ML18081B193
| ML18081B193 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Librizzi F Public Service Enterprise Group |
| References | |
| NUDOCS 8003140477 | |
| Download: ML18081B193 (16) | |
Text
FEBRUARY 2 _ 5 1990 Docket Mo.
50-272 Mr. F. P. Librizzi, General Manager Electric Production Production Department Public Service Electric and Gas Company 80 Park Place, Room 7221 N m1 ark, N evJ J e rs ey
- 0 71 0 l
Dear Mr. Librizzi:
On December 28, 1979 the NRC Office of Inspection and Enf orcernent 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 Wesiinghouse 1800 rpm low pressure.turbines.
A copy of this Information Notice with errata sheet is enclosed.
t,Jestinghouse notified utility users of this potential problem on October 30, 1979 and v1as requested by the staff to present a similar brieffrig in Bethesda? Maryland on December 17, -1979.
You \\*Jere contacted on December 14, 1979 and invited to send representatives to the staff briefing and also vfere requested to advise the-staff of the actions being taken in re~urd to this potential* problem at your operating nuclear fJO\\'ier plant.
Westinghouse was later requested to n~et again with the staff and licensee-users on January 3, 1980 to suppler;1ent the information provided in the earlier meetin9 and in interim correspondc:nce with the staff *.
On 'the basis of information provided by \\'restinghouse and recent ind*ications fr-on; turbine disc inspections no1i-1 undeniay at Arkansas Nuclear One Unit 1, Beaver Valley Unit 1 and Indian Point Unit 2, it-is evident that the probability of crack formation in these turbine discs is significantly greatf::r than previously assumed by the vendor.
In light of this information and the actions bein9 taken by the licensee-users, we consider this warrants your prompt full UT inspection of LP rotoe* disc~, especially the key)*1ays and, bore areas, and documentation to the NRC of your justific~tian for continue~
operation until such inspections are made and all defects thus identified
\\
are corrected *. Therefore, in accordance vlith 10 crn 50.~)L~(f), ycu are
\\
rer;uested-to provide i;1ithin 20, days of the date of this letter, or in any event prior to restart if your.unit is not operating, v1ritten statements, signed under oath or affirmation, 1;Jhich wi11 enable the staff to determine
".'.'f1ether or not your license to operat<:: Salem, Unit No. *l should be a
modified, su~pended, or revoked.
As p~ri of your statement, you should fl~1 I
pro vi de and address the safety si gni fi ca net: of the i nfor:nat ion requested,/\\
1 ~~~~--~.-~-*H-l
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DATE~
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me !'ORM 310 (9-76) NH.CM 0240
- -U.S. GOVE.RNMENT PRINTING OFFICE: 1970 - 265 - 709
~
OFFICE?>
CURNAME~
DATEii>
Mr. F. P.* Librizzi Because of the general nature of the information sought in Enclosure 2 v.1e are transmitting a copy of this enclosure to Hestinghouse by separate letter.
As discussed in the December 17, 1979 meeting -~*1e urge you to address the 9ner:ic aspects of this problem and to coordinate your responses through an mmer's group.
Enclosures:
- 1.
IE Information Notice No. 79-37 With Errata Sheet
- sincerely, Orlgi nat' Signe'! By, Darrell G. Eisenhut, Acting Director Oivi~ion of Operating Reactors
- 2.
Request for Information Related to Turbine Disc Cracks - 20 Day Response cc: \\'!/enclosures See next page w¥ ~~J/fll.
- SEE PREVIOUS YELLOW FOR CONCURRENCES
.°.°.~ '.°.~B*l*~.... ~i:~*~:~l :~..j *~i:~~;; i-~P....... ~~~~*t*....................... '*........... *...........
~JRo.s.s. :.pa.b..................... _...................................................................................... '.............................
J.2.3/B.O................ l/2?l/80............ 1/25/8.Q............ D.!)/.lf.g.Q....................................................... :,......
NRC FORM 318 (9-76) l\\TRCM 0240
~
I I
I 1
- U.S. GOVERNMENT PRINTING OP"FICI:!: 1978 - 2G5 - 769
Docket No. 50-272 Mr. F. P. Librizzi, General Manager Electric Production Production Department Public Service Electric and Gas Company 80 Parf Pl ace, Room 7221
\\ '
Newark, New Jersey - 07101
- oearMr. Librizzi:
On December*2s;*_ 1979 the NRC Office of Insp ction and Enforcement issued Information Notice No. 79-_37 that presented' informatfon available to the staff related to the discovery of crack in the keyway and bore sections of Hestinghouse 1800 rpm low pres ure turbines.
