ML18044A680
| ML18044A680 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8003280484 | |
| Download: ML18044A680 (13) | |
Text
Docket No. 50-255 Mr. David P. Hoffman Nuclear Licensing Administrator Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201
Dear Mr. Hoffman:
JC)r'*t**
A.JI.)
On December 28, 1979 the NRC Office of Inspection and Enforcement issued Information Notice No. 79-37 that presented information available to the staff related to the discovery of cracks in the keyway and bore sections of Hestinghouse 1800 rpni lm*J pressure turbines.
,; copy of this Information Notice 1;Jith errata sheet is enclosed.
~iestinghouse notified utility users of this potential problem on October 30, 1979 and was requested by the staff to present a similar briefing in Bethesda, MaryJand en December 17, 1979.
You were contacted on December 14~
1979 and invited to send representatives to the staff briefing and alsci were requested to advise the staff of the actions being taken "in regard to this potentia1 problem at your operating nuclear power plant.
Westinghouse was Jater requested to meet aguin i*iith the staff and 1icensee-users on,January 8, 1980 to supplement the *information provided in the earlier meeting and in i ntcrirn correspondence \\'lith the staff.
On the basis cf information provided by HestinghousE: and recent indications from turbine disc inspections now undel":wy at Arkansas Nuclear One Unit.
1, Beaver Va11ey Unit 1 and Indian Point Unit 2, it is evident that the probability of cri."lck formation in these turbine discs is significantl.Y greater than previously assumed by the vendor.
l3y 1 etter of December 28, 1979, you notified the staff that ke,ywa,y cracks had been found in LP turbines J\\ and B at Palisades.
In your letter and, again, at a meeting with the staff on January 18, 1980, you advised the staff that analyses of the discs cracks indicated that the turbines could be operated safely unt i1 they were inspected again in 9 to 12 months.
~Je request that you update the information provide.ct in your December 28, 1979 letter and also, within 20 days of the date of this letter, provide and analyze the safety significance of the information requested in Enclosure 2 to this letter.
OFFICE*;*...................................
SURNAME~-...................................
DATE~........*....................... *...
NRC FORM 318 (9-76) NRCM 0240
"-tru.s. GOVERNMENT PRINTING OFFICE: 1979-289-369
Mr. David Because of the general nature of *the information sought in Enclosure 2 we are transmitting a copy of this enclosure to Westinghouse
- by separate letter.
As discussed in the December 17, 1979 meeting we urge you to address the gener"ic aspects of this problem and. to coordinate your responses through an owner's group.
Enc.losures:
- 1.
IE Inform~tion Notice No. 79-37
\\.Sith Errata Sheet Sincerely, OR=cT---.,":"' ~---,..,----:_:~BY Di1.Q:;_i.-2~~ u. ~~~~~1*~"!-IU*T -
Darrell G. Eisenhut, Acting Director Division of Operating Reactors
- 2. *Request for Information Related to Turbine Disc Cracks - 20 Day Response cc: w/enclosures See next page w~,J~ihD SEE PREVIOUS YELLOW FOR DISTR B OFFICE~P~fl>'P~R....... *................
SURNAME~.D~hU.t......................
DATE~-~~.Q.......................
NRC FOR_M 318 (9-76) NRCM 0240.
- u.s. GOVE~NMENT PRINTING OFFICE: 1979~289-369 __ 8__fl__1'* 3 2 8 O'f ~'{-
Mr. David Likewise, you are requested to provide and address the safety significance of the information in Enclosure 3 with'ln 60 days of the elate of this 1 etter.
Because of the general nature of tile information sought in Enclosures 2 and 3 we are transmitting a copy of these enclosures to l*Iest*inghouse by separate letter. As discussed in the December l7s 1979 meeting we urge you to address the generic aspects of this problem and to coord*i nate your responses through an owner's group.
Sincerely, Darrell G. Eisenhut, Acting Director Division of Operating Reactors
Enclosures:
- 1.
IE Information Notice No. 79.37 Hith Errata Sheet
- 2.
