United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: ILLINOIS POWER CO.                 

SITE: CLINTON 1                             EN NUMBER:33800

DOCKET: 05000461                         EVENT DATE: 02-26-98

RX TYPE: BWR                             EVENT TIME: 16:18

VENDORS: GE-6                           NOTIFY DATE: 02-26-98

EMERGENCY CLASS: N/A  REGION: 3 STATE: IL      TIME: 16:18

OPS OFFICER: JOHN MacKINNON           

10 CFR SECTION: CDEG  21.21(c)(3)(i)      DEFECTS/NONCOMPLIANCE

UNIT  SCRAM   RX   INIT  INITIAL MODE     CURR   CURRENT MODE

      CODE   CRIT  PWR                    PWR

 1    N       N      0   COLD SHUTDOWN      0   COLD SHUTDOWN  



10CFR PART 21 REPORT - DIVISION 2 NUCLEAR SYSTEMS PROTECTION     

SYSTEM INVERTER NOT IN ACCORDANCE WITH THE PLANT'S DESIGN BASIS  

DUE TO VARIOUS DEFICIENCIES.                                     

                                                                 

WITH THE PLANT IN COLD SHUTDOWN, PLANT TECHNICIANS IDENTIFIED    

VARIOUS DEFICIENCIES IN THE INSTALLED SILICON CONTROLLED         

RECTIFIERS (SCR) AND POWER DIODES OF THE DIVISION 2 NUCLEAR      

SYSTEMS PROTECTION SYSTEM (NSPS) INVERTER. THE COMPRESSIVE FORCE 

APPLIED TO THE HEAT SINK CLAMP HARDWARE FOR SCRs AND POWER DIODES

HAD BEEN APPLIED AND VERIFIED INCORRECTLY, CAUSING LOOSE         

CONNECTIONS.  THEREFORE, THE INVERTER LIKELY WOULD NOT HAVE BEEN 

CAPABLE OF PERFORMING ITS SAFETY FUNCTION DURING A SEISMIC EVENT.

 MISCALIBRATION OF THE INVERTER LOCK-UP DETECTOR ASSEMBLY        

RESULTED IN A LOSS OF THE SIMULATED INVERTER LOADS DURING TESTING

UNDER INVERTER FULL LOAD CONDITIONS, WHEREBY LOSS OF THE         

SIMULATED BYPASS POWER TEST SOURCE RESULTED IN A REVERSE TRANSFER

OF THE INVERTER TO THE MISSING BYPASS POWER TEST SOURCE, AND A   

LOSS OF POWER TO THE SIMULATED INVERTER LOAD BANK.  THESE        

CONDITIONS ARE NOT IN ACCORDANCE WITH THE PLANT'S DESIGN BASIS.  

A CAUSE EVALUATION FOR THIS EVENT HAS NOT BEEN COMPLETED AND     

CORRECTIVE ACTIONS HAVE NOT BEEN IDENTIFIED.  HOWEVER, THE       

DIVISION 2 NSPS INVERTER SCR AND POWER DIODE INSTALLATION HAVE   

BEEN CORRECTED AND OTHER INVERTERS WILL BE INSPECTED FOR SIMILAR 

DEFICIENCIES AND CORRECTED.                                      





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