ML20084D645
| ML20084D645 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/12/1973 |
| From: | Worden W COMMONWEALTH EDISON CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084D648 | List: |
| References | |
| 2532, 289-73, NUDOCS 8304120152 | |
| Download: ML20084D645 (2) | |
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Commonwealth Edison Company ONE FIRST NATIONAL PLAZA
- C H I C A G O.
ILLINOIS Aeldreen 0 0 9 o:
1 C Polf O F FICE Sox 767
- C M IC A O o, i t L I N o l 540690 WPW Ltr.0289-73 Dresden Nuclear Power Station K. R. #1 Morris, Illinois 60450 April 12, 1973 ki l
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Mr. A. Giambusso 50-237 g
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,C Deputy Director for Reamr Projects
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Directorate of Licensit.;
U. S. Atomic Energy Commission
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Washington, D. C.
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SUBJECT:
LICENSE DPR-19, DRESDEN NUCLEAR PO'4ER STATION, UNIT #2, SECTION 6.6.C.1 0F THE TECHNICAL SPECIFICATIONS.
Dear Mr. Giambusso:
This is to report a condition relating to the operation of the unit in which, on March 15, 1973, a t 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, while performing quarterly timing checks on primary isolation valves, motor operated valve 2-2301-5 failed to open after being cycled closed. Motor operated valve 2-2301-5 is the steam line outboard isolation valve for the High Pressure Coolant Injection system (HPCI), and is normally open.
PROBLEM AND INVESTICATION While performing quarterly timing checks on the primary isolation valves, motor operated valve 2-2301-5 was cycled closed as part of the test.
When attempting to open the valve the breaker tripped, thus preventing the
, remote mode of valve operation.
The breaker was promptly reset and the valve opened, after which the valve was cycled closed and open several times satisfactorily.
Upon investigation it was found that the torque setting for valve
! seating was set at 2.5 which is higher than the setpoint recommended by the motor operator vendor. No other mechanical or electrical problems were identified during the inspection.
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- Mr. A. Giambusso April 12, 1973 A review of the trip setting for the circuit breaker, which is a Westinghouse two-pole type used in direct current circuits, and the thermal overload rating revealed that the circuit breaker trips af ter approximately 8 seconds with locked rotor current and the thermal overload trips af ter 10 seconds.
It is believed that the high setpoint on torque seating caused the valve to jam in its seat resulting in a locked rotor current condition during opening and subsequent breaker trip.
This is the first time a Westinghouse type breaker trip has been experienced at the station.
With valve M.O.2-2301-5 in the closed position, it momentarily placed the High Pressure Coolant Injection system out of service until D
the breaker could be reset. Although M.O.2-2301-5 was momentarily inoper-j able, other emergency core cooling systems were available.
CORRECTIVE ACTION The torque setting for valve seating was adjusted from 2.5 to 1.
In light of recent problems with motor operated valve breakers, torque switch settings, and thermal overloads, discussions with representatives from our Electrical Engineering Department and the Station are in progress.
A program for remedying the breaker, overload, and torque switch setting problems, which have been experienced, will be formulated by June 1,1973.
Sincerely, 2n b l. % a W. P. Worden
' Superintendent WPW:do ec: WPW Ltr. File i
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