[ RadSafe ] Highly Enriched Fuel Reactors
gstanford at aya.yale.edu
Sat May 18 23:22:55 CDT 2013
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
At 04:07 PM 5/18/2013, David Lee wrote:
>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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