ML19294A795
| ML19294A795 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/01/1979 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 7903220188 | |
| Download: ML19294A795 (2) | |
Text
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T E, w E._.:., c t. VALLEY AUTHORITY f,
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500C Chestnut Street Tower II
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Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLAh7 UNITS 1 AND 2 - METAL SHAVINGS IN VALVE OPERATORS -
NCR 1354 - FIRST INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector M. Gouge on January 5, 1979. Encit.ed is our first interir report.
We expect to submit our next report by February 28, 1979.
If you have any questions concerning this matter, please get in touch with M. R. Wisenburg at FTS 654-2581.
Very truly yours, E
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,i v'J. E. Gilleland Assistant Manager of Power Enclosure cc:
Mr. John G. Davis, Acting Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 r/903220/ 3S ggg s.
,s.uL O'. '.
An Equat opportunity Empioyet
'hCLOSURE SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 METAL SHAVINGS IN VALVE OPERATORS NCR 1354 FIRST INTERIM REPORT Description of Deficiency The deficiency is in the hydraulic operators of the discharge pressure control valves of the motor driven auxiliary feedwater pumps; valves 1-PCV-3-122, 1-PCV-3-132, 2-PCV-3-122, and 2-PCV-3-132.
Each valve operator has a separate self contained hydraulic system.
The valves, complete with operators, were procured from Mason-Neilan, who obtained the operators from M.E.A.,
Incorporated, 2600 American Lane, Elk Grove Village, Illinois 60007.
Apparently, the deficiency has two elements, either or both of which may have caused the two failures to date, or, if not corrected, could have resulted in failures at a later date.
One element is that the hydraulic systems as received at the site contained metal shavings, apparently from the tapping of threaded holes in the systems valving manifolds. The shavings were found in the operating cylinders and filters, and so could be present in most of the components of the systems.
The other element is in a fail-safe transfer feature actuated by a push-pull knob which can be inadvertently positioned in a mid position.
Operation of the manual pump (on the operator) with the knob in the mid position, possibly in conjunction with malfunctions caused by the metal shavings, permitted overpressurization of the hydraulic cylinder to the point where failure of the cylinder anchoring bolts occurred.
This malfunction occurred before preoperational testing and affected two of the four operators at Sequoyah' Nuclear Plant.
Safety Implications '.
If the deficiency had not been detected and corrected, one or more trains of the auxiliary feedwater system could have been rendered inoperable at any time during plant operation.
Since the auxiliary feedwater system is an essential safety system, the deficiency would have jeopardized the health and safety of the public.
Similar operators are installed in the corresponding system at Watts Bar Nuclear Plant, and it is possible that similar deficiencies exist in operators supplied to other utilities' nuclear plants.
Corrective Actions The metal shavings are being removed f rom all valve operators before preoperational testing of the respective auxiliary feedwater trains. The corrective action for the cylinder overpressurization problem has not yet been decided upon and will be provided in a future report.
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