[ RadSafe ] Article on Wired on Thorium reactors

[John Andrews]

As I recall, the Fort St. Vrain HTGR built by General Atomic used 
thorium as well as urainium as fuel.  Peach Bottom I, on the other hand 
used only uranium and I think that was about 20% enriched.  The main 
problem with Ft. St. Vrain was that the fuel blocks actually floated in 
the high pressure relatively viscous helium used as the coolant.  This 
made it hard to control and it was ultimately shut down.  I am still a 
big fan of the HTGR  reactor from a health physics standpoint.  
Radiation levels during operation of Peach Bottom were very low.  
Decommissioning was a piece of cake, but it is only in mothballs, so 
there is still more work to be done.  FSV was also easily decommissioned 
and radiation levels were low except inside the reactor vessel which got 
a little out of hand when filled with water for shielding that got very 
murky with graphite.  The spent fuel from FSV is still in storage I 
believe.  Fuel recovery is based on burning the graphite and 
mechanically separating the different sized coated particles of thorium 
and uranium before chemical reprocessing.  The dry handling of really 
hot stuff can be difficult if you can't go in and bang on it with a 
hammer...

It was an interesting time...

My boss was not happy when I suggested that we weigh the workers before 
and after to see if they had ingested thorium.  The quantities are quite 
large in terms of mass.

John Andrews, Knoxville, Tennessee




Minnema, Douglas wrote:

>Jaro and Franz,
>
>My recollection is that supposedly India had worked on thorium-based
>reactors, probably in the 1960's or 1970's, since they had a lot of it
>around.  I don't think they still use them today, probably somebody else
>here knows better.
>
>As for U-233 in weapons, it's probably been tested somewhere in the world.
>But the big problem is that the high gamma radiation levels emitted by the
>U-233 makes storage and handling of the material and the devices very
>problematic.  Much more so than other alternatives.  Not good if you want to
>build a lasting stockpile and deploy them conventionally.
>
>Doug Minnema
>
>  
>