ML19290E711
| ML19290E711 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Burstein S WISCONSIN ELECTRIC POWER CO. |
| References | |
| NUDOCS 8003140430 | |
| Download: ML19290E711 (3) | |
Text
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UNITED STATES y ;,3.c ( g y
^ g NUCLEAR REGULATORY COMMISSION C
W ASHING TON, D. C. 20555
/
February 25, 1980 Docket No. 50-266 Mr. Sol Burstein Executive Vice President Wisconsin Electric Conpany 231 West Michigan Street Milwaukee. Wisconsin 53201
Dear Mr. Burstein:
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 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 I 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 !ight of this information, we requested that you provide an analysis of tha keyway crack observed in disc number 2 of LP turbine number 1 before you returned Unit No. I to power approximately December 22, 1979.
In our letter of December 27, 1979 (A. Schwencer to S. Burstein) we requested additional information to enable us to continue our review of this matter. We now believe that more detailed information is required for our review. Therefore, we request that you provide and address the safety significance of the information listed in Enclosure 2 of this letter.
If you desire, you may incorporate your responses to our December 27, 1979 letter and submit all responses within 20 days of the date of this letter.
3h.1 8 003; d o
Mr. Sol Burstein 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 adcress the generic aspects of this problem and to coordinate your responses through an owner's group.
- ncerely, Darrell G. Ef e'nhut, Acting Director Division of perating Reactors
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. Sol Burstein Wisconsin Electric Power Company February 25, 1980 cc: Mr. Bruce Churchill, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.
Washington, D. C.
20036 Document Department University of Wisconsin Stevens Point Library Stevens Point, Wisconsin 54481 Mr. Glenn A. Reed, Manager Nuclear Operations Wisconsin Electric Power Company Point Beach Nuclear Plant 6610 Nuclear Road Two Rivers, Wisconsin 54241
Enc b re 1 UNIll0 MALES ISINS NO.:
6870 NUCLEAR REGULAIORY CC+'. MISSION Accession No.:
Off T'T OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
20555 Decer.ber 28, PJ79 IE Information Notice No. 79-37
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CRACKING Ill LOW PRESSURE TURBINE DISCS D,escription of Circut.atances:
An anony:cus letter was received by the Director of the Office of Inspection and Enfc rcee.nt, on Noverber 17, 1979 which alleged possible violation of Part 10 CFR 50.S5e an f/or 10 CFR 21 Regulations concerning reportability. of recently discovered stress corrosion t. ricking in Ucstinghouse 1800 rpm low pressure turbine discs.
Westinghause lad rade a presentation on the turbine disc cracking to electric utility executives on October 30, 1979.
Talephone disemsions between the NRC staff and Westinghouse's Turbine Division o n Nr. e.. '.e r /0, 1979 established that cracking, attributed to stress corrosion f.2na n u, l.2d Sc un f&nd in the k yway areas of several LP turbine discs at
.,x rating plants and t.at inservice inspection techniques (i.e., in situ ultra-sanic cxc:.inatica) for crack detection have been developed and are being imple-
..:nted in the field.
The Office of Inspection and Enforcement was also notified cn Nave -b;r 20, 199 that during *he current overhaul of Corsonwealth Edison's lion Unit 1 LP turbine, ultrasonic examination revealed embedded cracks located ca t!.e irlet side on the disc bore area where no cracks had been previcusly cbser.ed.
Ultr =senic teasurenants indicate this disc bore cracking is of greater depth than the Ley-ay cracks found to date.
According to Westinghouse, these bore cracks have been netallurgically examined and preliminary findings show them not to be typical of classical stress corrosion cracking observed in the keyways.
The pt c':eble crading. achanism and irrpact on disc integrity is being further evaluated by WestingMse.
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 tissile cvaluation, inspection techniques and plant inspection priorities.
In response to the staf fs' request, Westinghouse provided the staff an updated report on Dececber 21, 1979 regarding the current field inspection program that included a list of nuclear power plants already inspected, recom-canded inspection schedules and pertinent infor.r.ation 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 end Zion Unit 1.
All units except Point Seach Unit 2 will make repairs before P c^
the plants return to power.
Point N
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with a small crack in the No. 2 di Westin; house indicated that the ob DUPLICATE DOCUMENT during 28 additional conths of tur the turbine inspection results and Entire document previously entered into system under:
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