ML20004F754
| ML20004F754 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 06/05/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8106220281 | |
| Download: ML20004F754 (2) | |
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1 TENNESSEE VALLEY AUTHORITY CH A TTANCCGA. TENN ESS EE 37'01 ~
400 Chestnut Street Tower II
'. e June 5, 1981 SQRD-50-328/81-16 e
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Mr. James P. O'Reilly, Director 2
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Office of Inspection and Enforcement U.S. Nuclear Regulatory Connission 4,,
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- u., neo, 7f Regien II - Suite 3100 C
,g 101 Marietta Street
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Atlanta, Georgia 30303 3
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Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - LIMIT SWITCH ACTUATOR FOR MASCNEILAN AIR-CPERATED VALVES - SQRD-50-328/81 FINAL REPORT The subject deficiency as initially reported to NRC-0IE Inspector R. W. Wright cri January 20,198^ in accordance with 10 CFR 50.55(e) as NCR SQN NEB 8103.
Our interim reports were submitted on February 19 and April 27, 1981. Enclosed is our final report. This report makes clarificaticris to both the description of deficiency and the size valves affec ted. The submittal date of this report was discussed with R. V. Celenjak on June 1, 1981.
If you have any questiens, please got in touch with D. L. Lambert at FTS 857-2581.
Very trul'y yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure-cc: Mr Victor-Stallo, Director- (Enclosure-)
Office of Inspection and Enforcement U.S. Nuclear Regulatory-Commission Washington, DC 20555
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ENCLOSURE SEQUOTAH NUCLEAR PLANT UNIT 2 LIMIT SWITCH ACTUATOR FCR MLSONEILAN AIR-CPERATED VALVES SQRD-50-328/81-16 10 CFR 50.55(e)
FINAL REPORT Description of Defici ncy During the performance of a preoperational test en Sequoyah unit 2, it was discovered that the valve stem on some of the Masoneilan air-operated valves supplied by Westinghouse rotate. This rotatien in some cases resulted in the loss of valve positica indication due to the actuator missing the valve position switches. This rotaticn appears to be a generic condition for Masone11an air-operated isolation valves.
Safety Implications This condition could mault in an operator being supplied with insufficient information on the main control panel,~ thus resulting in the operator taking inappropriate action during normal operations er during an accident. The inappropriate actions could jeopardize the safe operation of the plant.
Additional evaluation of this condition has revealed that, although the stem rotatien could result in the loss of position indicatien, it would not adversely affect the centrol logic of the valves. This less Of indicatien would not be censidered a safety problem since those valves perfor ing safety-related functicns have sufficient redundant features to deter =ine the position of the valves.
Corrective Actions Additional information provided by Masoneilan and Westinghouse has resulted in TVA reconsidering the applicability of' this deficiency' to certain larger valves as well as 3/4" and 1" valves. Westinghouse and Maseneilan investigated the deficiency onsite and determined that the actuator arm rotation is caused by stem rotation. This stem rotation msults from shrinkage of the diaphragm and subsequent loosening of the stem nut.
Westinghouse has recommended that TVA tighten the stem nuts on affected valves. TVA will inspect those Masone11an valves which perform a safety function for sten rotation._ If required, TVA will tighten nuts cc replace the diaphragma.
In addition, valves which are required for normal operations are checked periodically for' position indication under existing surveillance instructicas, and any loss of indication would be-detected during this check.
Any work required en affected valves will be completed before initial criticality.-
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