United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: ILLINOIS POWER CO.                 

SITE: CLINTON 1                             EN NUMBER:34330

DOCKET: 05000461                         EVENT DATE: 03-14-98

RX TYPE: BWR                             EVENT TIME:   :  

VENDORS: GE-6                           NOTIFY DATE: 06-03-98

EMERGENCY CLASS: N/A  REGION: 3 STATE: IL      TIME: 10:25

OPS OFFICER: LEIGH TROCINE            

10 CFR SECTION: CCCC  21.21               UNSPECIFIED PARAGRAPH

UNIT  SCRAM   RX   INIT  INITIAL MODE     CURR   CURRENT MODE

      CODE   CRIT  PWR                    PWR

 1    N       N      0   COLD SHUTDOWN      0   COLD SHUTDOWN  



NOTIFICATION IN ACCORDANCE WITH 10 CFR PART 21 - RMX-TYPE KEPCO, 

INC., POWER SUPPLY FAILURES  (REFER TO EVENT #33710 FOR          

ADDITIONAL INFORMATION.)                                         

                                                                 

THE FOLLOWING TEXT IS A PORTION OF A FACSIMILE RECEIVED FROM THE 

LICENSEE:                                                        

                                                                 

"ON FEBRUARY 13, 1998, A NUCLEAR SYSTEMS [PROTECTION] SYSTEM     

[(NSPS)] 12-VOLT DIRECT CURRENT [(VDC)] POWER SUPPLY FAILED      

CAUSING THE DIVISION II NSPS INVERTER TO REVERSE TRANSFER TO THE 

BYPASS TRANSFORMER WHICH WAS OUT OF SERVICE FOR MAINTENANCE.     

THIS RESULTED IN A LOSS OF SHUTDOWN COOLING AS DESCRIBED IN NRC  

EVENT [NUMBER 33710 AND LICENSEE EVENT REPORT NUMBER 98-003-01]. 

THE CAUSE OF THE POWER SUPPLY FAILURE WAS AN INADEQUATELY        

DESIGNED OUTPUT TRANSISTOR PAIR COMBINED WITH DEGRADED           

CAPACITORS."                                                     

                                                                 

"THE COMPONENT INVOLVED IN THIS REPORT IS A 12-VDC POWER SUPPLY, 

MODEL NUMBER RMX12-D-20993, [WHICH WAS] SUPPLIED TO CLINTON POWER

STATION.  THIS CONDITION WAS ALSO IDENTIFIED TO EFFECT MODEL     

NUMBERS RMX24-D-20804 AND RMT001-AA-20995.  THE POWER SUPPLY WAS 

MANUFACTURED BY KEPCO, [INC.], AND [IT] WAS PURCHASED BY GENERAL 

ELECTRIC (GE) AS A NON-SAFETY-RELATED COMPONENT."                

                                                                 

"THE SUPPLIER PROVIDED MARGINALLY RATED OUTPUT TRANSISTORS IN THE

POWER SUPPLY.  THESE TRANSISTORS, AGGRAVATED BY DEGRADATION OF   

THEIR ELECTROLYTIC FILTER CAPACITORS, FAILED, PRODUCING A        

PHASE-TO-PHASE SHORT ON THE NSPS BUS.  THE LARGE CURRENT DRAW    

CAUSED THE INVERTER TO REVERSE TRANSFER AS DESIGNED TO CLEAR THIS

FAULT.  SINCE THE ALTERNATE SOURCE WAS UNAVAILABLE, THE CONDITION

RESULTED IN A LOSS OF POWER TO THE NSPS BUS LOADS WHICH INCLUDED 

THE PRIMARY VALVE FOR THE SHUTDOWN COOLING MODE AT THE TIME OF   

THE EVENT.  THE LOSS OF POWER TO THE VALVE CAUSED THE VALVE TO   

CLOSE AND SHUT OFF SHUTDOWN COOLING.  IN ADDITION, GE PARTS LIST 

DRAWING [NUMBER] 169C8805 IDENTIFIES THE POWER SUPPLY AS         

NON-SAFETY RELATED, AND [CLINTON] PURCHASED THE POWER SUPPLIES AS

NON-SAFETY-RELATED.  HOWEVER, BASED ON THE APPLICATION OF THE    

POWER SUPPLIES AND GE SPECIFICATION [NUMBER] 22A7822, REVISION 1,

THE POWER SUPPLIES SHOULD BE CLASSIFIED AS SAFETY RELATED.       

SUBSEQUENTLY, [CLINTON] HAS REVISED THE MASTER EQUIPMENT LIST TO 

CHANGE THE CLASSIFICATION OF THE POWER SUPPLIES."                

                                                                 

"[THE LICENSEE] IDENTIFIED ON MARCH 12, 1998, THAT THE POWER     

SUPPLY FAILURE DURING STARTUP OF THE DIVISION [II] NSPS BYPASS   

TRANSFORMER ON FEBRUARY 13, 1998, MAY HAVE CAUSED THE INVERTER TO

REVERSE TRANSFER.  SUBSEQUENTLY, ON MARCH 14, 1998, THE RESULTS  

OF THE FAILURE ANALYSIS PERFORMED BY INTEGRATED RESOURCES, INC., 

CONFIRMED THAT THE POWER SUPPLY FAILURE WAS THE CAUSE OF THE     

REVERSE TRANSFER.  THE OUTPUT TRANSISTORS WERE UNDERRATED AND    

ARE, THEREFORE, REPORTABLE UNDER 10 CFR [PART] 21."              

                                                                 

"RMX-TYPE KEPCO, INC., POWER SUPPLIES ARE IN USE AT [CLINTON] FOR

ALL [4] DIVISIONS OF NSPS (16 TOTAL), NEUTRON MONITORING SYSTEM  

(24 TOTAL), AND THE DISPLAY CONTROL SYSTEM (2 TOTAL).  CURRENTLY,

[CLINTON] IS EVALUATING THE IMPACT ON ALL KEPCO SUPPLIED RMX-TYPE

POWER SUPPLIES."                                                 

                                                                 

"[THE LICENSEE PLANS TO] REPLACE THE OUTPUT TRANSISTORS AND      

DEGRADED CAPACITORS, DUE TO PREMATURE AGING, IN KEPCO RMX-TYPE   

POWER SUPPLIES."                                                 

                                                                 

"[THE LICENSEE] RECOMMENDS EVALUATION OF RMX-TYPE POWER SUPPLIES 

MANUFACTURED BY KEPCO, INC., FOR CONDITIONS SIMILAR TO THOSE     

DESCRIBED IN THIS REPORT."                                       



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