United States Nuclear Regulatory Commission - Protecting People and the Environment


LICENSEE: MGP INSTRUMENTS, INC.              

SITE: MGP INSTRUMENTS, INC.                 EN NUMBER:32725

DOCKET:                                  EVENT DATE: 06-12-97

RX TYPE:                                 EVENT TIME: 00:00

VENDORS:                                NOTIFY DATE: 08-05-97

EMERGENCY CLASS: N/A  REGION: 2 STATE: GA      TIME: 14:57

OPS OFFICER: LEIGH TROCINE            

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



10 CFR PART 21 NOTIFICATION REGARDING THE DISCOVERY THAT A       

RADIATION MONITORING SYSTEM POWER SUPPLY CIRCUIT BOARD IS SUBJECT

TO PREMATURE ELECTRONIC COMPONENT FAILURE                        

                                                                 

MGP INSTRUMENTS, INC., LOCATED IN SMYRNA, GEORGIA, REPORTED A    

POTENTIAL SAFETY-RELATED DEFECT INVOLVING DIODES IN RADIATION    

DETECTION MEASUREMENT EQUIPMENT WHICH WAS SUPPLIED TO SOUTHERN   

CALIFORNIA EDISON FOR USE AT SAN ONOFRE.  DIODE VD9 (MODEL       

#1N4148) WAS INSTALLED ON PROPRIETARY POWER SUPPLY BOARDS, AND   

THIS DIODE IS SUSCEPTIBLE TO FAILURE DURING EQUIPMENT START-UP.  

THE FAILURE IS DUE TO THE INSUFFICIENT RATING OF THE DIODE UNDER 

TRANSIENT CONDITIONS (NON-REPETITIVE PEAK FORWARD CURRENT).      

FAILURE OF THIS DIODE COULD ULTIMATELY RESULT IN THE INABILITY OF

THE LOCAL PROCESSING UNIT TO RESTART WITH CORRECT OPERATING      

PARAMETERS.                                                      

                                                                 

THE SAFETY-RELATED APPLICATION OF THIS DEVICE IS LIMITED TO ITS  

INSTALLATION IN 28 LOCAL PROCESSING UNITS AT SAN ONOFRE.  MGP    

INSTRUMENTS, INC., STATED THAT A RECENT INQUIRY OF THE UTILITY   

INDICATED THAT THE AFFECTED EQUIPMENT HAD NOT BEEN COMMISSIONED  

AND IS NOT YET IN SERVICE. PLANS ARE BEING MADE TO REPLACE THE   

DIODES WITH APPROPRIATE COMPONENTS PRIOR TO THE COMMISSIONING OF 

THE EQUIPMENT.                                                   

                                                                 

(REFER TO THE HOO LOG FOR CONTACT NAMES AND TELEPHONE NUMBERS.)  



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