR INCREASE IN REQUIRED S'lttOKING FORCE ARE FOUND TO BE SIGNIFICANr.
- 3)
CRITICAL ATI'EN'l10N TO ANY BINDING TENDENCIES 1HAT MAY BE EXHIBITED BY THE CONTROL VALVE DURING REGTJLAR SURVEIUANCE TBSTING.
HOWEVER, IF YOUR PLANT IS ONE 'IHAT CAN NOT ASSURE A DRY AND CORROSION FREE ENVIRONMENT, YOU CAN PURCHASE A NUCLEAR GRADE CHROME PLATED VALVE 5raM (SPECIFICALLY 410 STAlNI.ESS S'IEEL BAS£ MATERIAL WlTH CHROME PLATING APPLIED OVER A LAYER OF ELECI'ROLESS NICKEL) TO ACCOMMODATE 11iE ADOmONAL CORROSION RESISTANCE REQUIRED.
IF YOU HA VE ANY QUESTIONS REGARDING nm ABOVE OR WISH TO PURCHASE THE CHROME PU.TEO STEM, PLEAS£ CONTACT US. FOR QUF.STIONS CAll ED GRANDUSKY:
716-5~3631, TO PURCHASE PARTS CAU. MIKE LAUZZE: 716--596-3436 *.
BEST REGARDS.
CARLTON SLATER SERVICE ENGINEER
..