United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: COMMONWEALTH EDISON CO.            

SITE: BYRON 1 2                             EN NUMBER:31890

DOCKET: 05000454 05000455                EVENT DATE: 03-03-97

RX TYPE: PWR PWR                         EVENT TIME: 00:00

VENDORS: W-4-LP W-4-LP                  NOTIFY DATE: 03-04-97

EMERGENCY CLASS: N/A  REGION: 3 STATE: IL      TIME: 16:22

OPS OFFICER: HENRY BAILEY             

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   HOT SHUTDOWN       0   HOT SHUTDOWN   

 2    N       Y    100   POWER OPERATION  100   POWER OPERATION



10 CFR PART 21 NOTIFICATION - CRACKING OF VITEC TRANSFORMER CORES

                                                                 

THESE TRANSFORMERS ARE INSTALLED IN VARIOUS SAFETY-RELATED       

CIRCUITS BOARDS. TEMPERATURE CHANGES IN THESE CIRCUIT BOARDS     

COULD CAUSE ASSOCIATED INSTRUMENTATION TO DRIFT OUT OF RANGE.    

THE SAFETY-RELATED APPLICATIONS WHERE THIS TRANSFORMER HAS THE   

MOST POTENTIAL IMPACT ARE THE DELTA TEMPERATURE PROTECTION       

FUNCTIONS (NRA CARDS) IN THE REACTOR PROTECTION SYSTEM (RPS).    

THE DRIFT IN THE RPS COULD CAUSE A CHANNEL TO TRIP RESULTING IN A

LOSS OF REDUNDANCY IN THE DIVERSE TRIP FUNCTION.                 

                                                                 

NOTE:  THIS ISSUE ALSO APPLIES TO BRAIDWOOD UNITS 1 AND 2 AND TO 

ZION                                                             

       UNITS 1 AND 2.                                            



Page Last Reviewed/Updated Thursday, March 29, 2012