United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: DUQUESNE LIGHT CO.                 

SITE: BEAVER VALLEY 2                       EN NUMBER:32216

DOCKET:  05000412                        EVENT DATE: 04-24-97

RX TYPE:  PWR                            EVENT TIME: 00:00

VENDORS:  W-3-LP                        NOTIFY DATE: 04-24-97

EMERGENCY CLASS: N/A  REGION: 1 STATE: PA      TIME: 14:03

OPS OFFICER: BOB STRANSKY             

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

UNIT  SCRAM   RX   INIT  INITIAL MODE     CURR   CURRENT MODE

      CODE   CRIT  PWR                    PWR

 2    N       Y    100   POWER OPERATION  100   POWER OPERATION



10 CFR PART 21 REPORT REGARDING AUXILIARY FEEDWATER (AFW) CHECK  

VALVE FAILURE                                                    

                                                                 

THE LICENSEE HAS IDENTIFIED THAT NOZZLE CHECK VALVES MANUFACTURED

BY ENERTECH AND USED IN THE AFW SYSTEM MAY BE SUSCEPTIBLE TO A   

FAILURE IN WHICH THE SEATING RING CAN BECOME LOOSENED AND BE     

SWEPT INTO THE FLOW STREAM. THIS COULD CAUSE A PARTIAL BLOCKAGE  

AND POTENTIALLY PREVENT THE AFW SYSTEM FROM PERFORMING ITS       

INTENDED FUNCTION.                                               

                                                                 

THE PHENOMENON DESCRIBED IS ONE IN WHICH THE HOT VALVE BODY AND  

SEAT EXPERIENCE DIFFERENT RATES OF THERMAL CONTRACTION DUE TO THE

FLOW OF COOL AUXILIARY FEEDWATER CAUSING THE SEATING RING TO     

SHRINK TO THE POINT THAT THERE IS NO LONGER AN INTERFERENCE FIT  

BETWEEN THE RING AND THE VALVE BODY. THE RING COULD THEN BE SWEPT

INTO THE FLOW STREAM.                                            

                                                                 

THE LICENSEE REPORTED THAT ENERTECH HAS BEEN NOTIFIED OF THIS    

PHENOMENON AND HAS MODIFIED THE VALVES AT BEAVER VALLEY TO       

PREVENT THIS CONDITION IN THE FUTURE.                            



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