ML20085K124
| ML20085K124 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/09/1974 |
| From: | Worden W COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 21-74, NUDOCS 8310200087 | |
| Download: ML20085K124 (2) | |
Text
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CammnCalth Edissn
((--[ef'f-One FirstK,nal Plaza. Chicago. Ilhno s Address Rep y to. Post Office Box 767 Chicago, Illinois 60690 WFW Ltr.921-74 Dresden Nuclear Power Station R. R. 41 Morris, Illinois 60450 CD January 9, 1974 s
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Mr. J. F. O' Leary, Director 17' O. e m ;; a y Directorate of Licensing Nalli$f,[.
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20545
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LICENSE DPR-25. DRESDEN NUCLEAR POWER STATION, UNIT #3 REPORT OF AN UNUSUAL EVENT PER SECTION 6.6.B.2 OF '1HE TECHNICAL SPECIPICATIONS.
FAILURE OF LOW PRESSURE COOLANT INJECTION VALVE M03-1501-118.
References:
- 1) Notification of Region III of AEC Regulatory Operations Telephone: Mr. F. Maura,1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on December 17, 1973
- 2) Dwas: P & ID M-360
Dear Mr. O' Leary:
This letter is to report a condition relating to the operation of Unit 3 at about 2345 hours0.0271 days <br />0.651 hours <br />0.00388 weeks <br />8.922725e-4 months <br /> on December 15,~ 1973. At this time Low Pressure Coolant Injection (LPCI) valve operability checks were in progress.
During these checks, LPCI valve H03-1501-11B failed to close when given a close signal from the control room. This malfunction is contrary to section 3.5.B.1 of the Technical Specifications which requires that the containment cooling systems be operable whenever irradiated fuel is in the reactor vessel and reactor coolant temperature is greater than 2120F.
f PROBLEM a
At the time of the occurrence, the unit was at 2232 MWt and 690 MWe. LPCI valve operability checks were being conducted on Unit 3 as required by the Technical Specifications Section 3.5.F.1.when the Unit #3-diesel generator is out of service.
i During these checks, it was discovered that containment cooling heat exchanger bypass valve M.0. 3-1501-11B would not close.
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o Mr. J. F. O'Le:ry J:auary 9, 1974 INVESTICATION An operator was sent to inspect the valve breaker.
The breaker was found in the tripped position and was reset. Following reset of the breaker, the valve was successfully cycled three times from the control room. The inspection revealed nothing which could have caused the breaker to trip.
CORRECTIVE ACTION The breaker was reset and the valve was successfully cycled three times frem the control room. The breaker for valve M03-1501-113 will be replaced with an identical model and the replaced breaker will be sent to Commonwealth Edison's Station Electrical Engineering Department for evaluacion. Further corrective action will depend upon the evaluation of the breaker by Station Electrical Engineering and their recommendations.
SAFETY EVALUATION This event did not jeopardire the safety of the plant or the public in any way. The valve operated properly after the breaker was reset and the valve was manually operable at all times.
In the case of a LOCA, there would have been adequate time to operate this valve manually.
The failure of this valve would cause a partial loss of cooling of the torus water by one of the two redundant containment cooling service water system loops, but would not have affected the ability of LPCI to deliver water to the reactor in the event of a LOCA.
The redundant system l
is capable of satisfying all containment cooling requirements.
The corrective action taken will be part of a continuing program to resolve the current motor-operated valve problem.
If evaluation of the breaker dictates further corrective action, such corrective action will be evaluated for applicability to sim,ilar breakers.
This event presented no ' reason for limiting continued operation of the unit.
Sincerely, U
s W. P. Worden Superintendent WPW:do
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P1S t:R JAffES 0 YsEPPLER 34
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RE010NAL DIRECTOR DIRECT 0!!IATE-0F GEGULATORY OPERATIO:iS REGION 3 VUX U S ATOMIC ENERGY COMMISSION 799 ROOSEVELT ROAD
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GLEN ELLYN ILL 60137 SUBJECT DPR-25 DRESDEN NUCLEAR POVER STATION UNIT 3.
