ML18138A073
| ML18138A073 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Ferguson J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 8003140436 | |
| Download: ML18138A073 (16) | |
Text
...,.
FEBRUARY 2 5 1980 j)ocrc,
(/LE
&~80 Docket Nos. 50-280 a n<l 50-231 rr. J. H. Ferauson Executive Vice President Pov:er Vir~1inia Electric and Power Company Post Office Box 26666 Richmond, Virginia 2~261 Dea\\" Mr., Ferguson:
On D2cember 28, 1979 the MRC Office of Inspection and Enforcement issued
' Inforn@tion Notice No. 79-37 that oresentad information available to the staff related to the discover/of cracks. in the keyviay and bore sections of Westinghouse 1800 rpm lov1 pressure turbines.
fl. copy of this Information Notice v1ith errata sheet is enclosed.
Westin9house notified utility users of this potential problem on Octob~r 30, 1979.and \\Jas requested by the staff to present a *similar briefing in
- t:',ethesda, Maryland on December 17, 1979 *. You 1;1ere contacted en December M, 1979 and invited to send rcipresentatives to the staff briefing and also were requested to advise th~ staff of the actions_ being taken in regard to this potential rroblem at -your operating nuclear power plant.
\\*iestinghouse \\vas later requested to meet a.gain 1;1ith *the stafr and licensee-users on January 8, 1980 to supplement the information provided in the earlier r;*:eeting crnd in interim correspondence with the stc.1ff.
On the bas*is of.inforrnation provi_ded by t*./estinghouse and recent *indications from turbine disc inspections nm*1 unden.iay at l\\rkansas Nuclear One Unit 1, G_eaver Va11ey Unit 1 and Indian Point Unit 2, it is evident that the pi~obability of crack formation in these.turbine discs is significantly SJreater than previously assume*d by the vendor *. In 1ight of this information and the actions being taken by the, licensee-users9 w2 con:3ider. this warrants your prompt full UT inspection of LP rotor discs, especially the keyways and bore areas, and. docurnentation to the NRC of yotff justif"ication for continued operation until such *inspections are made and aJl defects thus-identified
. are corrected.
Therefor"e, in accordance vdth 10 CFR 50.5llr(f), you are requested to provide v1ithi n 20 days of the date of this letter, or* in any event prior to*restart if your units are not operating~ written statements, signed under oath or affirmation, which will enable the staff to determine v1hether or not your license to operate Surry* PoHcr Station~ Unit No. 1 should be :nodifled~ suspended, or revoked.
- \\s part of -your statement, you sho~tlcl provide and address the safety significanc2 of the information,,..--
- *-"'I requested in Enclosure 2 to this letter.
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£JURNAME:)il,,-
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- NllC FORM 3Ul (9-76) NRCM 0240 u.s. GOVERNM 0
ENT PRINTING OFF Ice: 1978 - 205 - 769 I
~r. J. H. Ferguson
.,.. 2 -
It is my understanding that -key\\,iay craeks have 'been _itlentifi'e_d in *discs in_
1 ow pressure turbines at Surry Unit N_o-. 2 and you have made the r:iecessary
- repairs.
We req~est that -the results of your turbine inspection, a
- description of corrective actions *taken, and justification that-this action was suffic~ent to permit return{n~ this unit to operation be ~eported t6
- us \\-Jithin 20 days-of the date of this letter.
We also request th9t you provide the informati'on listed in Enclosure 2 to this letter*fo'r Surry Unit No. 2 and*your assE;ssment of the_ safety significance of your responses.
Pl ease contact. us if you have any questions concerning these req~ests.
Because of the general nature of the information-sought -in Encl.cisure 2 we are trans'mitting a copy of this enc1osure to klestinghouse ',
by separate letter.
As discussed in the December 17,
- 1979 meeting \\'le.
ur*ge you to address the generic aspects of this. problem and to *c'oprdinate your r-,esponses thrpugh
- an ovmer_' s group. __
C' *
. 1
- i,ncere y,
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. *,Original Signe<f Bf Darrell G. Eisenhut, Acti.ng'* Director
, Division of Operating R~ac~ors
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Enclosures:
- 1. - IE Informati*on Notice No... 79-37
\\
- t*li th Errata.Sheet
- 2.,Request for-Information Related to.