Request for Information Related to Turbine Disc Cracks - 20 Day Response
- 3. Request for Information R~lated to Turbine Disc Cracks - 60 Day Response cc: w/encl osur1::s See next page DISTRIBUTION Qi)_s:~
NRC PDR Local PDR ORB #2 Reading NRR Reading DLZiemann HSmith RDSilver WRoss OELD OI&E (3)
. DCru tchfi e 1 d O_FFICE~.~2 suRNAME~.RDS.'. ve.r.:a.h..
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NRC FORM 318 (9-76) NRCM 0240
((u.s. GOVERNMENT PRINTING OFFICE: 1979-289-369
- ~r. David P. Hoffman cc w/.enclosures:
M.*1. Miller, Esquire Isham, Lincoln & Beale Suite 4200 One First Nati anal Plaza Chicago, Illinois 60670 Mr. Paul A. Perry, Secretary Consumers Power Company 212 West Michigan Avenue
- Jackso~, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Company 212 West Michigan Avenue Jackson, M~chi;:~ 492C1
- .~yron M. Cherry*, Esquire Suite 4501 One IBM P l az a Chicago, Illinois 606il Ms. Mary P. Sinclair Great Lakes Energy Alliance 5711 Summerset Drive Midland, Michigan 48640 Kalamazoo Public Library 315 South Rose Street
- Ka1a~azoo, Michigan 49006 iownshi p Supervisor Cove rt Township Route 1, Box 10 Van Buren County, Michigan 49043 Office of the Governor (2)
Room l - Capitol Building Lansing, Michigan 48913 Director, Technical As~essment Ji vision Df7ice cf Radiation Programs r***
~C:O)
\\Mr*i-..,.....;
J. S. ~nvironmental Protection
.:...g-en:,y
- rys:al ~~all #2
~rli~stcn, Virgini*a 20460 3 -
February 25, 1980 U.
S~ Environmental Protection Agency Federal Activities Branch Region V Office ATTN:
EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Charles.Bechhoefer, Esq., Chainnan Atomic Safety and Licensing Board Pane.1
- U. S_. Nu cl ear Regulatory Corrmi ssi on Washington, D. C.
- 20555 Or. George C. Anderson Department of Oceanography University of Washi.ngton Seattle, Washington 98195 Or *. M. St.anl ey Li vi ngston 1005 Calle Largo Santa Fe, New Mexico 87501 Reside~ Inspector c/o U. S. NRC P. O. Box 87.
South Haven, Michi~an 49090 Palisades Plant ATIN:
Mr. J. G. Lewis Plant Manager Covert, Michigan 49043
- UNITED STATES HUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 28, 1979 c.1~ 1u:.urc: 1 e
ISINS NO.:
6870 Ac:c:ession No.:
7910250525 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS Description of Circumstances:
An anonymous letter was received by the Director-of the Office of Inspection and Enforcement, on November 17, 1979 which alleged possible violation of Part 10 CFR 50.SSe and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Westinghouse 1800 rpm low pres~ure turbine discs.
Westinghouse had ~ade a presentation on the turbine disc cracking to electric utility. executives on October 30, 1979.
lelephone*d1scussions betwreen theNRC staff and we*stinghouse'$*Turbine Division*
on Nover:.tler 20, 1979 established that cracking, attributed to stress corrosion pheno~ena, had been found in the keyway areas of several LP t~rbine discs at operating plants and that inservice inspection techniques (i.e., in situ ultra-sonic e~adination) for crack detection have been developed anc are being imple-mented in the field.
The Office of Inspection and Enforcement ~as also notified on Nover.:!::ler 20, 1979 that during the current overhau-1 of Cou.:.rnc:::i,..*ealth Edison's Zion Unit 1 LP turbine, ultrasonic examination revealed embed~=~ cracks located on the inlet side on the disc bore area where no cracks had been previously observed.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than ths keyway cracks found to date.
According to We~tin~house, these.
. bore cracks have been metallurgically examined and preliminary findings show them
- not to be typical of classical.stress.corrosion cracking observed in the keyways.
The probable cracking mechanism and impact on disc integrity is bei.ng further evaluated by '..'estinghouse.
A mee:ing. was.held on Decei.iber 17, 1979 between the NRC staff, Westinghouse and ~:ili:y re;::resentatives to discuss the disc cracking prcb~err., repair alter-natives, ":.u:""bine ::issile eva:uation, inspection tec:iniques anC: plant inspection priorities.
