ML17238A740
| ML17238A740 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/03/1972 |
| From: | Worden W Commonwealth Edison Co |
| To: | Morris P US Atomic Energy Commission (AEC) |
| References | |
| Download: ML17238A740 (4) | |
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SO *a. '1-9 Commonwealth Edison Comp~ny ONE FIRST NATIONAL PLAZA*
CHICAGO.
ILLINOIS Address Reply to, POST OFFICE BOX 767 *CHICAGO, ILLINOIS 60690 DOCKITED USAEC Dr. Peter A. Morris, Director Division of Reactor Licensing U.S. Atomic Energy Commission Washington, D.C.
20545 Dresden Nuclear Power Station R. R. iFl Morris, Illinois April 3, 1972 60450
SUBJECT:
LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION UNIT #3, SECTION 6.6.C.l OF 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 Valv~ 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 Maintenance outage.
During these tests, it was discovered that the Torus Spray Is.olation Valve 3-1501-19~ would' not operate remotely.
'fhe 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.
The failure of this valve did not render the containment cooling s~bsystem of the LPCI system inoperative, as defined in section 3.5.A.6 of the Unit #3 Technical Specifications, because the valve was operable manu-ally and all other components of the system were operable remotely.
~Dr. Peter A. ~is
- April 3, 1972 CORRECTIVE ACTION The defective worm and worm gear of the Torus Spray Isolation Valve 3-1501-19B motor 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 manufacturer 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 initi,i!ated to inspect all valve~::1 operators of this type for defective drive gears.
WPW:do Enc.
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Sincerely,
~JV-~ -.J. YW~
0..,. W. P. Worden r-superintendent
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