Re: Pyrochemical N-waste reprocessing
- From: dezakin@xxxxxxx
- Date: 3 Nov 2006 15:37:27 -0800
Alessio wrote:
Hello.
I'd like to understand what is the actual state of the art of "dry" nuclear
waste reprocessing
systems like pyroprocessing,expecially those who can deal with oxide fuel
(for example at Russian RIAR).What are their efficiency in extracting
actinides,for example U or Pu and MA in/out and their typical
decontamination factors? What their typical size/footprint ? What about
their estimated cost?
Cost is cheap, but inertia of aqueous processing plants is big,
considering they're big government projects. Another problem is that
pyroprocessing methods dont do Pu extraction well, and most
reprocessing plants are tied to MOX fuel production.
My own idea is,instead to re-burn them in fast reactors (see integral fast
reactor program) that are costly to buil and difficult to operate with
multiple recycles (I suppose due to low burn-ups achievable),to burn Pu and
minor actinides in very high burn-up (e.g. > 700 MWg/kg HM),good neutron
economy thermal reactors with only one reprocessing (pyroprocessing) cycle.
Bad idea. Use fluid fuel reactors of some sort, like molten chloride
reactors, to continuously process the fuel for better neutron economy,
as well as better economics over all. Essentially all liquid metal
reactors are economic losers, and IFR itself got way more attention
than it deserved. Good fuel processing process, overhyped uninteresting
reactor.
You fuel the liquid chloride reactor with the Pu and other minor
actinides, and you ship all the uranium back to whoever wants it; Maybe
back to the enrichment plant, or direct for use in CANDUs. Fission
products themselves you separate for sale on the market, with a few kg
of garbage per GW year that no one will be able to use. Its a bit of an
improvement, 100tons to 100kg.
You'll have lots of excess neutrons to play with, so you might just
want to wrap thorium around it and breed U233 for sale as a LWR reactor
fuel or to fuel liquid flouride thorium breeders.
I think that pebble bed reactors developed in South Africa or generally HTGR
based could have these features
http://www.technologyreview.com/read_article.aspx?id=12727&ch=energy
http://web.mit.edu/pebble-bed/Presentation/HTGR.pdf
Huh? PBMR's are interestingly inexpensive, but if you're concerned
about waste processing, they're no good at all. They produce higher
volumes of waste that is more difficult to take apart. Its real waste
advantage is direct disposal to dry storage without a cooldown period.
The best reactor for the future is the liquid flouride reactor.
http://www.thoriumenergy.blogspot.com/
Finally,I found a lot of Authors are really developing this point of
view,i.e.
thermal actinides transmutation versus fast reactors.
http://aaa.nevada.edu/pdffiles/nov1104/leon.pdf
http://www3.inspi.ufl.edu/icapp04/program/abstracts/4038.pdf
http://www.physor2004.anl.gov/PHYSOR%20Program%20(FINAL).pdf (pag.50)
A big question I know,but I'd appreciate any comments,
suggestions or opinions. Thanks.
Check out molten salt breeder reactors. They'll do everything you want
for cheaper with less infrastructure, safer and better thermodynamic
efficiency than any other reactor regime.
.
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