ML19290E755
| ML19290E755 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 02/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Peoples D COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8003140480 | |
| Download: ML19290E755 (3) | |
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o UNITED STATES h,}\\*f) #. ( (',i E
NUCLEAR REGULATORY COMMISSION
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Februa ry 25, 1980 Docket No.
50-295 Mr. D. Louis Peoples Director of Nuclear Licensing Commonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Peoples:
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 Infs nation 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 interin correspondence with the staff.
On the basis of information provided by Westinghouse and recent indications from turbine dise 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.
It is my understanding that keyway cracks have been identified in discs in low pressure turbines at Zion Unit 1 and you are in the process of making the necessary repairs. We request that the results of your turbine inspections, a description of corrective actions being taken, and justification that this action is sufficient to permit returning this unit to operation, be reported to us prior to resuming operation. We also request that you provide the infor-mation listed in Enclosure 2 to this letter and your assessment of the safety significance of your responses. Please contact us if you have any questions concerning these requests.
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Mr. D. Louis Peoples
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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.
Sincerely, b
Da
. ~ sen ut, Acting Director Division o 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. D. '.o:ds Peoples Conmonwealth Edison Company February 25, 1980 cc: Robert J. Vollen, Esquire 109 Ntrth Dearborn Street Chicago, Illinois 60602 Dr. Cecil Lue-Hing Director of Research and Development Metro;olitan Sanitary District of Greater Chicago 100 East Erie Street Chicago, Illinois 60611 ZiorrEenton Public Library District 2600 Encats Avenue Zion, Illinois 60099 Mr. Phillip P. Steptoe Isham, Lincoln and Beale Counselors at Law One First National Plaza 42nd Floor Chicago, Illinois 60603 Susan.'i. Sekuler, Esquire Assis ant Attorney General Envirencettal Control Division 128 West P.andol ph Street, Suite 2315 Chicago, Illinois 60601
Encloure 1 e
UNITED STATES ISINS NO.:
6870 NUCl. EAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
20555 December 28, 1979 IE Information Notice No. 79-37 CEACKING IN LOW PRESSURE TURBINE DISCS Description of Circtmstances:
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 S0.55e and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Westinghouse 1800 rpm low pressure turbine discs.
Westinghouse had cade a presentation on the turbine disc cracking to electric utility executives on October 30, 1979.
Telephone discussions between the NRC staff and Westinghouse's Turbine Division on November 20, 1979 established that cracking, attributed to stress corrosion phenomena, had been found in the keyway areas of several LP turbine discs at operating plants and that inservice inspection techniques (i.e., in situ ultra-sonic examination) for crack detection have been developed and are being imple-mented in the field.
The Office of Inspection and Enforcement was also notified on November 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 side on the disc bore area where no cracks had been previously observed.
Ultrasenic reasurements indicate this disc bore cracking is of greater depth than the keyway cracks found to date.
According to Westinghouse, 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 being further evaluated by Westinghouse.
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 missile evaluation, inspection techniques and plant inspection priorities.
In response to the staffs' request, Westinghouse 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 cbserved.
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 make repairs before the plants return to power.
Poin rned to er on December 23, 1979 with a small crack in the No. 2 di Westinghouse indicated that the c s
during 78 additional conths of tur DUPLICATE DOCUMENT she turbine inspection results an Entire document previously entered into system under:
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ANO c-No. of pages:
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