.,\\*_*,,..
'- \\' '
-Turbine Oi-sc *Cracks 20 Day Response,
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cc:
t4enclosures See next page
- SEE PREVIOUS YE~LOW FOR CONCURRENCES
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OF'FICE-~
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NRC FORM 318 (9-76) NRCM: 0240 '
- 1
~
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, U.IJ. _GOVERNMO:NT PRINTING OFFICE!: 1970
- 265
- 769
Docket Nos. 50-280 and 50-281 Mr. J. H. Ferguson Executive Vice President - Power Virginia Electric and Pm*1er Cpmpany Post Office Box 26666 Richmond, Vi rgi ni a 23261
Dear Mr. Ferguson:
On December 28, 1979 e NRC Office of Inspection and Enforcement issued Inforrnati.on Notice No.
9-37 that I resented information available to the staff related to the iscovery of cracks in the keyway and bore sections of t~estinghouse lo O rpm ow pressure turbines.
A copy of this Information Notice witn errat sheet is enclosed.
lfo$tinghouse notified utility u ras of this potential problem on October 30, 1979 and lvas requested by the sta {.. !o present a similar -briefing in.
Bethesda, Maryland on December 17, ~79.
You were contacted on December 14, 1979 and invited to send represe_ *at1ls to the staff _briefing and also were requested to advise the sta f of 11e act i ans bei,ng taken in regard to this potential problem at you; operat* g nuclear prn*1er plant.
\\4estinghouse was later requeste4 to meet a ain with the staff and licensee-users on Janyary 8, 1980 tosuptlement the formation provided in the earlier nieetit1g and in interimt~rrespondence,ith the staff.
On the basis. of information prfvided by L<lestingho se and recent indications from turbine':.ctisc inspections r,ow underway at Arka,\\as Nuclear One Unit 1, Beaver V~)ley Unit 1 and Indian Point Unit 2, it,~ evident that the probabi-lit.X O'~ crack forrr}tion in these turbine dfsc~ is ~ig~ificantly greater than prev1 ously assumed and the energy of a tur~ ne m1 ss1 le could be greater than postullffted by the vendor in earl i:~afety analyses.
we consider the greater pot<:;,i1tial for damage to safety syst 1s in your In light of this information and the actions being taken bs*he licensee-users~
plant warrants your prompt full UT inspection of LP rotor dis s; especially the keywa.ys and bore areas,/ and documentation to the NRC of yol\\f justifica-tion for continued operatign until such inspections are made ancl\\.all defects thus identified ari corrected. Therefore, in accordance \\iith date of this letter, or i
- any event prior to restart if your units\\
10 CFR 50.54(f), you are ?quested to provide within 20 days of t11\\
are not operating, writte, statements, signed under oath or affirmat,1,n, which wi 11 enable the staff. to det~rmi ne whether or not.yo~ r 1 i cense to operate Surry Pm*ter Stlat1on, U111t No. 1 should be modified, suspended, or revoked. fs part of your statement, you shou)d provide and address the safety significance of the information requested in to this letter.
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OFFICE~.*.......*........*............. *****
SURNAME~................. *....... **.*.. *****
DATE~.........*.......................................................... *.......................................
NRC FORM 318 (9-76) NRCM 0240
-.t:ru.s. GOVERNMENT PRINTING Of:'FICE: 1979-289-369
....
- It is my understanding that keyway cracks have been identified in discs in low pressure turbines at Surry Unit No. 2 and you have made the necessary repairs.
We request that the results of your tL bine inspections, a description of corrective actions taken, andju tification that this action was sufficient to permit returning this unit t ope,ati on be. reported to us within 20 days of the date of this letter.
We also request that you provide the i nforrnation 11 sted in Enclosure 2 to this 1 etter for Surry Unit No. 2 and your assessment of the safety significan,::. of your responses.
Please contact us if you have any questi s concev:n* ng these requests.
Like\\vise., you are requc$ted to provi :.. and. i~dress tile safety significance of the information in Enclosure 3 \\vi th*. 6 days of the date of this 1 etter.
Because of the general nature of the infol'inc.::tfon sought in Enclosures 2 and 3 we are transmitting a copy of th se e1 1 osures to tfostinghouse by separate letter.