In response to the staffs' request, Westinghouse ;:>roviC::ed the staff ar. t.:pcated re;:iort en Decewber 21, 1979 regarding the current field inspection progr~~ that ir.cluded a list of nuclear power plants already ins~ected, recom-meri::::;:: inspection schecui es and perti n:nt information re 1 ated to LP turbines where cracks have been o~served.
Inspections to date have id~ntified turbine disc crac~s at Surry Unit 2, Point Beach Unit 2, Palisades, lr.dian Point Unit 3 and Zion Unit 1.
A11 units except Point Beach Uriit 2 will make repairs before.
the plants return to power.
Point Beach returned to power on December 23, 1979 with a srnall crack in the Ho. 2 disc of LP Turbine No. 2.
An analysis by WestiMghouse indicated that the observed crack will not attain critical dimensions during 28 additional conths of turbine operation.
The NRC staff is evaluating the turbine inspection results and analysis by Westinghouse.
- December 28, 1979
- Page 2 Df 2 Westinghouse also notified the staff that extrapolation of information ob~ained from Indian Point Unit 3 ins~~ction and analysis indicates that disc cracking could be significant at Indian Point Unit 2 and the turbines should be ins?ected sooner than the spring outage of 1980.
The NRC staff is currently reviewing Consolidated Edison's plans for prompt evaluation of this potential problem at this unit.
Enclosure l lists the Ph~ plants having Westinghouse 1500/1800 rpm turbines.
The AA category represents those turbines which appear to have the earliest need for inspection.
With the exception of Yankee Rowe, Westinghouse has recol!r.'lended to utilities that inspection of these machines be completed by the Spring 1980 outage period.
The Rowe unit is *uninspectable by the present ultrasonic techniques due to its design.
Westinghouse has recommended the reliiaini ng machines of the Category A pl ants be inspected as their service periods approach five years or in the event significant corrosion problems become evident during this time.
The NRC staff is currently reviewing the need for inspe:ti.on of those PWR plants having other tnterfac*ing turbine designs shown*
i*n En:l osure 2.
Changes to the f orement i oned inspection sche*dul es proposed by
\\.i'est~:ighcuse may be necessary as new technical inforr::ation becomes avai1atile.
Frc~ ~he information available to the NRC *staff at this time it appears t~at crc:6~fl"l'g may be more generically widespread in turbir.e discs (e.g., key*wa}s and bore areas) than previously observed.
It is important to note that the UT inspe:tions performed by Westinghouse thus far were essentially 1i~ited to the key*.... ays (disc outlet) of selected discs whereas the Zion. Unit 1 inspe:tion results indicate that examination of the disc bore section must be taken into account.
A1so, Westinghouse is currently re-evaluating their previously estimated turbine missile energies based on recent missile test results from model syr.-.metric and non-symmetric missile *impact tests.
Their preliminary findings, although subje:t to change, now indicate possible higher missile exit energies in some cases th~n previously expected.
This :nforrnation Notice is provided as an early notification of a possibly si;:-.~7icant matter, the allegations and the generic safety implications o7 -..*hich a;e c;.:rre:i:.ly undergoing review by the NRC staff. It is expected that re:ipients will review the information applicable to their facilities.
If NRC evalu~tions so ir.:icate, further licensee actions may be requested or required.
Ec~e:ded cra:kfog in keyways -and disc bore areas have been observed only in 'riest i n;house LP t~:-bines thus far.
However, the NRC staff believes that turbines of o:her manufacturers should be included in consideration of this problem.
. No written response to this Information Notice is required.
If you have any questions regarding this matter, please contact the Director of the appro~riate NRC Regional Office.
Enclosures:
As stated
e e
CATEGORT AA UTILITY STATION UNIT Florida, P&L Turkey Print 3
Consolidated ED.
Indian Plint 2
PASNY Indian Paint
~.
3 Arkansas P&L Russe11ville l
VEPCO Surry l
Carolina P&L Robinson 2
So. Calif. Ed.
San Onofre 1
Yankee A. P.
Rowe 1
Wisc. Mi ch. Pwr.
