Re: Radiation levels long ago

["Andrew Karam" <akaram@safety.rochester.edu>]

>Due to radioactive decay the natural radiation levels were larger long ago.
>Has anyone seen an article on natural radiation levels very long ago (some 
>millions of years)?
>LP
> 

Dear Dr. Persson:

I looked into this topic recently for my MS research.  Briefly, radiation
dose from geologic and internal beta and gamma emitters reached a
(calculated) maximum of about 7 mGy/yr about 4 billion years ago and have
decreased more or less monotonically since.  It is interesting to note,
however, that radiation dose from nearby supernovae would be expected to
reach levels of about 1 Gy every 2-5 million years.  I'll be looking into
this during my dissertation research.

If you would like more details, please feel free to contact me.

Andy

Andrew Karam, MS, CHP				
RSO, University of Rochester			  
(716) 275-3781 (voice)						
(716) 256-0365 (fax)
akaram@safety.rochester.edu

"The mind is not a vessel to be filled  but a fire to be lighted" 
 Plutarch