As discussed in the D(;icembe 17, 1979 meeting we urge you to addrass tile generk aspects of this pro
~m and to coordinate your responses through an oi'mer' s
Enclosures:
- 1.
IE Information Notice No. 79-37 With Errata Sheet Darrell G. £isenhut, Acting Director Division of Operating Reactors
- 2. Request for Information Related to Turbine Disc Cracks - 20 Day Response
- 3. Request for Information Related to Turbine Disc Cracks - 60 Day Response cc: w/enclosures See next page NRC FORM 318 (9*76) NRCM 0240 sf:ru.s. GOVERNMENT PRJN~JNG OFFICE: 1979-289*369
e e
UNITED STATES NUCLEAR.REGULATORY-COMMISSION
. WASHINGTON, D. C. 20555 Docket Nos. 50-280 and 50-281 Mt. J. H. Ferguson Executive Vice President - Power Virginia Electric and Power Company Post Office Box 26666 Richmond, Virginia* 23261
Dear Mr. Ferguson:
February 25, 1980 On December 28, 1979 the NRC Office of Inspection and Enforcement issued Information Notice No. 79-37 that presented information available to the staff re 1 ated to the discovery of cracks in the k eyway and bore sections of Westinghouse 1800 rpm low pressure turbines.
A copy of this Information Notice with errata sheet is enclosed.
Westinghouse.notified utility users of this potential problem on October 30, 19.79 and was requested by the staff to present a similar briefing in Bethesda, Maryland on December 17, 1979.
You were contacted on December 14, 1979 and in~ited to send representatives to the staff briefing~nd also were requested to advise the staff of the act i ans being taken in regard to this potential problem at your operating nuclear power plant.
Westinghouse was later requested to meet again with the staff and. licensee-users on January 8, 1980 to supplement the information provided in the earlier meeting and in interim correspondence with the staff.
Ori the basis of information provided by Westinghouse and recent indications from turbine disc inspections now underway at Arkansas Nuclear One Unit 1, Beaver Valley Unit 1 and Indian Point Unit 2, it is evi.dent that the probability of crack formation in these turbine discs is significantly greater than previously assumed by the vendor.
In light of this information and the actions being taken by. the licensee-users, we consider this warrants*
your prompt full UT inspection of LP rotor discs, especially the keyways and bore areas, and documentation to the NRC of your justification for continued operation until such inspections are made and all defects thus identified are corrected.
Therefore, in accordance with 10 CFR 50.54(f), you are requested to provide within 20 days of the date of this letter, or in any event prior to restart if your units are not operating, written statements, signed under oath or affirmation,which will enable the staff to determine whether or not your license to operate Surry Power Station, Unit No. 1 should be modified, suspended,* or revoked.
As part of your statement, you should provide and address the safety significance of the information requested in Enclosure 2 to this letter.
e Mr. J. February 25, 1980 It is my understanding that keyway cracks have been identified in discs in.
low pressure turbines at Surry Unit No. 2 and you have made the necessary repairs.
We request that the results of your turbine inspection, a description of corrective actions taken, and justification that this action was sufficient to permit returning this unit to operation be reported to us within 20 days of the date of this letter.
We also request that you provide the information listed in Enclosure 2 to this letter for Surry Unit No. 2 and your assessment of the safety significance of your responses.
Please contact us if you have any questions concerning these requests *.
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 generic aspects of this problem and to coordinate your responses through an owner's group.
Enclosures:
- 1.
IE Information Notice No. 79-37 With Errata Sheet
- 2.
- Request for Information Related to Turbine Disc Cracks - 20 Day Response cc:
w/enclosures See next page
Mr. J. H. Fergu so.n Virginia Electric and Power Company
- 3 _
cc:
Mr. Michael w. Maupin Hunton and Williams
. Post Office Box 1535 Richmond, Virginia 23213 Mr. w. L. Stewart, Manager P.O. Box 315 Surry, Virginia 23883 Swem Li bra ry College of William and Mary Williamsburg, Virginia 23185 Donald J. Burke
- u. s. Nuclear Regulatory Corrmission Region II Office of Inspection and Enforcement 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 ro:r--~*-.-.. --- ---*--
February 25, 1980
f I
UNITED STATES*.
NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, O.C.
20555 December 28, 1979 1SIN$ NO.:
6870 Access ion No.:
7910250525 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS D0scription 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 50.55e and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Wcsfinghouse 1800 rpm low pressure turbine discs.
Westinghouse had ~ade a presentation on the turbine disc cracking to electric utility executives on October 30, 1979.
Telephone disc11ssions between the NRC staff and Westinghouse's Turbine Divisi~n on Nove~ber 20, 1979 established that cracking, attributed to stress corrosion p~enc:~cna, had been found in the keyway areas of several LP turbine discs at ope:*ating plants 2nd that inservice inspection techniques (i.e., in situ ultra-sonic l2Xa.minaticn) for crack detection have been developed and are being imple-G2r1ted in the fiPld.
The Office of Inspection and Enforcement was also notified on HQve~ber 20, 1979 that during the current overhaul of Commonwealth Edison's Zion Unit 1 LP turbine, ultrasonic examination revealed embedded cracks located on the inlet si,~e on the disc bore area where no cracks had been previously o~served.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than the key,.,,ay cracks found to date.
Accardi ng to We~ti nghouse, 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 m~chanism and impact on disc integrity is being further evaluated by ~estinghouse.
A meeting was held on December 17, 1979 between the NRC staff, Westinghouse and utility representatives to discuss the disc cracking problem, repair alter-natives~ turbine ~issile evaluation, inspection techniques and plant inspection priorities.
In respJnse to the staffs 1 request, Westinghouse provided the staff an updated r~port on December 21, 1979 regarding the current field inspection program that included a list of nuclear power plants already inspected, recom-mended inspection schedules and pertinent information related to LP turbines where cracks have been observed.
Inspections to d~te have identified turbine disc cracks at Surry Unit 2, Point Beach Unit 2, Palisades, Indian P~int Unit 3 2nd Zion Unit 1.
All units except Point Beach Unit 2 will make repairs before the plants return to power.
Point Beach returned to power on December 23, 1979 with a sr:ia1l crack in the No. 2 disc of LP Turbine No. 2.
An analysis by Westinghouse indicated that the observed crack will not attain critical dimensions during 28 additional months of turbine operation.
The NRC staff is evaluating*
the turbine inspection results and analysis by Westinghouse.
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e IE InfonJation Notice No. 79-37 e
December 28, 1979 Page 2 of 2
\\.i'estinghouse also notified the staff that extrap'olation of information obtained from InJi~n Point Unit 3 inspection and analysis indicates that disc cracking could be significant at Indian Point Unit 2 and the turbines should be inspected
~cur,er 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. lists the PWR plants having Westinghouse 1500/1800 rpm turbines.
The~~ category represents those turbines which appear to have the earliest need for inspection.
With the exception of Yankee Rowe, Westinghouse has n:!cor::-;,e:nded 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 remaining machines of the Category A i~la.nts 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 inspection of those PWR plants having other interfacing turbine designs sho~n in Enclosure 2.
Changes to the fore~entioned inspection schedules proposed by
~.*estinghouse r.:ay be necessary,,s ne*n' L*chriical infon::ation beco!iles available.
From the infor~~tion 2vailable to the NRC staff at this time it appears that
,:rad:fog,:*,2.y Le ;.1.:ffe s':ner'ical1y 'n'ic:r::sp,P.ad in turbine discs (e.g., keyways and hare areas) than previously observed.
It is important to note that the UT inspections p1::rfcrmed by Westinghouse thus far were essentially l irnited to the ke)'\\'.'ays (disc outlet) of selected discs \\o.1hereas the Zion Unit 1 inspection results indicate that examination of the disc bore section must be taken into account.
Also, h'estinghouse is currently re-evaluating their previously estimated turbine missile energies based on recent missile test results from model sy~metric and non-syG~etric missile i~pact tests.
Their preliminary findings, although subject to ch2nge,,,ow indicate possible higher missile exit energies in some rases than previously e~pect~d.
This Information Notice is provided as an early notification of a possibly significant rr.atter, the allegations and the generic safety implications of which are cur;*ently undergoing review by the NRC staff.
