ML20085K129

Ao:On 731127,cleanup Valve MO-3-1201-2 Failed to Isolate on Reactor Low Water Level Scram.Caused by Tarnished M Coil in Breaker Auxiliary Contacts.Contacts Cleaned

ML20085K129
Person / Time
Site:	Dresden
Issue date:	12/06/1973
From:	Worden W COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085K131	List: ML20085K129 ML20085K132 ML20085K134
References
891-73, NUDOCS 8310200132
Download: ML20085K129 (2)

Text

_

~

alth Edison Cam

/,ff%

,,-y one Fir:,. acnal Plata. Chicago, Ilhnois '

Address Reply to: Pcat Office Box 767

%W- % )J Chicago, Illinois 60690 ,

WFW Ltr.#891-73 Dresden Nuclear Power Station R. R. #1 ]d; Morris, Illinois 60450 M3 -

/ '.

December 6, 1973 N 1 /M! *Ii h bf ,-l, a 4 l l Jl~t. .

%c20197,,);;

D' 3 Mr. J. F. O' Leary, Director . hf

. $[D S Directorate of Licensing \o; t

'I h7f, [h' U. S. Atomic Energy Commission Washington, D. C. 20545 (%1D/4'W'

SUBJECT:

LTCENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT #3, PIPORT OF ABNORPAL OCCURRENCE PER SECTION 6.6.B.1 07 THE TEC'iNICAL SPECIFTCATIONS.

FAILURE OF REACTOR CLEAN UP SYSTEM VALVE MO-3-1201-2 TO OPERA %

References:

1) Notification of Region III of AEC Regulatory Operations Telephone: F. Maura, 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on November 28, 1973 Telegram: Keppler, 1620 hours0.0188 days <br />0.45 hours <br />0.00268 weeks <br />6.1641e-4 months <br /> on November 28, 1973

2) DWGS: P & ID M-361

Dear Mr. O' Leary:

This letter is to report a condition relating to the operation of the unit at about 2011 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.651855e-4 months <br /> on November 27. At this time MO-3-1201-2 failed to isolate on a reactor low water level scram. This malfunction is.

contrary to section 3.7.D.1 of the Technical Specifications which requires that the isolation valve be operable during reactor power operating conditions.

PROBLEM -

At 2011 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.651855e-4 months <br />, Unit 3 was operating at 2178 MWt and 729 MWe. The cleanup system was in service and operating. The reactor scrammed on low water level. As a result of the scram, the clean-up valve, MO-3-1201-2, failed to isolate. This valve is the second isolation valve in the system.

The first isolation valve, MO-3-1201-1, operated as designed.

INVESTICATION While investigating this incident, it was found that the breaker auxiliary contacts for the "H" coil were tarnished. This condition prevented the proper operation of the contacts which thus prevented the valve motor from operating.

b 8310200132 731206 PDR ADDCK 05000249 PDR

h d'

0 i o-(90 O

' S i d

\ 'W 'a

\ V d{

COPY SENT REGI

~

. Mr. J. F. O'L ,_.) Dec=bar 6,1973 CORRECTIVE ACTION l

The tarnished contacts were cleaned and the valve was tested. It operated satisfactorily.

in light of this incident, the station is initiating a program to inspect all breakers for DC motor operated isolation valves. These inspec-tions will include cleaning contacts and adjusting the contact pressure as necessary. Valve breakers will be inspected as the valves become available during outages.

EVALUATIONS This valve malfunction did not jeopardize the safety of the public or plant personnel because the redundant valve in this line functioned

, properly. Consequently, startup of the unit was considered safe. A similar problem has been experienecd recently on motor operated valve 2-220-2 on

Unit 2. However, these two

:alfunctions do not constitute an unsafe trend and the corrective actica being initiated will prevent such a trend from being established.

Sincerely, W. YOt. ~

W. P. Worden .

Superintendent Dresden Nuclear Power Station WFW:do i

l I

i t

4 f.

I d

,. . - _ . . . - , ,, , , .-.