ML20116K089

Followup Part 21 Rept Re Overcompression of Power Lead Gland Assembly Sealant During Factory Assembly.Procedures Revised to Specify That Only One Coat of Threaded Lubricant Will Be Applied.Proprietary Rept Encl.Rept Withheld

ML20116K089
Person / Time
Site:	Perry, Vermont Yankee, 05000000
Issue date:	03/05/1985
From:	Fox R CONAX CORP. (FORMERLY CONAX BUFFALO CORP.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
Shared Package
ML19269B471	List: ML20116K089
References
REF-PT21-85, REF-PT21-85-231-000 PT21-85-231, PT21-85-231-000, NUDOCS 8505030181
Download: ML20116K089 (3)

Text

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2300 WALDEN AVE.

• BUFFALO, NY 14225 716 8044600 TELEX:91-275 CAME:CONAXC0 Q ACOMCOM*AW March 5,1985 Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, DC 20555 i

Subject:

Corrective Action of Defect Conax Power Lead ("PL") Gland Assemblies Qualified for Nuclear Service

Reference:

1. Conax Notification of Potential Defect 8/31/84 (Attached) l 2. Conax IPS-1233, Orig. (Enclosed)

Gentlemen:

in accordance with Reference No. 1 (attached), Conax has completed

! its evaluation of the potential reported defect of the subject Power Lead l Gland Assemblies. The results are documented in Conax Report IPS-l 1233, " Power Lead (P/L) Gland Assembly- Design Engineering Investigation" (Reference #2, enclosed), as summarized below.

l l Cause:

l

! The primary cause of the reported potential defect was determined to be an "over compression" of the power lead gland sealant during factory assembly, which eventually lead to a reduction in conductor cross sectional area at the conductor-sealant interface, and eventual conductor separation. This "over compression" was determined to have been caused by both the method with which thread lubricant was applied and the tools used to torque the gland midlock cap to the body during factory production.

All threads of the Vermont Yankee assembly component parts were lubricated prior to final assembly by dipping them in a freon /vydax solution (2 coats) . The Perry assemblies were lubricated prior to final assembly by brushing on the freon /vydax solution (1 coat).

Conax has determined that the dipping technique results in a thicker coat of lubricant material as compared to the brushing method, which would reduce thread friction during the torquing assembly process and subsequently transfer more of the applied torque to be translated l

into sealant compression.

( Compounding this process, the torque. wrench used to assemble both the Vermont Yankee and Perry glands indicated applied torque through t a " dial type" indicator gauge. This wrench design would therefore i

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Director March 5,1985 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Page 2 allow torquing in excess of the required production parameters without automatically halting the operation, as would a presettable ratchet type wrench. The torquing operation was therefore not adequately controlled to within the tolerance specified in the factory assembly procedure. When the Vermont Yankee glands were evaluated, there was a strong indication that many of them may have been initially overtorqued during the factory assembly process.

Also, a contributing factor to the cause of the reported possible defect was determined to be the overextended service temperature to which the Vermont Yankee glands were exposed. By attempting to operate their power lead glands at a service temperature of 260 F, rather than the Conax recommended, (and previously qualified) '

service temperature of 150 F, Vermont Yankee had caused the already overcompressed sealants to thermally expand, thereby further contribu-ting to the eventual conductor separation mechanism. I 11 Corrective Action:

All of the Vermont Yankee Power Lead glands were removed from service and returned to Conax.

Forty-one (41) Power Lead Glands were returned to Conax by Perry for evaluation. Based on that evaluation, it was determined that the Perry Power Lead Glands did not contain the same possible defect reported by Vermont Yankee and would therefore be acceptable, provided they were operated at the original required normal operating service temperature (not to exceed 144 F) .

til Preventative Action i Conax will revise all drawings and assembly procedures to specify that one (1) coat of the thread lubricant shall be applied only by the brushing technique and not the dipping methodology. i l Conax will remove all dial indicator type torque wrenches from factory assembly service and will replace them with presettable ratchet type torque wrenches. In addition, Conax will revise all assembly pro-cedures to permit only the use of the ratchet type torque wrench.

For further clarification of our position or any additional information, please contact me directly.

Very truly yours, AX O CORPORATION

' JMZJ6 J f/

Itobert A. Fox President RAF/cas

Director March 5, 1985 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Page 3 cc: Boyce H. Grier, Director, Region 1 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Ave.

King of Prussia, PA 19406 Mr. Richard Pagodin Engineering Support Supervisor Vermont Yankee Nuclear Power Corporation P. O. Box 157 Vernon, VT 05354 Mr. George Hengerly Yankee Atomic Electric Company 1671 Worcester Rd.

Framingham, MA 01701 Mr. Paul Martin General Supervisory Engineer PAQS The Cleveland Electric illuminating Company Perry Nuclear Power Plant, Units 1 and 2 P. O. Box 85 Perry, OH 44081 CONAX BUFFALO CORPORATION: M. W. Connell J. 'E. Adams W. S. Rautio D. P. Jensen W. C. Federick R. E. Duiski R. L. Duroure R. E. Farchmin S. M. Dale G. P. Wittmann Attachment (i)

Enclosure (1)

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=h , =>:4i w.:e.nm. m 3 CONAX CORPORATION.2300 WALDEN AVENUE, BUFFALO, NEW YORK 14225 TEL.716-684-4500 TELEX 275 1

1 August 31, 1984 Director Office of Inspection and Enforcement U.S. N; clear Regulatory Commission Washington, D.C. 20555

Subject:

Notification of a Potential Defect Conax Power Lead (PL) Gland Assemblies Qualified For Nuclear Service Gentlemen: _

Your attention is directed to our telephone communication with your Mr. Harry Kisteo of Regional Office 1 on August 29, 1984 concerning reasonable indica-tion of a defect. A conditioned situation exists which Conax has designated a potential defect.