THIS WILL CONFIRM A CONVERSATION WITH MR MAURA 0F YOUR OFFICE AT 1030 HOURS THIS DATE CONCERNIN3 A FAILUEE OF THE UNIT 3 DIEEEL CENERATOR COOLIN3 VATER FUNP.
Oli DECE!!aER 14, 1973 AT 0005 HOU!iS VHILE CONDUCTIN3 ROUTIf E POCT-NAINTENANCE SLGVEILLAliOE OF THE U!iIT 3 DIESEL GENERATOR THE 460 VOLT BREAKER FEEDI!?3 THE COOLING WATER PU.1P TRIPPED CAUSIN3 TifE DIESEL GENERATOR TO TRIP ON HIGH wwcnTEhrERATURE.
AL SYSTEMS REQUIRED TO DE OPERI. ELE VHEN T!2 UNIT 3
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DIESEL IS OUT OF SET:" ICE CEE IN1EDIATELY TESIED ;J:2 VEnIrIra 70 tz 05FMLE.
AN It.TESTICATION INTO THE CAUSE OF TEZ C00 LINT WIER FUNP FEE D EREMSP TF.lE IC UMEEi"'AY AT THIS TIF.E.
V P VORDEN, SUPERINTENDENT DRESDEN NUCLEAR POVER STATION Conn 0!NEALTH EDISON ConPANY ROUTE 1 MORRIS ILLIN0IS y
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RO Inspection Report No.
Transmittal Date Distribution:
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Address ply to: Post Othee Box 767 CNcago. Illinois 60690 WPW Ltr.f934-73 Dresden Nuclear Power Station i
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[N O'N Morris, Illinois 60450 December 27, 1973
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Mr. J. F. O' Leary, Director g
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SUBJECT:
LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT #3, REPORT OF UNUSUAL EVENT PER SECTICN 6.6.B.2 OF THE TECHNICAL SPECIFICATIONS.
MALFUNCTION OF HIGH PRESSURE COOIANT INJECTION HIGH FLOW SWITCH.
References:
- 1) Dwgs: P & ID M-51
Dear Mr. O' Leary:
This letter is to report a condition relating to the operation of the unit at about 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> on December 8,1973. At this time the high pressure coolant injection high flow switch DPIS 3-2353 was found to operate at 175 inches of water which is greater than the Technical Specification limit of 150 inches of water.
PROBLEM At the time of the occurrence, Unit 3 was operating at a steady j
load of 680 ifJe. During a routine surveillance it was found that HPCI high I
flow switch DPIS 3-2353 operated at a point 25 inches of water above the 150 inches of water limit. The switch was inspected and it was observed that the electrical wires inside the switch caused the high operating point.
IlWESTICATION The switch cover was removed and the setpoint was rechecked and found to be 145 inches of water which was within limits. The cause was determined to be friction on the dial indicator caused by the dial rubbing on the scale plate. This friction was caused by an excess length of wire pushing on the scale plate.
Six #10 AWG wires are terminated inside the switch with the excess pushed up into the switch housing. The wires apparently worked free to a position in which they pushed en the scale plate.
This caused the dial to rub on the scale plate and thus require more differential pressure than normal to trip the switch. When the wires were pushed back into the housing, the scale plate pressure was removed, and the switch operated at the required Technical Specification level.
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y. December 27, 1973 CORRECTIVE ACTION The immediate corrective action was to pull the excess slack out of the wires that terminate inside the switch. Additional action will be to notify Station Electrical Engineering of the problem and request a change in construction specifications to allow the use of smaller wire inside instruments.
In addition, a modification will be requested to remove the unused wires in all HPCI flow switches. This will reduce the number of wires that must be terminated in the switch housing.
EVALUATIONS The failed switch was one of two switches that would isolate the HPCI steam line in the event of a high flow condition.
The other switch DPIS 2352 was set at 144 inches of water and operated properly at that peint. Therefore, it is concluded that the safety of the plant personnel and of the general public was in no way compromised as a result of this switch failure.
This is the first malfunction of this type. This malfunction by itself does not reduce the safety of the unit's operation.
Sincerely,
.AL kG%E W. P. Worden Superintendent WFW:do 9
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