ML20128G209

Responds to NRC 850521 Request for Supplemental Info Re Insp Repts 50-259/84-52,50-260/84-52 & 50-296/84-52.Corrective Actions:Mechanical Maint Instruction 87 Revised to Ensure Insp Requirements Clearly Identified

ML20128G209
Person / Time
Site:	Browns Ferry
Issue date:	06/20/1985
From:	Domer J TENNESSEE VALLEY AUTHORITY
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20128G213	List: ML20128G209 ML20128G228
References
NUDOCS 8507090104
Download: ML20128G209 (5)

Text

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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II June 20, 1985 5 JC 2'l ^ 0 : 33 U.S. Nuclear Regulatory Consission Region II ATTN: Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323

Dear Dr. Grace:

Enclosed is our response to R. D. Walker's letter to H. G. Parris dated May 21, 1985 requesting a supplemental response for Inspection Report 84-52 for our Browns Ferry Nuclear Plant.

If you have any questions, please get in touch with R. E. Alsup at FTS 858-2725.

To the best of my knowledge, I declare the statements contained herein are complete and true.

Very truly yours, TENNESSEE VALLEY AUTHORITY OktbL J. A. Domer, Chief Nuclear Licensing Branch Enclosure cc: Mr. James Taylor, Director (Enclosure)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Consission Washington, D.C. 20555 i

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l An Equal Opportunity Employer

i ENCLOSURE

- SUPPLEMENTAL RESPONSE NRC INSPECTION REPORT NOS.

50-25 9/ 84-52, 50-260/ 84-52, AND 50-296/ 84-52 ROGER D. WALIER'S LETTER TO H. G. PARRIS DATED MAY 21, 19 85 Item 1 How did the incorrect verification of pinion gear installation occur, and was it attributable to inadequate training or procedures?

Response

During testing of FCV 74-12 on unit 3, the valve f ailed to pass timing requirement s, and a maintenance request was initiated to investigate the **

problem. The drive motor was removed, and a loose setscrew used to secure the motor pinion gear to the shaf t was discovered. The setscrew was tightened, and the valve reassembled. The pinion gear was not removed from the motor shaf t during the maintenance.

Maintenance activities associated with Limitorque operators are controlled by Mechanical Maintenance Instruction (MMI) 87 (Corrective and Preventative Maintenance of Limitorque Operators). To verify motor pinion gear orientation, an exploded view of the operator (attached) is provided in the instruction. The correct pinion gear orientation is, as shown, dependent on the size and model of the Limitorque operator involved. The craftsmen involved with verifying orientation in this case misinterpreted the sketch and, consequently, verified the orientation of the gear incorrectly.

The personnel involved had received training on Limitorque operators and, therefore, would have been expected to correctly perform this task. We consider the event largely personnel error, and the craf tsmen and foreman were assessed time off without pay.

Item 2 Are all Limitorque valve operators inspected by these two individuals in response to the NRC request being reinspected?

Resnonse A review of maintenance records indicated that this is the only valve inspection for pinion gear orientation performed by these craf tsmen.

Item 3 What additional corrective actions will be, or have been taken to ensure that your initial response to the Notice of Violation is adequately impl emented ?

A

P2ga 2 Resnonse NNI-87 is being revised to ensure that inspection requirements are clearly identified. The inspection program for Limitorque operators on emergency core cooling system valves has been increased from a 20 percent sample to a full inspection. No additional reverse sears have been found to date. In addition, a comprehensive three-day training course utilizing several different Limitorque operators has been developed by our training organization. This course involves principles of operation and " Rands on" practice on these operators. Feedback from participants indicates a very good course has been developed. Craf tmaen and engineers who are responsible for maintenance activities on Limitorque are receiving this training.

Although not related to the particular problem discussed above, Browns Ferry has purchased two Motor Operator Valve Analysis Test Systems (NOVATS) . This will greatly enhance our diagnostic capability in evaluating valve problems.

Vendor sponsored training on the use of this equipment is proceeding.

Additional Information In regards to the relationship to valve operability and pinion gear setscrew tigh t ne s s, it must be noted that both subject valves had motor pinion sears installed backwards. In this configuration, enough clearance is available for total disengagement of the motor pinion and worm shaf t clutch gear (see attached figure).

If the pinion gear installation is correct, valve operability would only be affected if the setscrew was loose and the key slipped out of the key slot ,

(or the key sheared) . This is an unlikely situation. MMI-87 is being '

revised to ensure the key is kept in position (if loose) by pricking the end of the pinion key.

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ASSDBLY DETAIIS OF LDILTOPQUE OPERATOR FOR FCV 74-12 NOIE: 'lhere are two different orientations required for motor pinion gear orientation. FCV 74-12 utilizes a SMB-1 operator.

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