ML20138B720

Final Significant Deficiency Rept SD 414/85-10 Re Failure of Hydrogen Skimmer Fan Motors Supplied by Joy Mfg Co.Initially Reported on 850626.Cause Undetermined.Fan Motors Reassembled,Retested & Reinstalled

ML20138B720
Person / Time
Site:	Catawba
Issue date:	11/22/1985
From:	Tucker H DUKE POWER CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
SD-414-85-10, NUDOCS 8512120370
Download: ML20138B720 (3)

Text

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D-DUKE POWER GOMPANY P.O. HOK 33180 I CHARLOTTE, N.O. 28242 HALB. TUCKER TELEPitONE 4 " " * * "

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- November 22, 1985 Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street,_NW, Suite 2900 Atlanta, Georgia 30323 Re: Catawba Nuclear Station, Unit 2 Docket No. 50-414 Significant Deficiency No. 414/85-10

Dear Dr. Grace:

Please find attached our final report on the subject deficiency concerning Hydrogen Skimmer Fan Motor failures. This item is now ready for NRC review.

Very truly yours, BLJ 4PL Hal B. Tucker LTP: sib j Attachment cc: Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 INP0 Records Center Suite 1500 1100 Circle 75 Parkway ,

Atlanta, Georgia 30339 NRC Resident Inspector Catawba Nuclear Station l

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r Duke Power Company Catawba Nuclear Station Final Report Report Number: SD 414/85-10 l Report Date: November 22, 1985 Facility: Catawba Nuclear Station Unit 2 Identification of Deficiency:

Hydrogen Skimmer Fan HSF-2A motor failed May 30, 1985 generating Nonconformance Report No. 19720. The second fan motor, HSF-2B, failed June 24, 1985 generating Nonconfor-mance Report No. 19781. The fan failures occurred after approximately 2h hours of operation. The potential for a defect in a basic component was identified June 25, 1985.

Initial Report:

On June 26, 1985, Mr. C.W. Burger, NRC Region II, Atlanta, Georgia, was notified by telephone of the deficiency by L.M. Coggins, T.L. Utterback, R.R. Weidler and C.A.

Driggers of Duke Power Company, Charlotte, NC 28242.

Component and/or Supplier:

The Hydrogen Skimmer Fans were supplied to Duke Power Company by Joy Manufacturing Company, New Philadelphia, Ohio. The fan assembly was designed and fabricated by Zurn, Kalamazoo, Michigan and the motor is a Reliance Electric, Cleveland, Ohio product.

Description of Deficiency:

Both incidents involved motor bearing failure. Fan HSF-2A shaft end or rear bearing failed. Fan HSF-2B opposite end or front bearing failed. There is evidence of bear-ing operation at high temperature in both cases. Both bearing failures resulted in fan wheel and housing damage. Both motors experienced severe shock loads resulting in bent shafts and snapped mounting feet.

Analysis of Safety Implications:

Loss of fan function would prevent post-accident hydrogen from being scavenged in  !

dead-ended lower containment compartments (reference FSAR paragraph 9.4.10).

Prior to failure, Unit 2 equipment received a motor performance test at Reliance Electric, a fan performance test at Joy Manufacturing Company and was monitored by Duke Power Company during startup. There was no evidence from these tests that would have led to predicting the failures.

Similar equipment is used in the Unit i upper containment. Technical Specification quarterly periodic test duration (15 minutes) does not allow 'this fan-motor to stabilize at operating temperature. Therefore, a problem would not likely show up unless run time is extended.

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Page 2 Corrective Action:

In order to evaluate the failures experienced, Joy and Reliance technical representa-tives directed disassembly of the second fan-motor on site' June 27 and 28, 1985.

Failed motors were reassembled at Reliance to check shaft and housing fit. Failed bearings were evaluated by NSK Corporation, the original Supplier. The cause of failure'cannot be exactly determined.

Unit 2 equipment was repaired using two spare motors available on site. Repaired fan-motors were run for an extended period of time while monitoring critical z

parameters. After successful completion of testing, one motor was disassembled, inspected, bearings removed and evaluated by NTN (Supplier). The motor was then reassembled and retested. There was no abnormal bearing wear detected. Fan-motor testing confirmed normal motor winding and bearing temperature rises. Repaired fan-motors have been reinstalled. Startup testing and balancing have been completed.

Unit 1 equipment was retested by June 29, 1985 to Duke / Vendor's satisfaction establishing operability. Unit 1 equipment was run for an extended period of time fully instrumented for bearing temperature, vibration, electrical charac-teristics, etc.

In conclusion, the Unit 1 equipment and repaired Unit 2 equipment have successfully demonstrated normal operating characteristics and have developed sufficient run time to consider them suitable for service.

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