United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: VALCOR ENGINEERING CORPORATION     

SITE: VALCOR ENGINEERING CORPORATION        EN NUMBER:34262

DOCKET:                                  EVENT DATE: 05-19-98

RX TYPE:                                 EVENT TIME: 00:00

VENDORS:                                NOTIFY DATE: 05-19-98

EMERGENCY CLASS: N/A  REGION: 1 STATE: NJ      TIME: 15:59

OPS OFFICER: BOB STRANSKY             

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



10 CFR PART 21 REPORT                                            

                                                                 

FOLLOWING 6 TO 18 MONTHS OF CONTINUOUS ENERGIZED SERVICE, THREE  

VALCOR MODEL V70900-65-11 AIR PILOT VALVES FAILED TO STROKE      

CLOSED IMMEDIATELY UPON DEENERGIZATION WHEN INSTALLED IN THEIR   

RESPECTIVE SYSTEMS. DELAYS IN CLOSING HAVE RANGED FROM ONE TO    

FIVE MINUTES. DESPITE BEST EFFORTS, THE VENDOR REPORTED THAT     

CLOSING DELAYS HAVE NOT BEEN REPLICATED OUTSIDE OF THE PLANT     

SYSTEMS.                                                         

                                                                 

THE VENDOR REPORTED THAT A POTENTIAL CAUSE OF THE DELAYED CLOSING

IS THE POSSIBLE SUSCEPTIBILITY OF THIS PARTICULAR MODEL TO THE   

EFFECTS OF RESIDUAL MAGNETISM. DELAYED CLOSING MAY OCCUR WHEN THE

AIR GAP BETWEEN THE PLUNGER AND THE STOP BECOMES TOO SMALL OR IF 

THE PLUNGER MAKES CONTACT WITH THE STOP. EXTENDED PERIODS OF     

CONTINUOUSLY ENERGIZED SERVICE AND SUBSEQUENT COMPRESSION SETTING

OF THE O-RING SEAT MAY INDUCE THE SMALL AIR GAP CONDITION. AS A  

RESULT OF THE SMALL AIR GAP, THE VALVE MAY THEN BE SUBJECT TO    

RESIDUAL MAGNETISM FORCES, WHICH TEND TO PREVENT CLOSURE OF THE  

VALVE UPON DEENERGIZATION. OPENING OPERATION OF THE VALVE IS NOT 

AFFECTED.                                                        

                                                                 

THE V70900-65-11 IS AN AC POWERED VERSION AND IS THE ONLY VERSION

OF THE V70900-65 AIR PILOT SERIES SUBJECT TO THIS EFFECT. ONLY 46

UNITS OF THIS PARTICULAR MODEL HAVE BEEN DELIVERED, ALL TO THE   

SUSQUEHANNA STEAM ELECTRIC STATION. ALL OF THE UNITS HAVE BEEN,  

OR ARE SCHEDULED TO BE, MODIFIED BY VALCOR TO ELIMINATE THE      

POTENTIAL FOR RESIDUAL MAGNETISM EFFECTS.                        



Page Last Reviewed/Updated Thursday, March 29, 2012