ML19257A958
| ML19257A958 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/28/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Bryan J UNION ELECTRIC CO. |
| References | |
| NUDOCS 8001090502 | |
| Download: ML19257A958 (1) | |
Text
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UNITED STATES 8
NUCLEAR REGULATORY COMMISSION n
.E REGION 111 o,,
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799 ROOSEVELT ROAD
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GLEN E LLYN, ILLINOIS 60137 Docket No. 50-483 I
Docket No. 50-486 Union Elect.ic Company ATTN:
Mr. John K. Bryan Vir President - Nuclear P. O. r,ox 149 St. Louis, MO 63166 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the Information for possible applicability to their facilities. No specific actie4 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 the Director of the appropriate NRC Regional Office.
Sincerely, y
i
. James G. Kei ler Director
Enclosure:
IE Information Notice No. 79-37 cc w/ encl:
Mr. W. 11. Webe r, Manager,
Nuclear Construction Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Region I & IV Ms. K. Drey Mr. Ronald Fluegge, Utility Division, Missouri Public Service Commission i
80010905o2.
UNITED STATES ISINS NO.:
6870 NUCLEAR REGULATORY COMMISSION Accession No.-
0FFICE OF INSPECTION AND ENFCRCEMENT 7910250525 WASHINGTON, D.C.
20555 December 28, 1979 IE Information Notice No. 79-37 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 50.55e 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 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 ultrs-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 turuine, ultrasonic examination revealed embedded cracks located on the inlet side on the disc bore area where r.o 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 classica: stress corrosion cracking observed in the keyways.
The probable cracking mechanism ar.d 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 regarding t'e current field inspection staff an updated report on December 21, 1979 n
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 the plants retura to power.
Point B with a small crack in the No. 2 disc Westinghouse indicated that the obse during 28 additional munths of turbi DUPLICATE DOCUMENT the turbine inspection results and an Entire document previously 87^05~
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