ML20084N748

AO 50-249/75-39:on 750826,overload Relay Tripped Twice on Motor Operated Isolation Valve 3-220-1.Caused by Defective Overload Relay.Relay Replaced

ML20084N748
Person / Time
Site:	Dresden
Issue date:	09/03/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
577-75, NUDOCS 8306090058
Download: ML20084N748 (2)

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Commohlth Edison

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, Oni First 14ananal Plaza. ChicaQo filinois Address Reply to: Post Office Box 767

.Y Chicago, Illinois 60690 BBS Ltr. #577-75 Dresden Nuclear Power Station R. R. #1 Morris, Illinois 60450 Septesnber 3,1975 SECG.;7)0

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Mr. James G. Keppler, Regional Director s ',

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Directorate of Regulatory Operation-Region III U. S. Nuclear Reculatory Co::raission 799 Roosevelt Road D'

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Glen Ellyn, Illinois 60137

SUBJECT:

REPOPT OF ASNORMAL OCCURRE;CE PER SECTION 6.6.A 0F THE TECHNICAL SPECIFICATIONS MAIN STEi'4 LI:JE DRAIN VALVE MO 3-220-1 OVERIDAD RELAY PAILURE

References:

1) Regulatory Guide 1.16 Rev 1 Appendix A

2) Notification of Region III of U. C. Nuclear Regulatory Comission Telephone R. Knop,1710 houre on August 26, 1975 Telegram:

J. Keppler,1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br /> on August 27, 1975

3) Drawing Nu:nber M-345 and 12E-3505A Report Number: 50-249/75-39 Report Date: September 3, 1975 Occurrence Date: August 26, 1975 Facility: Dresden Nuclear Power Station, Morris, Illinois IDB7PIFICATICN OP OCCURRENCE The overload relay tr$pped twice on motor-operated inolation' valve 3-220-1, located inboard on the main steam drain line. This represents an abnomal occurrence because the malfunction of this valve could affect primary containment integrity.

CONDITIONS PRIOR TO OCCigBENCE Unit-3 was in the shutdown mode for a refbeling outage.

DESCRIPTION OP OCCURRHiCE At approxizr.ately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on August 14, 1975, valve 220-1 was being functionally tested to evaluate changes which had been made to the torque switch settings.

During the testing the valve tripped twice.

8306090058 75090 WPY SENT REGION _ / /b DR ADOCK 050002 9 g

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September 3, 1975 i

DESIGNA. ION OF APPARDIT CAUSE OF OCCURRENCE (Component Failure)

On August 26 an investigation revealed that the valve motor had tripped because of a defective overload relay. The relay appeared to be thernally damaged, but the cause of the damage is unknown. The motor current was measured and found to be within reasonable limits. The overload relay was apparently opening in response to norz.al current loads. The relay should not open unless the motor current becomes excessive.

ANALYSIS OF OCCURRH;CE The malfunction of valve 220-1 had little safety significance. Had the valve tripped during reactor operation, the leakage past the outboard valve 220-2 would have been well within Technical Specification limits even in the event of a loss-of-coolant, accident.

Plant personnel and the public were not endangered by thic occurrence.

CORRECTIVE ACTION The overload relay was replaced, and the valve was cycled eatisfactorily several times.

PAILURE DATA The overload relay is a Ganeral Electric model CR 124-K028. This is the first time an overload relay has failed on this valve.

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