ML19211C960
| ML19211C960 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 12/28/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8001160055 | |
| Download: ML19211C960 (1) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION CENTRAL FILES
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REGION.V 611 RY AN PLAZA oRIVE. SUITE 1C00 POR:HQ
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,I ARLINGTCN TEXAS 75012 LPOR 7s g
,e Dece=ber 23, 1979 NSIC Docket No.30-285 C=aha Public Power District ATTN:
W. C. Jones, Division Manager -
Production Operaticus 1623 Harney Street C=aha, Nebraska 68102 Gentle =en:
This II Infor=ation Notice is provided as an early notification of a possibly significant =atter.
It is expected that racipients will review the infor=ation for possible applicability to their facilities.
No specific action or response is requested at this ti=e.
If NRC evaluations so indicate, further licensee actions =ay be requested or required.
If you have questions regarding this
=atter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, i
s Karl V. Seyfric Director Enc 1vsures:
1.
II Infor=ation Notice No. 79-37 2.
List of Recently Issued IE Info m tion Notices cc:
S. C. Stevens, Manager Fort Calhoun Station Post Office Sox 98 Fort Calhoun, Nebraska 68102 1756 142 0 5~S' 80u1100 9
UNITED STATES ISINS NO.:
6870 NUCLEAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
20555 mon D
December 28, 1979 O
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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 itress 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-l mented in the field.
The Office of Inspection and Enforcement was also notified l
on November 20, 1979 that during the current overhaul of Commonwealth Edison's Zion Unit 1 LP turbine, ultrasonic examination revealed embedded cracks located j
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 l
bore cracks have been metallurgically examined and preliminary findings show them not to be typical of classical stress corrosion cracking observed in the keyways.
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The p obable cracking mechanism and impact on disc integrity is being further j
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 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, 1979 with a small crac Westinghouse indi lysis by during 28 additio
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itical dimensions is evaluating the turbine inspe DUPLICATE DOCUMENT Entire document previously 4}
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