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Re: Thoriated Tungsten



>>From ed-at-alumni.caltech.eduSat Sep 28 21:36:18 1996
>Date: Sat, 28 Sep 1996 15:21:59 -0700 (PDT)
>From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
>To: Tesla-list-subscribers-at-poodle.pupman-dot-com, tesla-at-pupman-dot-com
>Subject: Re: Thoriated Tungsten vs Pure

>Thoriated tungsten is used for tube filaments because it hnas
>has much higher emission at lower temperatures than pure tungsten,
>hence lasts much longer.  Effect was discovered accidently in the
>early 1920's.  Thorium was originally added to light bulb filaments
>"to make them easier to draw through the wire dies" (per RCA
>Vaccum Tube Design Manual, circa 1940).
>Can't prove it, but suspect the radioactivity is barely detectable,
>and certainly not a health hazard.
>Ed Phillips
<snip>

Ed, All,

You are quite correct.  The ionizing radiation level at the surface 
of these thoriated tungsten TIG rods is barely above background. 

I have a geiger mueller civil defence type counter , Anton 
Electronics, CD V-700 Model No.5.  It measures MR/HR in three ranges.
The lowest (X1) range is 0 to 0.5 MR/HR.  The pickup tube is in a metal 
cylinder like a microphone.  There is a Gamma filter shield which you can rotate 
open to detect lower power Beta particles.  With this shield open, background
barely lifts the needle from the bottom stop at ~ 0.03 MR/HR.  When I 
place 10 of those thoriated tungsten rods in a bundle right against 
the detector I get a reading of 0.25 MR/HR.  When I hold the detector 
to the plastic face of a WWII vintage radium painted Solar watch I 
have it goes crazy reading 17 MR/HR (1/3rd up the X100 range).

I don't think you'd develop radiation ralated problems if you sprinkled the
dust from grinding these on your food every day for 30 years.  I 
suspect you'd probably suffer intestinal distention from heavy metal 
accumulation.  But you'd be a quicker quencher, and you wouldn't 
overheat. :-) 

By the way, these civil defence geiger counters are just the thing 
next to an alarm clock for your bedside table.  Seriously!  After the 
alarm awakens you, just check the GM machine.  If its emitting a 
cacophony and pegging the scale, just hit the ol' super snooze alarm. 
On this day you might as well sleep in! 

Regards,

rwstephens