A copy of this Information rtotice with errata sheet s enclosed.
- Westinghouse notifie~ utilit users of ti s potential problem on October 30, 1979 and was requested by the taff top esent a similar briefing in Bethesda, Maryland on December 7, 1979 You were contacted on December 14, 1979 and invited to send represe tative to the staff briefing and also were requested to advise.the staf of 1e actions being taken in regard _.
to this potential problem at your o - r, ting nuclear power -plant.
Westinghouse \\qas later requested to et again Nith the staff and licensee-,-
users on January 8, 1980 to s*upplerne he information *provided in the
.earlier meeting arid in interim corre pon ence with the. staff.
On the basis of information provide by Hes inghouse. and recent indications from turbine disc inspections now-derway a Arkansas Nuclear One Unit 1, Beaver Valley Unit 1 and Indian Point Unit
, it is evid<:mt that the probability of crack forrriatio in these tur ine discs is significantly greater than.previously assumed ad the energy o a turbine missile could be greater than postulated
~ the vendor in rlier safety analyses.
In light of this information and the actions being ken by the licensee-users, we consider the greater potenti l *for damage to safet systems in your plant warrants your prompt full UT inspection of LP.rot discs, especially the keyways. and bore areas, an documentation to the NRC f your justifica*-
tion for continued operation until such inspections are ma e and all
.defects thus identified are corrected. Therefore, in accor nee with 10 CFR 50.54(f), you are requested to provide within 20 days f the date of this letter, or in any event prior to restart if your unit is not operating, written stafements, signed under oath or affirmation,
~Jhi ch wi 11 enable the staff to deterrni ne whether or not your 1 i cense to operate Salem, Unit No. 1 should be modified, suspended, or revoked.
As part of your Statement, you should pro vi de and address the safety
. significance of the information reqµested in Enclosure 2 to this letter.
OFFICE~,--........................ -..........
.. S~RNAME.....................................
D~TE., *.......***.................. _......
N~C FORM 318 (9*76) NRCM 0240
"(:{u.s. GOVERNMENT PRINTING OFFICE: 1979-289-369
'-:_ Likewise, you are requested to provide and add re" t e safety si gni fi cance of the information in Enclosure 3 within 60 da,Y.
of the date of this 1 etter.
Because -of the general ature of the inform ion sought in Enclosures 2 and 3 we are transmi tt
- ng a copy of thes enclosures to i~esti nghouse by separate letter.
As d cussed in the ecember 17, 1979 meeting we urge you to address the ge ric aspects f this problem and to coordinate your responses through an ow.r's grou *
Enclosures:
- l.
IE Information Noti No. 79-37 Sincerely,
-rrell G. Ei senhut, Acting Di rector Di ]sion of Operating Reactors With Errata Shee.t'
- 2.
Reouest for Infor-tfiation 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 pag OFFICE~. _qog; ~(LQ..... P.o~.=.o~.
su~NAME~.. WJRoss.:/b \\... AS.chwe.. r_...
DATE~---~~!.~?!.~~-.. -.... ~.1. I ;t_. ~-~ -....
NRC FORM 318 (9-76) NRCM 0240
. -Uu.s. GOVERNMENT PRINTING OFFICE: 1979-289-369
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 Docket No.
50-272 Mr. F. P. Librizzi, General Manager Electric Production Production Department February 25, 1980 Public Service Electric and Gas Company 80 Park Place, Room 7221 Newark, New Jersey 07101
Dear Mr. Librizzi:
On December 28, 1979 theNRC 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 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, 1979 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 invited to send representatives to the staff briefing and also were requested to advise the staff of the actions 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.
On 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 evident 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 unit is not operating, written statements, signed under oath or affirmation, which will enable the staff to determine whether or not your license to operate Salem, 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.
- I Mr. F. February 25, 1980 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
- incerely, Darrell G. ~~e~Director Division of Operating Reactors
- 2.
Request for Information Related to Turbine Disc Cracks - 20 Day Response cc:
w/enclosures See next page
Mr. F. P. Librizzi Public Service Electric and Gas Company cc:
Mark J. Wetterhahn, Esquire Conner, Moore and Corber Suite 1050 1747 Pennsylvania Avenue, NW.
Washington, D. c.