This formal communication is submitted as timely evloence of our compliance to the requirements of 10 CFR Part 21, Paragraph 21.21, b(2), with the following information being provided to the extent known to date per items i through viii of paragraph 21.21, b(3), of 10 CFR Part 21. .

! I) Reporting Inoividual:

l W. S. Rautio Presioent Conax Buffalo Corporation 2300 Walden Avenue Buffalo, New York 14225 (716) 684-4500

, II) A. Component Identification l Conax Qualified Nuclear Service Power Lead Gland Assemblies l

l Conax Part Numbers: 7092-11000-01, -02, -03, -04 7D92-1.1001-01, -02, -03, -04, -05 N-11150-01 N-lll51-01

-INU10-70

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l B. Facility Identification .

1. Vermont Yankee Nuclear Plant -

Governor Hunt Road Vernon, VT 05354

11. Perry Wclear Power Plant, Units 1 & 2 Perry, Ohio 44081 (P.O. Box 85)

III) Component Supplier Conax Buffalo Corporation 2300 Walden Avenue Buffalo, New York 14225 IV) Nature of Potential Defect The nature of the potential defect, as designated by Conax, is a loss of electrical continuity, resulting from a gradual reduction in the cross-sectional area of the conductors in the internal sealant area of the gland and eventually leading to total conductor separation in some cases. The phenomea appears to be related to time, temperature, and initial assenbly torquing and may be unique to Vermont Yankee's normal operating environment.

The result of phenomea could affect the electrical performance of safety related equipment into which these assemblies have been installed.

V) Date of Information This potential defect was brought to my attention in a meeting held on August 27, 1984 by S. M. Dale, Chief Engineer of our Industrial Products Division and W. C. Federick, Manager of our Nuclear Products Division.

VI) Number and Location of Components A. Forty-six (46) Power Lead Gland Assenblies, as follows, were supplied to Vermont Yankee Nuclear Plant in July,1984

• 26 pcs - 2 conductor /16 AWG (Conax P/N N-11150-01) 20 pcs - 8 conductor /14 AWG (Conax P/N N-lll51-01)

8. Eicfit hundred and twenty-one (821) Power Lead Gland Assemblies, as follows, were supplied to Perry Wclear Power Plant, thiits 1 and 2, in March thru June of 1984.

69 pcs - 2 conductor /14 AE (Conax P/N 752-11000-01) 128 pcs - 4 conductor /14 AWG (Conax P/N 7D92-11000-02) . i 57 pcs - 6 conductor /14 AWG (Conax P/N 7D92-11000-03)' l 9 pcs - 8 conductor /14 AWG (Conax P/N 7D92-11000-04) l 294 pcs - 2 conductor /16 AWG (Conax P/N 7092-11001-01) 55 pcs - 4 conductor /16 AWG (Conax P/N 7092-11001-02) 3 pcs - A conductor /16 AWG (Conax P/N 752-11001-03) l 9 pcs - 8 conductor /16 AWG (Conax P/N 7D92-11001-04) 197 pcs - A conductor /16 AWG (Conax P/N 7092-11001-05)

VII) Corrective Action Both Vermont Yankee Nuclear Plant and Perry Nuclear Power Plant, Units 1 and 2, were notified on August 27, 1984 concerning the potential defect and of our requirement to report to the NRC. At that point, Vermont Yankee had already removed all their Power Lead Gland Assemblies from service. Within the next 180 days, Conax will complete an evaluation of the parameters that may cause this potential defect and will advise the Perry Nuclear Power Plant of the results. ,

VIII) Recommendations and Advice Until the causes of the potential defect are determined, Conax is unable to fully evaluate the existance of a safety hazard for the Perry Nuclear Power Plant. Conax will provide information as it becomes available to the Perry Nuclear Power Plant for their assessment of the situation.

Conax recommends that the Power Lead Glands not be utilizeo in any safety related circuits until the evaluation is complete.

For further clarification of our position or any additional information, please contact me directly.

Very truly yours, CONAX BUFFALO CORPORATION b S. Rautio President WSR/ct

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.4 cc: Boyce H. Grier, Director, Region 1 Office of Inspection and Enforcement -

U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 Mr. Richard Pagodin Engineering Support Supervisor Vermont Yankee Nuclear Power Corporation P.O. Box 157 Vernon, VT 05354 Mr. George Hengerly Yankee Atomic Electric Company 1671 Worcester Road Framingham, MA 01701 MR. Paul Martin General Supervisory Engineer PAQS The Clevelano Electric Illuminating Company Perry Nuclear Power Plant, Units 1 ano 2 P. O. Box 85 Perry, Ohio 44081 Conax Buffalo Corporation: M. W. Connell J. E. Adams R. A. Fox

0. P. Jensen W. C. Federick R. L. Duroure R. E. Farchmin S. M. Dale l

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