ML20148F991
| ML20148F991 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 01/21/1988 |
| From: | Counsil W, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-103, TXX-88020, NUDOCS 8801260373 | |
| Download: ML20148F991 (2) | |
Text
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Log # TXX-88020 File # 10110
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1UELECTRIC l
January 21, 1988 w mi m c. cousa Exerwise Vke hendent U. S. Nuclear Regulatory Commission Attn: Document Control Desk l
Washington, D. C.
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SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET N05. 50-445 AND 50-446 CRACKED GEARS IN VALVE OPERATORS SDAR: CP-87-103 (FINAL REPORT)
Gentlemen:
1 On September 11, 1987, we verbally infonned your Mr. H. S. Phillips of a deficiency involving cracked gears in valve operators. Our previous interim reportwasloghedTXX-7079,datedDecember 10, 1987. We have concluded that i
this issue is reportable under the provisions of 10CFR50.55(e) and the required information follows.
DESCRIPTION OF DEFICIENCY Limitorque HBC-3 valve drives that utilize cast bronze sector gears were found to have visible defects and cracks in the web area where they bolt to the steel drive sleeves.
Specifically, Limitorque Model SMB-00 motor operators that are eq;ipped with a Limitorque HBC-3 drive are designed for use on medium and large size butterfly and ball valves.
The HCC-3 drive utilizes a steel worm gear that drives a cast bronze sector gear bolted to a steel drive sleeve which fits around the valve stem The bolts used to hold the bronze sector gear to the steel drive sleeve are 2 inch long, 5/8 inch in diameter, SAE fine thread, socket head cap screws and 5/8 inch nuts equipped with nylon insert type locking devices.
In one case, two of the bronze sector gear bolt holes had visible casting defects with cracks through the defective casting area.
There are a total of ten Limitorque SMB-00 operators with HBC-3 drives in Unit 1.
The cause of the sector gear cracks is an interference between the chamfer on the bolt and the edge of the bolt hole.
The problem is applicable to all safety-related Limitorque HBC valve operators with a cast bronze sector gear.
As a result of our assessment, we have contacted the supplier regarding the potential reportability of this issue pursuant to 10CFR21.
8801260373 880121 ADOCK050g4j5 q
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400 Nonh Olive Street LB8I Dallas Texas 1901
p TXX-88020 January 21, 1988 Dage 2 of 2 SAFETY IMPLICATIONS
-The operability of the ten Unit I active valves which utilize the Lin.: torque HBC-3 drives could have been compromised by the cracked sector gear, preventing the valve from performing the required safety function.
The possible failure of these valves to perform their intended safety function during an accident condition represents a significant deficiency which, were it to remain uncorrected, could have adversely affected safe operation of the plant.
CORRECTIVE ACTIONS in order to correct these deficiencies, all affected valves and replacement parts will be reworked or replaced as a result of our continued evaluation with the supplier.
In order to preclude recurrence of these conditions, restrictions will be documented for future procurement activities involving HBC operators.
We anticipate completion of the above activities by August 11, 1988 for Unit 1.
Unit 2 activities will be conducted in accordance with the general construction schedule.
Very truly yours, bb b W. G. Counsil 3
Sn By:
D. R. Woodlan Supervisor,
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Docket Licensing l
iiAM/grr c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)
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