Re: thoriated tungsten welding electrodes

[tdc@ehssun.lbl.gov (Ted M. de Castro)]

MOST if not ALL manual arc welding rods are Thoriated! - I am told it 
stabilizes the arc.

The only problem we have had with these is when they were used to weld some 
pre-WWII steel plates for a low background counting chamber - we had to 
decon the chamber before using it for counting.

To my knowledge we haven't done any direct analysis of our welders for this 
BUT I KNOW some of our welders have been on bio-assy from time to time for 
other reasons and I can't recall hearing about any readings of this sort.

Considering the pervasiveness of Thorium in manual arc rods and the number 
of welders who HAVE been monitored in shipyards and reactor facilities - I 
would expect the problem to have surfaced if there was a problem.

Ted de Castro

LBL