ML20100G357

Forwards Wyle Lab Rept, Test Program to Determine Effects of Continuous 120% Rated Current on Motor Control Ctr Contactors During Normal & Extreme Svc Conditions, Per GDC 17.Replacement Schedule for Coils Listed

ML20100G357
Person / Time
Site:	North Anna
Issue date:	03/29/1985
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Harold Denton, John Miller Office of Nuclear Reactor Regulation
Shared Package
ML20100G362	List: ML20100G357 ML20100G371
References
696C, NUDOCS 8504080224
Download: ML20100G357 (2)

Text

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I Nuckte qwrathns oneJaurusRhnvitwa 14&mant Veryn212326i March 29, 1985 VIRGINIA P09WR Mr. Harold R. Denton, Director Serial No. 696C Office of Nuclear Reactor Regulation EC/JHG:mjp Attn:. Mr. James R. Miller, Chief Docket Nos. 50-338 Operating Reactors Branch No. 3 50-339 Division of Licensing License Nos. 'NPF-4 U. S. Nuclear Regulatory Commission NPF-7 Washington, D. C. 20555 Gentlemen:

VIRGINIA POWER NORTH ANNA UNIT N05. 1 AND 2 GEN 6 SIS Your letter of November 13, 1984, provided a revised and updated Safety Evaluation for North Anna Units 1 and 2 with relation to GDC-17. In that letter, it was requested that the NRC be kept apprised of the status of the motor control center contactor coils until the final report regarding this matter is submitted for NRC review.

In our letter of July 7,1983 (Serial No. 326), Virginia Power stated that tests would be performed on IE motor control center contactor coils to determine the effects of overvoltage. Enclosed is a copy of the report for your review.

The overvoltage tests and preparation of the test report were performed by Wyle Laboratories. Actual aging and overvoltage testing was conducted on size one and size four contactor coils. The size one coils were used as typical test specimens for size two and smaller coils due to similar design and construction. The. size four coils were used as typical test specimens for size three and larger coils for the same reason. As a result of preliminary information received during coil testing, Virginia Power reviewed the operating duty cycles for all size two and smaller coils in anticipation of the need for a coil replacement schedule. A review of operating duty cycles for all size three and larger coils was not conducted since preliminary information received during coil testing indicated that forty year life was obtainable. However, an aged forty year life,100% duty cycle, size four specimen failed during operation at its equivalent life of 40.03 years, which removed forty years as an acceptable qualified life.

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WRGINIA POWER Mr. Harold R. Den h n, Director ,

.Page 2 Virginia Power has reviewed the test report and, based on known operating duty cycles, recommends the following replacement schedule for size two and smaller coils. All existing and future size two and smaller contactor coils that operate'between 51-100% duty will be replaced approximately every ten to twelve years (based on a qualified life of 13.15 years). Approximately eighteen contactor coils-in Units 1 and 2 fall into this category. All existing and future size two and smaller contactor coils that operate' between 21-50% duty will be replaced approximately every twenty to twenty-two years.(based on a qualified life of 23.71' years). - Approximately fifty-nine contactor coils in Units 1 and 2 fall into this category. Existing and future size two and smaller contactor coils that operate less than 20% duty were tested positively to an equivalent forty year life at 100% duty cycle. Size three and larger

. contactor coils were tested and evaluated to have a 35.08 year life at 100%

duty cycle. Virginia Power will by June 30, 1985 review and evaluate the operating duty cycles on these larger coils and recomend any required replacement schedule at that time. We will inform you of our resolution of this matter at that time.

Please contact this. office if you require additional information, fr tylyyaurs, k,' Stewart 1%,

W. L.

WTM:mjp:2005N cc: Dr. J. Nelson Grace Regional Administrator i Region II '

l Mr. M. W. Branch i

'NRC Resident' Inspector i North Anna Power Station i I

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