ML20084V027

Ro:On 720303,while Surveillance Test Being Conducted on LPCI in Preparation for Maint Outage,Discovered That Torus Spray Isolation Valve 3-1501-19B Would Not Operate Remotely.Caused by Galling Between Worm & Worm Gear.Worm Gear Replaced

ML20084V027
Person / Time
Site:	Dresden
Issue date:	04/03/1972
From:	Worden W COMMONWEALTH EDISON CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084V010	List: ML20084V023 ML20084V027
References
NUDOCS 8306290722
Download: ML20084V027 (3)

Text

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O n go.a9 Commonwealth Edison Company ONE FIRST NATSONAL PLAZA

• C H I C A G O. ILLINOIS Address Eeoly to:

PO51 OFFICE tox 747

• C H I C A G o. I t t l N O IS 60690 Dresden Nuclear Power Station ,, ,

R. R. #1 Q ? "[ g' Q y Morris, Illinois 60450 .-/

April 3, 1972 </ 1 k ~'

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$ 34 9. ..Q,g;  ?

Dr. Peter A. Morris, Director s.N Division of Reactor Licensing U.S. Atomic Energy Commission r Tip/

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Washington, D.C. 20545 2)T}M

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SUBJECT:

LICENSE DPR-25, DRESD3N NUCLEAR POWER STATICN UNIT #3, SECTION 6.6.C.1 0F THE TECHNICAL SPECIFICATIONS.

Dear Dr. Morris:

This is to report a condition relating to the operation of the station when during surveillance testing of the Low Pressure Coolant ,

Injection System, Torus Spray Isolation Valve 3-1501-19B failed to open remotely.

PROBLEM AND INVESTIGATION At 0230, 3 March 1972, with the reactor at a power level of 473 MWe, surveillance tests were being conducted on the Low Pressure Coolant Injection System (LPCI) in preparation for a Unit 2/3 Diesel Generator Maintencnce outage. During these tests, it was discovered that the Torus Spray Isolation valve 3-1501-19B would not operate remotely. The valve was opened manually and left in the open position pending an investigation by maintenance personnel to determine the cause of failure. Investigation revealed that a worm gear in the limitorque operator had failed due to galling between the worm and worm gear. The worm is of steel construction and the worm gear is brass. It is believed that the galling is the result

/ of an inadequate polish on the worm, see attached drawing, f ..

The failure of this valve did not render the containment cooling p( subsystem of the LPCI system inoperative, as defined in section 3.5.A.6 of F

'p ,) the Unit #3 Technical Specifications, because the valve was operable manu-ally and all other components of the system were operable remotely.

l Qu'2'f>h [

! 8306290722 720526 '

PDR ADOCK 05000249 S PDR

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lI mpv c:DTP REGION ' {/

s .,

Dr. Peter A. Ho s ()

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April 3, 1972 CORRECTIVE AC' ION The defective worm and worm gear of the Torus Spray Isolation Valve 3-1501-19B notor operator were replaced, the torque setting was reduced from 2/5 to 1.0 and the operator was inspected and reassembled.

The manufacturer has been contacted for recommendations to alleviate the problem and prevent reoccurrence. The nanufacturer will supply the station with ten operators in exchange for ten typical operators of the type which have exhibited this problem and conduct tests at the factory to determine the cause of failure. A program will be initiated to inspect all valve operators of this type for defective drive gears.

Sincerely,

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fu ix 5 .f l,t e,m t .

yet W. P. Worden

< Superintendent WPW:do Enc l

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