United States Nuclear Regulatory Commission - Protecting People and the Environment

LICENSEE: ILLINOIS POWER CO.                 
SITE: CLINTON 1                             EN NUMBER:28841
DOCKET: 05000461                         EVENT DATE: 03-25-95
RX TYPE: BWR                             EVENT TIME: 00:00
VENDORS: GE-6                           NOTIFY DATE: 05-22-95
EMERGENCY CLASS: N/A  REGION: 3 STATE: IL      TIME: 16:51
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       Y    100   POWER OPERATION  100   POWER OPERATION

10 CFR PART 21 INTERIM REPORT NO. 21-95-010:  ELGAR INVERTER     
PULSE WIDTH MODULATOR (PWM) DRIVE LOGIC CARD (J4) FAILURE.       
                                                                 
ON MARCH 24, 1995, THE LICENSEE INSTALLED A NEW PWM DRIVE LOGIC  
CARD IN THE DIVISION 2 NUCLEAR SYSTEMS PROTECTION SYSTEM (NSPS)  
INVERTER, AND IT FAILED AFTER 4 TO 6 HOURS OF OPERATION DURING   
CALIBRATION OF THE INVERTER.  THE INVERTER WAS OUT OF SERVICE AT 
THE TIME OF THE FAILURE IN ORDER TO FACILITATE THE REPLACEMENT OF
THE LOGIC CARD WITH A REVISED CARD IN ACCORDANCE WITH A SCHEDULED
MAINTENANCE ACTIVITY.  THE LICENSEE DOES NOT KNOW THE CAUSE OF   
THE FAILURE, BUT HAS RETURNED THE LOGIC CARD TO THE SUPPLIER FOR 
FAILURE ANALYSIS.  THE LICENSEE DETERMINED THAT THE FAILURE WAS A
CONDITION POTENTIALLY REPORTABLE UNDER THE PROVISIONS OF 10 CFR  
PART 21 ON MARCH 25, 1995, AND EXPECTS TO COMPLETE THE EVALUATION
OF THIS ISSUE BY JUNE 30, 1995.                                  
                                                                 
THE BASIC COMPONENT INVOLVED WAS A PWM DRIVE LOGIC CARD (PART    
NUMBER NO. 642-108-40, REVISION F) WHICH WAS MANUFACTURED BY     
ELGAR CORPORATION AND SUPPLIED TO THE LICENSEE BY ELGAR          
CORPORATION/GENERAL ELECTRIC.  THIS LOGIC CARD WAS INSTALLED IN  
THE DIVISION 2 NSPS INVERTER WHICH PROVIDES 120-VOLT AC          
UNINTERRUPTIBLE POWER TO LOADS SUCH AS NSPS LOGIC POWER, NEUTRON 
MONITORING, PROCESS RADIATION MONITORING, PORTIONS OF THE LEAK   
DETECTION SYSTEM, NUCLEAR STEAM SUPPLY SHUTOFF SYSTEM VALVES, AND
LOSS OF COOLANT ACCIDENT BYPASS RELAYS DURING ALL MODES OF       
OPERATION, INCLUDING ABNORMAL AND ACCIDENT CONDITIONS.  THE LOGIC
CARD ALSO PROVIDES CONTROL SIGNALS TO THE SILICON CONTROLLED     
RECTIFIER DRIVES.  THE SAME LOGIC CARD CAN BE UTILIZED IN THE    
DIVISION 1, 2, 3, AND 4 NSPS INVERTERS, BUT THE REVISED CARD WAS 
NEVER INSTALLED IN THE DIVISION 3 OR 4 NSPS INVERTERS.  ANOTHER  
NO. 642-108-40, REVISION F, LOGIC CARD WAS IDENTIFIED AS         
DEFICIENT WHEN IT WAS INITIALLY INSTALLED IN THE DIVISION 1 NSPS 
INVERTER DURING A SIMILAR MAINTENANCE ACTIVITY.  THE SILICON     
CONTROLLED RECTIFIER DRIVE SECTION OPERATION WOULD NOT FUNCTION, 
AND THE DIVISION 1 NSPS INVERTER WOULD NOT OPERATE.  BOTH OF THE 
FAILED LOGIC CARDS WERE RETURNED TO ELGAR CORPORATION FOR FAILURE
ANALYSIS.                                                        
                                                                 
THE FAILURE OF THIS LOGIC CARD CAUSES THE INVERTER TO SHUT DOWN. 
WHEN THIS OCCURS, THE INVERTER LOADS ARE TRANSFERRED TO THE      
ALTERNATE AC SOURCE OF POWER.  IF THE LOGIC CARD HAD FAILED      
DURING A LOSS OF OFFSITE POWER CONDITION, THE NUCLEAR SYSTEMS    
PROTECTION SYSTEM LOADS WOULD BE TRANSFERRED TO AN ALTERNATE AC  
POWER SOURCE WHICH MAY NOT BE AVAILABLE DUE TO THE LOSS OF       
OFFSITE POWER CONDITION, AND THE NUCLEAR SYSTEMS PROTECTION      
SYSTEM COULD LOSE POWER.                                         
                                                                 
THE LICENSEE HAS NO INFORMATION ABOUT LOGIC CARDS THAT MAY HAVE  
BEEN SUPPLIED TO OTHER PURCHASERS.                               

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