ML19211C120
| ML19211C120 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/28/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Arenal A SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 8001100101 | |
| Download: ML19211C120 (1) | |
Text
- pa ascoq'o, UNITED STATES
! \\*T.,',
NUCLEAR REGULATORY COMMISSION lb g
nE REGION V e
o 1990 N. CALIFORNI A BOULEVARD e
SUITE 202, WALNUT CREE K PLAZA
+,..e WALNUT CREEK, CALIFORNIA 94596 December 28, 1979 Docket Nos. 50-206, 50-361, 50-362 Southern California Edison Company P. O. Box 800 2244 dalnut Grove Avenue Rosemead, California 91770 Attention: Mr. A. Arenal, Vice President Advanced Engineering 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 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 the Director of the appropriate NRC Regional Office.
Sincerely, hb,~,d0-R. H. Engelken Director
Enclosures:
1.
IE Information Notice No. 79-37 2.
List of Recently Issued IE Information Notices 7}g }gQ cc w/ enclosures:
J. M. Curran, SCE J. T. Head, SCE J. H. Drake, SCE 8 001100 lO l
UNITED STATES ISINS N0.: 6870 NUCLEAR REGULATORY COMMISSION Accession No.:
0FFICE OF INSPECTION AND EllFORCEMEflT 7910250525 WASHINGTON, D.C.
20555 December 28, 1979 IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS Description of Circunstances:
An anonymous letter was received by the Director of the Office of Inspection and Enforcenent, on November 17, 1979 which alleged possible violation of Part 10 CFR 50.55e and/or 10 CFR 21 Reaulations 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 crackina to electric utility executives on October 30, 1979.
Telephone discussions betwaen the NRC staff and Westinahouse's Turbine Division on November 20, 1979 established that crackina, attributed to stress corrosion phenomena, had been found in the keyway areas of several LP turbine discs at operatinq 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. Ultrasonic measurements indicate this disc bore cracking is of greater depth than the keyway cracks found to date.
Accordina to Westinghouse, these bore cracks have been metallurgically examined and preliminary findinas show them not to be typical of classical stress corrosion cracking observed in the keyways.
The probable cracking mechanism and impact on disc intege<t< is being further evaluated by Westinghouse.
A meetina 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 resoonse to the staffs' request, Westinghouse provided the staff an updated report on December 21, 1979 reaardina the current field inspection oroaram 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 Beach Unit 2 will make repairs before the plants return to power. Point Beach returned to power on December 23 with a snall crack in the No. 2 disc o' Westinghouse indicated that the observ DUPLICATE DOCUMENT during 28 additional months of turbine the turbine inspection results and ana Entire document previously entered into system under:
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~79/gMeS95 nNO No. of pages: