RE: Mag-thorium alloy

[montgomn@Medgate.mednet.af.mil]

     You wrote:
     
     >I have two magnesium-thorium castings that I want to dispose of. Each 
     >weighs about 25 pounds (11 kg). I am trying to estimate the amount of 
     >thorium in each. These were fabricated 30 - 40 years ago, and I have 
     >nothing to tell me the percentage of thorium in them.
     
     >Does anyone have information on mag-thor alloys, such as what an 
     >average thorium content might be?
     
     >Incidentally, I've measured about 2 mrad/hr (0.02 mGy/hr) 
     >window-open, and about 1 mrad/hr (0.01 mGy/hr) window-closed at the 
     >surface of these castings.
     
     A good guess is less than 4% thorium (the NRC limit for unimportant 
     quantities under 10 CFR 40.13).  I have seen alloys typically around 
     2.5%. 
     
     >Bruce Pickett
     >The Boeing Company, Seattle, WA
     >bruce.d.pickett@boeing.com
     
     
     Capt Noel Montgomery, CHP
     Kirtland AFB Radiation Safety Officer