ML19257A957
| ML19257A957 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 12/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Crouse R TOLEDO EDISON CO. |
| References | |
| NUDOCS 8001090497 | |
| Download: ML19257A957 (1) | |
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NUCLEAR REGULATORY COMMISSION g
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799 ROOSEVELT ROAD GLEN ELLYN,lLLINOIS 60137 Docket No. 50-346 Toledo Edison Company ATTN:
Mr. Richard P. Crouse Vice President Energy Supply Edison Plaza 300 Madison Avenue Toledo, OH 43652 Gentlemen:
This Informatinn Notice is provided as an early notification of a possibly significant matter.
It is expecte d that recipients will review the Information for possible applicability to their facilities. No specific action or response is requested at this time.
If NRC evaluations so indicate, further licensee accions may be requested or required.
If you have questions regarding this matter, please contact :'e Director of the appropriate NRC Regional Office.
Sincerely, JamesG.Ke$ die!n_-
Anon r
Director
Enclosure:
IE Information Notice No. 79-37 cc w/ encl:
Mr. T. Murray, Station Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission Helen W. Evans, State of Ohio 1830 056 80010904-7[
UNITED STATES ISINS NO.
6870 NUCLEAR REGULATORY LOMMISSION Accession No.
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
20555 December ;8, 1979 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS Description of Circumstances:
An anonymous letter was received by the 9irector of the Office of Inspection and Enforcement, on November 17, 1979 which alleged possible violation of Part 10 CrR 50.55e and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Westinghouse 1800 rpm low pressure turbine discs.
Westinghouse had made a presentation on the turbine disc cracking to electrir, utility executives on October 30, 1979.
Telephone discussions between the NRC staff and Westinghouse's lurbine 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 sito 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 overhaal 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.
Ultrasonic measurements 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, 1079 regarding the current field inspection program that included a list of nuclear pcwer 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 Poi the plants return to power.
Point Be with a small crack in the No. 2 disc DUPLICATE DOCUMENT Westinghouse indicated that the obser during 28 additional months of turbin the turbine inspection results and an Entire document previously entered into system under:
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