ML20084K245

AO 50-254/74-22:on 740720,motor Speed Changer of HPCI Failed.Caused by Pulling Fuses 2330-700 & 2330-701.Speed Changer Motor Replaced,Administrative Controls Initiated & Wiring for Control Power Circuit Revised

ML20084K245
Person / Time
Site:	Quad Cities
Issue date:	07/26/1974
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084K248	List: ML20084K245 ML20084K253
References
AO-50-254-74-22, NJK-74-181, NUDOCS 8305190235
Download: ML20084K245 (3)

Text

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y y,' /,tyt;}&-c.t Mr. John F . O ' Leary, Di rector Directorate of Licensing Regulation U . S . A tomi c Energy Cornmi ss i on Wash i ngtori, D.C. 20545

Reference:

Quad-C i tics flucicar Power Station, Uni t I Docket flo. 50-254, DPR-29, Appendix A Sect ions 1.0.A.4, 3.5 C . i , 3.5.C.3, and 6.6.B . l .a

Dear Mr. O ' Leary:

Enclosed please find Abnormcl Occurrence Report tio. A0-50-254/74-22 for Quad-C i t ies :1uclear Power S tation. This was previously reported to Region ill, Directorate of Psegulatory Operations by telephone on July 20. 1974, and to you and Region t il , Directorate of Regulatory Operations by telecopy on July 20, 1974.

T!- i r: pert i: :ub--i t ted : ; u in :::crd:nt: "ith the requi rement: Of Technical S pecification 6.6.B.1.0.

. cry truly yours, 00!MOINEALTH EDI 50!! C0f tFAtiY ,

0UAD-CITIES INCLEAR POWER STAT 10:1

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o fl. J. Kalivianakis Station Superintendant t1JX/J LS /j eh cc: Region 111, Directorate of Regulatory Operations J. S. Abel I

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I R.C P03J. NUMBER : A0 254/74-22 i

REPORT DATE: July 30, 1974 OCCURRENCE DATE: July 20, 1974 FACILITY: Quad-Cities Nuclear Power Station Cordova, Illinois 61242 IDENTIFICATION OF OCCURRENCE:

ilPCI System inoperable due to motor speed changer failure.

CONDITIONS PRIOR TO OCCURRENCE _:

1. U-l reactor critical and in the startup mode.

2. U-l reactor paver 120 MWt and 0 MWe.

3 U-l reactor pressure 250 psig.

DESCRIFrl0N OF OCCUP.RENCE:

While conducting the startup tests required af ter the Unit i refueling outage, an attcmpt was made to start the High Pressure Coolant injection (!!PCI) System. The motor speed changer would not move and the control peacr fuses were blown. The

=e ra-fir:t Octic.7 tcher. .::: tc b gin to reduce rc::ter prc::ure te be'au 90 pe*g quired by Technical Speci fication 3.5.C . I . The speed changer motor was removed and it was detcrained that the motor windings were shorted togethe'r.

The motor was burned up because the system was improperly taken out of service earlier in the refueling outage. When the M0 2301-4 valve was taken out of ser-vice on May 2, 1974, not all of the necessary fuses were pulled. Fuses 2330-700 and 2330-701 were pulled which dropped out relay 2330-123 "B" contacts 7 & 3 then closed because the relay was dropped out. This action completed a circuit in the motor speed changer causing the speed changer motor to run. When the motor speed changer reached the low speed setting it closed the low speed limit switch. This should have caused the 2330-123 relay to energize and open "B" contacts 7 & 3 to stop the motor speed changer. Since fuses 2330-700 and 2330-701 were pulled the circuit to pick up relay 2330-123 was not complete. The motor continued to run causing a mechanical clutch to continually slip. Eventually the clutch wore down and froze causing the motor to draw high current. The accompanying heat dissipation eventually broke down the insulation and shorted the motor windings.

DESIGNATION OF APPARFNT CAUSE OF OCCURRENCE:

The cause of the failure is the pullino of fuses 2330-700 and 2330-701 causing the motor speed changer to run without pulling fuses at terminals CCF3-1 to CCF3-2 and CCF4-1 to CCF4-2. Pulling these two additional fuses would have interrupted con-trol power to the soced changer motor and thus prevented the motor from running.

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' A0-50-254/74-22 s,/ () July 30, '1974

' ANALYSIS OF OCCURRENCE: .i

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The consequence of this event is that the HPCI System was inoperable f rom the time the motor failed. The consequences of this are minimized because the HPCI System is not able to operate while the reactor is shutdown. With the reactor pressure at 250 psig the.HPCI System was tested to prove its operability. The reactor pressure was reduced below 90 psig when the system was_found to be inoperabic.

During the four hours'the reactor-pressure was' greater.than 90 psig but less than 250 psig and HPCI was inoperable the Core Spray System, the Low Pressure Coolant

' Injection (LPCI) mode of the Residual Heat Removal (RHR) System, the Reactor Coolant injection System (RCIC) and the Automatic Blowdown System were operable. Since the HPCI System is designed for all break sizes less than those for which'the LPCI and Core Spray System are-designed, the safety of the reactor was not jeopardized. Be-c'ause of this, the consequences on the health and safety of the public were negligibic.

CORRECTIVE ACTION:

The first corrective action was to replace the speed' changer motor with another. unit.

The second corrective action is to initiate administrative controls to ensure that this situation does not occur again. Ccution cards have been tied to each fuse warning anyone of the potential probicm.

As a final solution to this problem, a circuit modification has been initiated to revisc-the wiring for the control power circuit to prevent future occurrences of this failure.

-At about 7:20 p.m. July 20, 1974, the HPCI System was returned to service and a functional test was performed.

FAILURE DATA:

This is the first time a HPCI speed changer motor has been damaged due to such'an event.

The name plate data for the motor is:

General Electric

' MANUFACTURER:

MODEL NUMBER: 5BC26AC389 Totally Enclosed 0.10 HP @ 5160 RPM VOLT: 125 V DC 0.91 AMP FULL LOAD 18.9 AMP LOCKED ROTOR SHUNT WOUND

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