20006 Richard Fryling, Jr., Esquire Assistant General Solicitor Public Service Electric and Gas Company 80 Park Place Newark, New Jersey 07101 Gene Fisher, Bureau of Chief Bureau of Radiation Protection 380 Scotch Road Trenton, New Jersey 08628 Mr. Hank Midura, Manager Salem Nuclear Generating Station Public Service Electric and Gas Company 80 Park Place Newark, New Jersey 07101 Mr. R. L. Mittl, General Manager Licensing and Environment Public Service Electric and Gas Company 80 Park Place Newark, New Jersey 07101 Salem Free Library 112 West Broadway Salem, New Jersey 08079 Leif J. Norrholm -
U. S. Nuc.lear Regulatory Commission Drawer I Hancocks Bridge, New Jersey 08038
.February 25, 1980
"I u~n HD
~ d\\ 1 F.S l~UCL[/,R REGUl.AI URY COMMISSION Off ICE Of INSPECTION AND ENFORCEMENT h'ASHINGTON, D. C.
20555 Decemb2r 28, 1979
!SINS NO.:
6870 Access ion No.:
7910250525 IE Information Notice No. 79-37 C?.1\\CKING IN LOW PRESSURE TURBINE DISCS Description of Circumstances:
An anony~ous 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 conosion c1*2ck.ing in li'estinghouse 1800 rpm low pressure turbine discs.
Westin~hcuse had ~ade a presentation on the turbine disc cracking to electric utility executives on October 30, 1979.
Telephcne discussions between the NRC staff and Westinghouse's Turbine Division on 1~c,*.-2:.:be1* ?.O, 1979 established that cracking, attributed to stress corrosion p',en'.:.:,na, f1.3d teen found in the keyway areas of several LP turbine discs at operating pl~nts 2nd that inservice inspection techniques (i.e.* in situ ultra-sonic cxami1.~tion) for crack detection have been developed and are being imple-mented in tfle field.
The Office of Inspection and Enforcement was also notified on Ho-.._:;,,~e:r 20, 1979 that during the current overhaul of Commonwealth Edison's Zion !!nit 1 LP turbine, ultr."'!sonic examination revealed embedded cracks located on e1e inlet side on the disc bore a1-ea where no cracks had been previously o~s~rved. Ultr2sonic ~easurements indicate this disc bore cracking is of greater depth t:-ian the keyway cracks found to date.
According to 'r.'e~tinghouse, these bore cracks hcve been metallurgically examined *and preliminary findings show them not to ce typical of classical stress corrosion cracking observed in the keyv:ays.
The p1ob2ble cr2cking mechanism and impact on disc integrity is being further e v a 1 ~ :'. t', d by 'n' e s t i n g ho us e.
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, tu1*bine ~issile evaluation, inspection techniques and plant inspection priorities.
In 1-csponse to the staffs' request, \\..'estirrghouse provided the staff an updated report 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 date have identified turbine
. disc cracks at Surry Unit 2, Point Beach Unit 2, Palisades, Indian Point Unit 3 and Zion Unit 1.
All units except Point Beach Unit 2 will ~ake repairs before the plants return to power.
Point Beach returned to power on December 23, 1979
'n'ith a small crack in the No. 2 disc of LP Turbine No. 2.
An analysis by
~~stinghouse indicated that the observed crack will not attain critical di~ensions during 28 additional oonths of turbin~ operation.
The NRC staff is evaluating the turbine inspection results and analysis by Westinghouse.
IE Infor;;;ation Noqce ~fo. 79-37 December 28 1 1979 Page 2 of 2 Westingho11se also notified the staff that extrapolation of information obtained from Indian Point Unit 3 inspection and analysis indicates that disc cracking could be significant at Indian Point Unit 2 and the turbines should be inspected soon2r than the spring outage of 1980.
The NRC staff is currently reviewing Coiisolidated Edison's plans for pro;1;pt evaluation* of this potential problem at this unit. lists the PWR plants having Westinghouse 1500/1800 rpm turbines.
The AA category repres~nts those turbines which appear to have the earliest need for inspection.
With the exception of Yankee Rowe, Westinghouse has recor,c.ended to utilities that inspection of these machines be completed by the Spring lSSO 011tage period.
The Ro~e unit is uninspectable by the present ultr2sonic techniques due to its design.
Westinghouse has recommended the rP.1:;aining rr.achines of the Catt:gory A plants be inspected as their service periods 2pproach five years or in the event significant corrosion problems become evident during this time. *The NRC staff is currently reviewing the ne~d for inspection of those PWR plants having other interfacing turbine designs shown in Enclosure 2.