Point Beach l
Consumers Pwr.
Palisades 1
Commonwea 1th Ed.
- Zion l 1
Commonwealth Ed.
Zion 2
- 2 Florida P&L
. Turkey Poin_t 4
Nebraska PPD Cooper l
Wisc. Mich. Pwr.
Point Beach 2
Maine Yankee Bai 1 ey Point 1
Rochester G&E Ginna l
Northern States Prairie ls 1 and 1
Wisc. P.S.
Kewaunee 1
~. -----. - - *--
- e Enclosure l (Continued)
Page 2 of 3
- lJTILITY Alabama Power Alabama Power Baltimore G&L Carolina P&l Carolina P&L Carolina P&l Carolina P&L Ci nci nnat i G&E Com.11onwea l th Ed. **
Corr1:11on.,.,*ea 1th Ed.
Col"l'rilonwea l th Ed.
Corrmonwea.l th Ed.
Connecticut Yankee Duke Power Duke Power Duquesne Lt.
Duquesne Lt.
Duquesne Lt.
Flordia Power Corp.
Flordia P*ower &
Flordia Power &
Hous-:on L&P Houston L&P Louisiana P&L Metropolitan Ed.
Lt.
Lt.
Northern States Pwr.
Pub. Service E&G.
Pub. Service E&G Pacific G&E Pacific G&E CATEGORY A STATION Farley Farley Calvert Cliffs Harris Harris Harris Harris Zimmer Byron
.* Byro.n
- Braidwood Braidwood Haddam *Neck McGuire McGuire Shippingport Beaver Valley Beaver Valley Crystal River St. Lucie*
St. Luci*e So. Texas So. Texas Waterford Three Mile Island Prairie Island Salem Salem Diablo Canyon Diablo Canyon UNIT l z z
1 2
3-4 1
l
- 2 1
2 l*
l 2
- 1.
l 2
3 1
2 1
2 3
2 2
1 2
1 2
e e (Continued)
Page 3 o_f 3 I
CATEGORY A UTILITY STATION UNIT
- p. s. Indiana Marble Hill 1
P.S. Indiana Marble Hill 2
. Puget Sound P&L Skagit 1
SMUD.
Rancho Seco 1
TVA Sequoyah 1
TVA Sequoyah 2
TVA Watts Bar 1
TVA Watts Bar 2
VEPCO North Anna 1
Nor.th Anna 2
VEPCO North Anna 3
VEPCO North Anna 4
VEPCO North Anna 2
'r.'PPSS Hanford 2
Y.'PPSS WNPS 1
',,'PPSS WNPS 3
""PPSS WNPS 4
WPP SS WNPS 5
-~--------------~
UTILITY STATION UNIT Duke Power Co.
Oconee 1
Duke Power Co.
Oconee 2
- )
Duke Power Co.
Oconee 3
OPPD Ft. Calhoun 1
Baltimore Electric
& Gas Calvert Cliffs 1
Metropolitan Edison Three Mile Island 1
Indiana & Michigan Electric D. C. Cook 1
Indiana & Michigan Electric D. C. Cook 2
Northeast Utilities Mi 11 stone 2
Portland General Electric Trojan 1
Toledo Edison Davis Besse 1
Arkansas Power &
Light Arkansas Nuclear One 2
WPP SS Hanford l
Errata Sheet For IE Infon;~tion Notice No. 79-37 Page 1, paragraph 2, line 9:
Change "inlet" to "outlet" Page 1, paragraph 3, 1 ines 9 and l 0:
Change "Point Bech Unit 2 11 to*
"Point Beach Unit 1 11 Page 1, paragraph 3, line 10: After Point Beach.Unit 1 add ar. asterisk
(
11.*
11
) footnote and place a note at the bottom of the page as follows:
"*Wisconsin Electric Power Company orally notified the NRC proje:t manager on November 5 that turbine disc cracking had been observed at Point Beach Unit 1.", line 4:
Change "Russellville" to "ANO", line 8:
Change to read:
"Yankee Atomic ~lectric, Yankee.Rowe", 1 ines 9 and 15:.Change "Wisc Mich Pwr" to "Wisc El ec Pwr" Enclos.ure 1, line 16:
Change to read 11Maine Yankee Atomic Pwr, Mc.ir:e Yankee", page 3, line 13:
Delete as redundant reference to Nc~th Anna 2 REQUEST FOR INFORMATIO:l RELATED TO TU?..BirE DISCS SITE S?ECIFIC GEN~RAL QUESTIONS - To BE Sompleted in 20 Days
- l.
