ML20081J136
| ML20081J136 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 11/04/1983 |
| From: | Dixon D GENERAL ELECTRIC CO. |
| To: | Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| REF-PT21-83-043-000 PT21-83-043-000, PT21-83-43, NUDOCS 8311080320 | |
| Download: ML20081J136 (6) | |
Text
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s GEN ER AL h ELECTRIC
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BUSINESS GENERAL ELECTRIC COMPANY, 41 WooDFoRD AVENUE, PLAINVILLE, CCNN. 06062 Phone (203) 747 7 O P E R ATlO N S November 4, 1983
-Mr. Richard C. DeYoung Director of Office of Inspections U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Washington, D.C.
20555
Dear Mr. DeYoung:
The Distribution Equipment Engineering and Manufacturing Operation of the General Electric Company has determined on this date that a reportable defect exists on certain AKR-30 and AKR-50 Low-Voltage Power Circuit Breakers manufactJred between mid-1976 and December,1978. The following is the text of UJr notification for your use as neCessary:
It has come to our attention that, in a limited number of instances, a bearing in AKR-30 and AKR-50 Low-Voltage Power Circuit Breakers may become loose as a result of the mounting hole having been manufactured slightly larger than specified.
If this bearing comes completely out, it may not be possible to close the circuit breakec.
The only known instance of this tearing becoming loose occurred at the Louisiana Power and Light Company's Waterford III facility. The circuit breakers at that site have already been modified to prevent the bearing from moving.
The General Electric Company proposes to correct this potential problem in all Nuclear Class lE applications. The correction will consist of installing a retaining plate to prevent the bearing from moving, even if the mounting hole is oversized. We are presently reviewing our files to determine which Nuclear facilities have these subject breakers, and we will soon De contacting the affected sites to arrange for the installation of the retaining plates at a mutually convenient time.
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GENER AL O iticiaic Mr. R. C. DeYoung November 4, 1983 Attached to this notification is a copy of the information related to this potential defect which has been given to the Waterford III facility.
If you require any further information, please contact me.
VeryTrulyYourh k)Iub bk2 Davic J Dixo, Manager Qualit Assurance cit / Attach. (2316P) cc:
V. D. Thomas - US NRC - Wash., D.C.
E. N. DeVault L. C. Peterson W. J. Heerlein J. P. Werner M. B. Fornwalt J. Jerse - PBI - Vega Baja, P.R.
J. Fuentes-PBI - Vega Baja, P.R.
J. Grillo - Waterford III - Taft, La.
G. G. Sherwood, Mgr.-Nuclear Safety & Licensing Oper.
GE Nuclear Power Systems Division 175 Curtner Avenue San Jose, California 95125
l GENER AL h ELECTRIC
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EQUIPMENT BUSINESS GENERAL ELECTRIC COMPANY, 41 wooDFoRD AVENUE, PLAINVILLE. CONN. 06062 Phone (203; 747 7 OPER ATlO N S October 12, 1983 Mr. John Grillo Waterford SES Unit III EBASCO Services, Inc.
Highway 18 Taft, Louisiana 70066 (35 Miles West of New Orleans)
Dear John:
At our request, you returned an AXR-4A-50 Low Voltage Power Circuit Breaker, Serial No. AK 06665, for our analysis to detemine the cause of the loose bearing on the mechanism cam shaft. This circuit breaker was inspected and analyzed in our factory on September 30, 1983, with the following conclusions:
The needle bearing in question, Part No.192A9653P7, was loose on the cam shaft and could be moved with moderate finger pressure, e
The bearing inside diameter and outside diameter were found to be in accordance with their nominal reference dimensions.
The hole in the side frame into which the needle bearing is pressed was determined to be.003" larger than the maximum diameter specified.
The outer race of the bearing in question did not have any score marks on it, raising the question as to whether it was fully pressed in at the time of assembly.
This information was discussed with the bearing manufacturer, Torrington Bearing Company, and they agreed with our conclusion that the bearing worked out of its mounting hole because the mounting hole is i
oversized and does not provide the friction necessary to retain the I
bearing as intended.
SENERAL $ ELECTRIC Mr. John Grillo October 12, 1983 A retaining plate, which can easily be added to the circuit breakers, is being designed to insure that the bearing is retained properly, even when the hole is oversized. This retaining plate will be added to all AKR-30 and AKR-50 Breakers at the Waterford III installation.
If you have any questions, please feel free to contact me.
Very Truly Yours, f
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Davi/J.Dixon, Manager Quality Assurance cc:
J. P. Werner P. M. Piqueira M. B. Fornwalt S. St. Jonn cit (2268P) l l
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0 DISTRIBUTION 5"i EQUIPMENT DIVISION INSTALLATION PROCEDURE FOR BEARING RETAINER PLATE ON ELECTRICALLY OPERATED TYPE AKR-30/50 LOW VOLTAGE POWER CIRCUIT BREAKERS.
TAB
' NO.
175 9.17 SERVICE ADVICE cm : ni s..
The following procedure ai> plies to electrically operated type AKR-30/50 Leu Voltage Power circuit breakers and is intended as a rework quide for the installation of a bearing retainer plate.
AKR-30/50 type breakers which are electrically operated have bearings supporting the charging shaft mounted on the mechanism side frames.
These bearings are pressed in the side frames and. if the bearing mounting hole is oversized. the one on the left side frame may work itself out of the frame along the charging shaft, which could possibly result in the breaker failing to close upon command.
l t
INSTRUCTIONS a)
Remove molded plastic escutcheon and/or metal escutcheon plate 1
l cn front of breaker.
l b)
Remove "F" and "G"
switch mounting bracket screws on right mechanism side frame.
c)
Install bearing retainer plate (P/N 286A8784P1).
Place open end of retainer plate inside of mechanism assembly on left side of charging shaft and swing it towards the front of the breaker.
PREPARED BY ISSUED BY DATE SUPERSEDES PAGE ISSUE DATED J. A. FERREIRA P. M. PIQUEIRA 10/12/83 NEW 1 of 2
DISTRIBUTION 5t'8HCT EQUIPMENT DIVISION INSTALLATION PROCEDURE FOR BEARING RETAINER PLATE ON ELECTRICALLY OPERATED TYPE AKR-30/50 LOW VOLTAGE POWER CIRCUIT BREAKERS.
TAB NO.
175 9.17 SERVICE ADVICE
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Part will rest at this point in a position that lines up alnost with the mounting hole on the left side frame.
d)
Align part with mounting hole on left side frame and secure by using 3/8 16 x 3/4 bolt (P/N N22P25012B13) and lock washer (P/N N405P13C).
Torque to 200 inch pounds.
e)
Mount back
- F" and "G"
switch bracket, metal escutcheon and molded plastic escutcheon.
f)
Record:
Breaker Serial Number Rework Site Rework Done By Date (0846a)
PREPARED BY ISSUED BY DATE SUPERSEDES PAGE ISSUE DATED J. A. FERREIRA P. M. PIQUEIRA 10/12/83 NEW 2 of 2
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