ML19257A989
| ML19257A989 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 12/31/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Dunn C DUQUESNE LIGHT CO. |
| References | |
| NUDOCS 8001140205 | |
| Download: ML19257A989 (1) | |
Text
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'o UNITED STATES 7E 8
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KING OF PRUSSIA, PENNSYLVANIA 19406 Docket No. 50-334 DEC 3 13979 Duquesne Light Company ATTN:
Mr. C. N. Dunn Vice President Operations Division 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the infor-mation for possible applicability to their facilities.
No specific action or response is requested at this time.
If NRC evaluations so indicate, further licensee actions may be requested or required.
If you have questions regarding this matter, please contact this office.
Sincerely, YL UL
, A yce H. Grier Director
Enclosures:
1.
IE Information Notice No. 79-37 with attachments 2.
List of Recently Issued IE Information Notices CONTACT:
L. E. Tripp (215-337-5282) cc w/encis:
F. Bissert, Technical Assistant Nuclear R. Washabaugh, QA Manager J. Werling, Station Superintendent G. Moore, General Superintendent, Power Stations Department J. J. Carey, Nuclear Technical Assistant R. Martin, Nuclear Engineer 1745 ;42 5 0 0110 2 CS Sk
ENCLOSURE 1 UNITED STATES ISINS NO.:
6870 NUCLEAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
20555 IE Information Notice No. 79-37 Date:
December 31, 1979 Page 1 of 2 CRACKING IN LOW PRESSURE TURBINE DISCS Description 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 50.55(e) 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 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 the inlet side on the disc bore area where no cracks had been previously oc observed.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than the keyway cracks found to date.
According to Westingbouse, 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 alret.dy 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 Beac and Zion Unit 1.
All units except Poin the plants return to power.
Point Beac with a small crack in the No. 2 disc of DUPLICATE DOCUMENT Westinghouse indicated that the observe during 28 additional months of turbine Entire document previously the turbine inspection results and anal entered into system under:
ANO i N9***
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