Provide the following information for each LP t~rbine:
A.
- Turbine type B.
Number of hours of operation for each LP turbine at time of last turbine inspection or if not inspected, postulated to turbine inspection C.
Number of turbine trips and overspeeds D.
For each disc:
- 1.
type of material including material specifications
- 2.
tensile pr6perties data
- 3.
toughness properties data including Fracture Appearance Transition Temperature and upper energy and temperature
- 4.
keyway temperatures
- 5.
calculated keyway craci< size for turbine ti;:;e specified in 118 11 above
- 6.
critical crack size
- 7.
ratio of calculated crac~ to critical.crack size
- 8.
crack. growth rate
- 9.
calculated bore and keyv;ay stress at op::rating design overspec:d
- 10.
calculated K1c data
- 11.
~ininu~ yield strength s;ecifie~ for ea:h disc II.
Pro\\!ide details of the results of any cor::;:ileted inse:vice ins;:iection of LP turbine rotors, including areas examine~, since iss~a~ce cf an operating license.
For each indication oe~ected, proviae det~i~s of :he location cf the crack, its orientation, an~ size.
III. ?rovide the nominal water che~is:ry ccn~itions for each LP turbine and describe any condenser inlea~ages or other si;~ificant changes in seconda:y water chemistry tc this poi~t in its operating 1ife.
J~sc~ss the occurrence of cracks in any given turbine as related to ~istory cf se:ondary water che~is:ry in the unit.
IV.
~;your plant has not been ir.s;:;:c:ec, des:ribe y:*ur :rc:J:se: sche:Juie and ap~roach to ensure that turbine cracking does n~t exist i~ yJur ~urbine.
V.
ffyour ~lant has been inspected and plans to re:urn or has returnee to power with c~acks, provide your proposed schedJle for the next tJrbine inspection and the basis for this inspection schedule.
VI~
Indicate whether an analysis and evaluation regarding turbine missiles have been performed for your plant and provided to tne s:aff. If such an analysis and evaluation has been perfor~e: and reported, please provide a~propriate references to the available docu~entation. In :he even: that su:h studies have not been made, consider~tion should be given tc schetJling such an actic~.
e e --
GE~JERIC QUESTIONS - To Be_ ":.Jmpleted in 20 Days I.
Describe what quality control and inspection proce:ures are used for the disc bore and keyway areas.
II.
Provide details of the Westinghouse repair/replacenent procedures for the faulty discs.
III. What iimiediate and long term actions are being tak:n by Westinghouse to minimize future stress c.orrosi on prob1 ems with turbine discs?
What actions are being recomended to utilities to 1:1ininize s*tress corrosion cracking of discs?
rv.
Identify the impurities known to cause cracking in the low pressure turbines, and their sourc~s. Discuss the relationship between steam generator chemi.stry and steam *chemistry relative t: t.h~ introduction of corrosive impurities into the turbine, incluc:in; phosphate, AVi, ZSi, and Bl.'R chemistry. Discuss the mechanisrr. of :eposition of these impurities that can lead to their concentraticn ir. certain areas of keyways, and bores.
V.
What role does the refluxing action in the stea= S!?aratio~ portion of the steam generator have on scrubbing corrosive i:n::~~itie~ frOCI the steam?
\\'I.
io what extent can the buildup of corrosive i~~ri:ies in the LP turbine be alleviated? What would be the effects ~f the following actions:
yn...
- 1. Pumping moisture separator condensate to co~d:~ser?
- 2. Periodically moving point of conder.sation t: ~-event localizec buildup of corrosive impurities?
Describe fabrication and heat treat"'lent sequer.:: f~r discs, includin:
thermal exposure during shrinking operation~.
VI I I. Discuss the effects of any local residua 1 stresses on the er acid ng mechanism.