[ RadSafe ] Highly Enriched Fuel Reactors

[George Stanford]

Guys:

      Regardless of reactor type, you get approximately 1 ton of 
fission products for each GWe-yr of energy.  Most of the activity for 
the first couple of centuries is due to Cs-137 & Sr-90.  If a 1-GWe 
TWR runs for 60 years, it will accumulate 60 tons of fission 
products, and only about half of the created Cs & Sr will have decayed by then.

      As Jaro says, uranium with enrichment below 20% is considered LEU.

      The TWR publicity that I've seen says that the uranium 
utilization will be between 40 and 50 times that of the LWR (which is 
considerably less than 1%).  Thus the TWR (as currently planned) 
would use less than 50% of the energy that was in the original 
ore.  Because of the length of time the residual transuranics have 
been exposed to the neutron fluence, recycling the used fuel after 60 
years would be difficult because of built-up alpha activity -- 
perhaps too difficult to be feasible.

       Consider a 1-GWe TWR.  After 60 years of operation it will 
have produced 60 tons of fission products and will still contain more 
than 60 tons of unused uranium, along with probably a few tons of 
long-lived transuranic actinides -- so its initial fuel loading had 
to contain more than 120 tons of heavy metal.  It will not solve the 
waste problem, but it will kick it 60 years down the road.

      In comparison, the same size IFR  with recycling has a core 
about one-tenth the size, and after 60 years will also have produced 
60 tons of fission products, disposed of at he rate of one ton per 
year.  And, with close to 100% utilization of the uranium, the waste 
will contain
little else.

      -- George

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

At 04:07 PM 5/18/2013, David Lee wrote:
>Joe,
>
>I think, I may be wrong, I was once ;-)
>It all depends on how deep you burn the fuel.
>Deeper better, more energy output, less fragments to deal with.
>Some one, please, correct me if I am wrong.
>
>
>On Sat, May 18, 2013 at 1:58 PM, <JPreisig at aol.com> wrote:
>
> > Hey All,
> >
> >      So, with these TWR's and other highly enriched  fuel reactors, with
> > significant use of the fuel, the Cs-137, Sr-90 (i.e. Fission  Fragment)
> > radiation will build up quite quickly.  This will be a challenge  for
> > Health
> > Physicists, Nuclear Engineers at such reactors.  Sounds like  fun.  Neutron
> > production will increase considerably also.
> >
> >     Have a good week.
> >
> >     Joe Preisig
> >
> > PS  I wonder if the bug zapper could be tuned up for tse tse  flies......
> >
> >
> >
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