ML19211C680
| ML19211C680 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/31/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Andognini G BOSTON EDISON CO. |
| References | |
| NUDOCS 8001140191 | |
| Download: ML19211C680 (1) | |
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~Yfo UNITED STATES 8
NUCLEAR REGULATORY COMMISSION o
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REGION I
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631 PARK AVENUE Os
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KING OF PRUSSIA. PF.NNSYLVANIA 19406 Docket No. 50-293 1N Boston Edison Company M/C Nuclear ATTN:
Mr.
. Carl Andognini, Manager Nuclear Operations Department 800 Boylston Street Boston, Massachusetts 02199 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
!icensee actions may be.equested or required.
If you have questions regarding this matter, please contact this office.
Sincerely, kl AU a
,,J Boyce H. Gr1 r 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/encls:
P. J. McGuire, Pilgrim Station Manager 1742 281 8 0 01140 /9 / g
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 on the inlet side on the disc bore area where no cracks had been previcusly observed.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than the keyway cracks four.1 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 NPC 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 observed.
Inspec+'
disc cracks at Surry Unit 2, Point Beach and Zion Unit 1.
All units except Point the plants return to power.
Point Beach DUPLICATE DOCUMENT with a small crack in the No. 2 disc of i Westinghouse indicated that the observed Entire document previously during 28 additional months of turbine o entered into system under:
the turbine inspection results and analy
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