Changes to the fore~entioned insprction schedules proposed by
'n'o~~;ti:1s:10:_*se :.::,y ::ie n2c'~~~s2i*y,:s r.e*,.; tc:..-:hnical infor1,F:tion b.;cor;;es c.vailable.
~rom the info;-~ation av2il2ble to the NRC staff at this ti~e it appears that t
11
- d., ***
(
d cr2cK1ng :-.::.y J2 1;,;:;re £'J1er1ca y....--102spr-,"'.:
1n c.Ul'Dlne CJ1scs e.g.,
~eyv;ays an bore ai*0as) tr *. -:.n prc:viously obs1:rved.
It is iliiportant to note that the UT inspections pt::rfori11cd by \\*:estin~house thus fat \\-:ere t;ss;~nti;~lly lir.dted to the key*n*2ys (disc outlet) of selected discs 1;*hercas the Zion Unit 1 inspection results indicate that examination of the disc bore section must be taken into account.
Also, ~estinghouse is currently re-evaluating their previously estimated turbine missile energies b2sed on recent missile test results from model symmetric and non-sy,;,;;ietric missile impact tests.
Their preliminary findings, although subject to ch~nge, now indicate possible higher missile exit energies in some c2ses than previously exp~cted.
This Information Notice is provided as an early notification of a possibly significant matter, the allegations and the generic safety implications of which are currently undergoing review by the :me staff.
It is expected that recipients will review the infor~ation applicable to their facilities.
If NRC evaluations so indicate, further licensee actions may be requested or required.
Embedded cracking in key>.. *ays -and disc bore areas have been ob_served only in 'r.'estinghouse LP turbines thus far.
However, the NRC staff believes that turbines of other manufacturers should be included in consideration af this problem.
l~o written response to this Information Notice is requfred.
If you have any
~~estions regarding this matter, please contact the Director of the appropriate
~RC Regional Office.
Enclosures:
As stated
_.._.,.,lfl~*m-~*-.:-""'*~r---.*--~,..'="'---....-.. ";"l.-.-~:~-~.---"'!.~---*
... *---**.... ****--..":'-***----....... _. ******-... -... -.... --r.>>*.-~.---.-*. * *
.e UTILITY r1 u d da, Pl'~L Ccr:rnlidc:.ted ED.
f?ASIN
.t.rk<:nsas P&L VEPCO Carolina P&L So. Calif. Ed.
Yankee A.P.
'disc. Hi ch. Pwr.
Consumers Pnr.
Co;.-.~.1onwea 1th Ed.
Com:nonw(Oa lth Ed.
\\</isc. Mich. Pwr.
M3ine Yc.nk2e Rochester G&E 1forU12rn s*: ;'~J'S
\\.'i:--r.. P.S.
[ncl cs~re 1.
CATEGORY AA STATION Turkey Point
~
Indian Point Indian Point Russellville Surry Robinson San Onofre Rowe Point Beach Palisades Zion 1 Zion 2 Turkey Point Cooper Point f)p;:och 8.:ilcy ?o*int Ginna Prairi>: Tsic-nd
!~*.. L.~ u;,.*~e UNIT 3
2 3
1 1
2 1
1 1
1 1
-2 4
1 2
1 1
1 1
~~~~~~~
....... --... ~--1-""':*"""-'>T°;:.~..-.:-
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.---.:"'~~~
-*-----41
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Enclosure l*(Continued)
UrIUTY Al 2b2r~.a Por.*er A 1 ab arr.a Po;.,*er Baltimore G.9iil Carolina P&l Carolina P&l Carolina P&l Carolina P&l Cincinnati G&E Cor::.-:-1or.*,,*ea 1th Ed.
Cor.,-:-01l'neri 1th Ed.
Co1.-*0!'.*.. 22Hh Ed.
C' (. ;~_--. 01:*,.,*,*c 2. l th [ d.
Duke Pc'r*er Duke Po*.. *er D1_1quesne Lt.
Duquesne Lt.
Duquesne Lt.
Flo1dia Pc*,,*er Corp.
Flordia P*m-,.e r Flordia Pc'n'er Houston L&P Houston L&P Louisiana P&l Metropolitan Ed.
Lt.
Lt.
Northern States Pwr.
P*1b. Service E&G Pub. Service E&G Pacific G.3.E Pacific G&E CATEGORY A STATION Farley Farley Calvert Cliffs Harris Harris Harris Harris Zim:tter Byron Byron Braidwood S ra i d*n'ood Hadd~m 1~eck McGuire McGuire Shippingport Beaver Valley Beaver Valley Crystal Ri ve:r St. Lucie St. Lucie So. Texas So. Texas Waterford Three Mile Island Prairie Island Salem 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
2 1
2 1
2 Page 2 of 3
ur11_1rv P.S. Indiana P.S. Indiana Puget Sound P&l SHUD.
\\'lPCO VEPCO
~, :*riss
'r,'PPSS
'n'PPSS
'n'PPSS
'n'?PSS (Continued)
CATEGORY A STATION Marble Hill l'.arble Hill Skagit Rancho Seco Sequoyah Sequoyah
\\..'atts Bar Watts Bar North Anna North Anna North Anna
!forth Anna
!forth Anna H.=ir1*~ord
'n'1~PS WNPS
\\i'NPS
\\*.'HPS 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 Power Co.
Duke Po*... er Co.
OPPD Ba1t1more Electric
& Gas Metropolitan Edison Indiana & Michigan Electric Indiana & Michiaan Electric
~
~6rtheast Utilities Portland General Electric Toledo Edison Arkansas Po~er &
Light
'n'PPSS STATION Oconee Oconee Oconee Ft. Calhoun Calvert Cliffs Three Mile Island D.C. Cook D.C. Cook Millstone Trojan Davis Besse Ark~nsas Nuclear One 1-:anford UNIT 1
2 3
1 1
1 1
2 2
1 1
2 1
. f Errata Sheet For IE Information Notice No. 79-37 Pagel, paragraph 2, line 9:
Change "inlet" to "outlet" Pagel, paragraph 3, lines 9 and 10:
Change "Point Beach Unit 2 11 to "Point Beach Unit 1 11 Pagel, paragraph 3, line 10: After Point Beach Unit l add an asterisk
("*") footnote and place a note at the bottom of the page as follows:
"*Wisconsin Electric Power Company orally notified the NRC project manager on November 5 that turbine disc cracking had been observed at Point Beach Unit 1.
11 Enclosure l ' line 4:
Change "Russellville" to "ANO" Enclosure 4
l ' line 8:
Change to read:
"Yankee Atomic Electric, Yankee Rowe" Encl OS Ur"e l ' 1 ines 9 and l 5:
Change "Wisc !'.i ch P1-1r" to "\\~is c El ec Pwr" F.nc 1 os t;re l ' 1 foe 16:
Change to rr-:d 11 i~aine Ye. rkce Atoi1-iic P;*;r, !-'.a ine Ya~1kce" Enclosure l ' page 3, line 13:
Delete as redundant reference to North Anna 2
REQUEST FOR INFORMATION RELATED TO TURBINE DISCS SITE SPECIFIC GE~~RAL QUESTIONS - To B~ ~ompleted in 20 Days
- 1.
Provide the following information for each LP turbine:
A.
Turbine type B.
Nur.1ber 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 overspei::d
- 10.
calculated K1c data
- 11.
1~iinirnir. yield strength specified for each disc II.
Provide details of the results of any completed inservice inspection of LP turbine rotors, including areas exa~ine~. 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 water che~istry conditions for each LP turbine and describe any condenser inleakages or other significant changes in secondary water chemistry 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.
ffyour 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.
_J
- GENERIC QUESTIONS - To
- ~~ Completed in 20 Days I.
Describe what quality control and 1nspection 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 irir.lediate and long tenn actions are being tak:n by Westinghouse to minimize future stress c.orrosi on problems with turbine discs? What actions are being reco1T111ended to utilities to mininize stress corrosion cracking of discs?
I'V.
Identify the impurities known to cause cracking in the 1 ow pressure turbines, and their sources. Discuss 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 :eposition of these impurities that tan lead to their conc~ntraticn in certain areas of keyways, and bores.
V.
What role.does the refluxing action in the stea~ s:paratio~ portion of.
the steam generator have on scrubbing corrosive inturitie~ 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:
- 1.
Pumping moisture separator condensate to cor.de:ser?
- 2.
Periodically moving point of condensation tc ~~event localizec buildup of corrosive impurities?
v I I. *Describe f abri ca ti on and heat trea t"'lent sequer.:: f~r discs, including the.nnal exposure during shrinking operations.
VIII. Discuss the effects of any local residual stresses on the cracking mechanism.
--**.