It is expected that recipients will review the information applicable to their facilities.
If NRC evaluations so indicate, further licensee actions may be requested or required.
Erabedded cracking in key\\*,ays -and disc bore areas. have been observed only in Westinghouse LP turbines thus far.
However, the NRC staff belieyes that turbines of other Ganufacturers should be included in consideration of this problem.
No ~ritten response to this Information Notice is required.
If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Enclosures:
As stated
e UTILITY Florida, P&L Conso 1 i dated rn.
!;ASl~Y A1*k.::nsas P&L VEPCO Carolina P&L So. Calif. Ed.
Yankee A.P.
Wisc. Mich. Pwr.
Consurn.::rs P'n'r.
Commonwealth Ed.
Commonwealth Ed.
Florida P&L Nebraska PPD Wisc. Mich. Pwr.
i*;aine? Y2nkce Rod.ester G&E "orthE ;*n s*;.. -*t.cs
'..'-i~c. iJ.S *
. -~..
- . t
- Encfosure 1
- CATCGORY AA STATION Tu; key Point Indian Point Indian Point Russellville Surry -
Robinson San Onofre Rowe Point Beach Palisades Zion 1 Zion 2 Turkey Point Cooper Point Beach Bai ky Pufot Ginna Prairie Ts1z,nd e
UNIT 3
2 3
1 1
2 1
1 1
1 1
2 4
1 2
1 1
1 1
e -(go~tin~ed)
UTILITY A1aba:;;a Po'n'er A 12b2r:,a Po*n*er Baltimore G&L Carolina P&L Carolina P&L Carolina P&L Carolina P&L Cincinnati G&E Corr.i"IOffn'ea 1th Ed.
Cor.,:r,om-;ea l th Ed.
Co;c-:*:ior:*n*ea 1 t.h Ed.
Cr._* ')u*,:,,-2 l t.h Ed.
Co,,r,ec"t. i cut Yankee Duke P0r,er Duke Pm-,er Duqt.:2sne Lt.
Duquesne Lt.
Duquesne Lt.
Flordia Pc*n*er Flordia Po.,.,.er Flordia Power Houston L&P Houston L&P Corp.
& Lt.
& Lt.
Louisiana P&L Metropolitan Ed.
Northern States Pwr.
Pub. Service E&G Pub. Service E&G Pacific UE Pacific G&E CATEGORY A STATION Farley Farley Calvert Cliffs Harris Harris Harris Harris Byron Byron Braidwood Braid'n*ood Hadd2m Neck McGuire McGuire Shippingport Beaver Valley Beaver Valley Crystal River St. Lucie St. Lucie So. Texas So. Texas
\\..'aterford Three Mile Isla~d Prairie Island s*a, em Salem Di'ablo Canyon Diablo Canyon UNIT 1
2 2
1 2
3 4
1 1
2 1
2 1
1 2
1 1
2 3
1 2
1 2
3 2
i 1
2 1
2 Page 2 of 3
e P.S. Indiana P.S. Indiana Puget Sound P&L SMUD.
1VA n1A TVA 1VA VEPCO VEPCO VEPCO 1/i:.PCO VEPCO
\\-.'P?SS
'n'PPSS
'r.'PPSS
'ri'P PSS
~nclosure 1 :(Gontin~ed)
. CATEGORY A STATION Marble Hill Marble Hill
~-
Skagit Rancho Seco Sequoyah Sequoyah Watts Bar Watts Bar North Anna Horth Anna North Anna r;0rth r-.r.na r,orth,;nna H.,:,lCl'd
'n't~ p s WNPS
'n'/iPS 1n'liPS e
UNIT 1
2 1
1 1
2 1
2 1
2 3
4 2
2 1
3 4
5 Page 3 of 3
UTILITY Duke Po.. *er Co.
Duke PO\\,*er Co.
Duke Po.... *er Co.
