Re[2]: RADSAFE digest 760

["William Kolb" <William_Kolb_at_SETA@mail.hq.faa.gov>]

D.KING wrote:

>It could only have happened a billion or so years ago because natural uranium
>ain't what it used to be.  The substance we used to call "natural uranium"
>would now be called "enriched uranium".

>The point of noting the Oklo reactor is that even in a region that evidently
>has ground water contact, and there is no care in packaging, it's possible to
>not have migration ofr literally billions of years; it's tough to argue that
>immobilizing the material by vitrification and burial in a desert region with
>no ground water is doomed to failure.

There were several factors involved in the Oklo phenomenon.  The uranium was  
enriched; it was sufficiently concentrated in a small zone; it was sufficiently 
dispersed to allow water to moderate the reaction; and very few neutron poisons 
were present.  The fact is, however, that an atomic pile can still be built with 
natural (unenriched) uranium if the geometry is precisely correct.

It less well established which regions will remain as geologically stable as 
Oklo for eons.

bill kolb
bkolb@arinc.com