OPPO Baltimore Electric
& Gas Metropolitan Edison Indiana & Michigan Electric Indiana & Michigan Electric Northeast Utilities Portland General Electric Toledo Edison Arkansas Power &
I_~ ght
\\..'r*PSS Encl:oS'I.Jre 2
- STATION Oconee Oconee Oconee
~*
Ft. Calhoun Calvert Cliffs Three Mile Island D.C. Cook D.C. Cook Mi 11 stone Trojan
. Davis Besse Ar~ans~s Nuclear One Hanford e
UNIT 1
2 3
1 1
1 1
2 2
1 1
2 1
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e e
Errata Sheet For IE Information Notice No. 79-37 Pagel, ps.ragraph 2, line 9:
Change "inlet" to "outlet 11 Pagel, paragraph 3, lines 9 and 10:
Change "Point Beach Unit 2" to "Point Beach Unit l"
?age 1, paragraph 3, line 10: After Point Beach Unit 1 add an asterisk
("*") footnote and place a note at the bottom of the page as follows:
"*Hisconsin Electric Power Company orally notified the NRC project.
manager on ~ovember 5 that turbine disc cracking had been observed at Point Beach Unit l.
11
- line 4:
Change "Russell vil 1 e" to "ANO" ' line 8:
Change to read:
"Yankee Atomic Electric, Yankee Rowe" ' 1 ines 9 and l 5:
Change 11\\nsc Mich Pwr" to "Wisc El ec Pwr 11 ' line 16:
Ci1,*: nge to r2ad "i"~a i ne Ya n!:2e :'\\'comic r*-,,r, i<~ i ne Yankee"
- page 3, line 13:
Delete as redundant reference to North Anna 2
~
e REQUEST FOR INFORMATION RELATED TO TURBINE DISCS SITE SPECIFIC GE~ERAL QUESTIONS - To BE :ompleted in 20 Day~
- l.
Provide the following information for each LP turbine:
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 properties data
- 3.
toughness properties data including Fracture Appearance Transition Temperature and.upper energy and temperature
- 4.
keyway temperatures
- 5.
calculated keyway crack size for turbine time specified in "B" above
- 6.
critical crack size
- 7.
ratio of calculated crack to critical crack size
- 8.
crack growth rate
- 9.
calculated bore and keyway stress at operating design overspe<::d
- 10.
calculated K1c data
- 11.
~ininu~ yield strength specified for each disc II.
- Provide details of the results of any completed inservice inspection of LP turbine rotors, including areas examined, since issuance of an operating license.
For each indication detected, provide details of the location of the crac~. its orientation, and size.
III. Provide the noninal w~ter chemistry conditions for each LP turbine and describe any condenser inleakages or other significant changes in secondary water che~istry to this point in its operating life. Discuss the occurrence of cracks in any given turbine as related to history of secondary water chemistry in the unit.
IV.
Ifyour plant has not been inspected, describe your proposed schedule and approach to ensure that turbine cracking does not exist in your turbine.
V.
ffyour plant has been inspected and plans to return or has returned to power with cracks, provide your proposed schedule for the next turbine 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 the staff. If such an analysis and evaluation has been performed and reported, please provide appropriate references to the available documentation.
In the event that such studies have not been made, consideration should be given to scheduling such an action.
e e GENE:R_l_f QUESTIONS - To Be Completed 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/replacener.t procedures for the faulty discs.
III. What i1m1ediate and long tenn actions are being tak:n by Westinghouse to minimize future stress c.orrosion problems with turbine discs?
What actions are being recorrmended to utilities to ~ininize stress corrosion cracking of discs?
rv.
Identify the impurities known to cause cracking in the 1 ow pressure turbines, and their sources. Di~cuss the relationship between.steam generator chemistry and steam chemistry relative t: the introduction of corrosive impurities into the turbine, inclucin; phosphate, AVT, ZST, and BWR chemistry. Discuss the mechanisrr of :epositi.on 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 stear:: S!paratiori portion of the steam generator have on scrubbing corrosive irrtu!"itie[ fror.i the steam?
VI.
To what extent can the buildup of corrosive i~uri:ies in the LP turbine be alleviated? What would be the effects ~f the following actions:
VII.
VIII.
- 1. Pumping moisture separator condensate to cor.de:ser?
- 2.
Periodically moving point of conder:sation tc ~-event localizea buildup of corrosive.impurities?
Describe fabrication and heat treat"'lent sequen:e f~r discs, including thermal exposure during shrinking operations.
Discuss the effects of any local residual stresses on the cracking mechanism.