Enriched uranium use in heavy water reactors
Alessandro
natural uranium in nuclear reactors with no enrichment (and only heavy water
the use of NU as dioxide). But the use of enriched uranium is NOT forbidden
in Candu kind reactors,instead it improves neutron and fuel economy.
I found this data about the use of enriched uranium in Hwr:
with uranium enriched at 1,7% uranium is discharged at a burn-up of 32
MWd/kg;
'' '' '' '' 1,2% '' ''
'' 22,5 ''
'' '' 0,83% '' ''
'' 12,5 ''
with natural uranium (0,71%) current Hwr has a bup of 7,5/7,9 MWd
per kg
In the first case (1,7%) a kg of natural uranium produces 76 thousands kWh
vs 45 thousands kWh wirh current Lwr fleet,about 70% more
http://kutuphane.taek.gov.tr/internet_tarama/dosyalar/cd/3881/Nuclear/Nuclear-11.PDF
http://www-pub.iaea.org/MTCD/publications/PDF/csp_006c/PDF-Files/paper-10.pdf
So,why nobody goes ahead with this strategy,i.e. the use of sligtly enriched
uranium in heavy water reactors,including recycling of the enriched uranium
discarged from other kind of reactors - moreover,in the future new reactors
will use more enriched uranium until 10% and discharge more usefull uranium
for recycling,for example South African pebble bed reactors discharge
uranium at an enrichment more than 1,8% after a bup of about 100 MWd/kg
(that equivales to 51'000 kWh per kg of NU in a once through cycle)
Alessandro
"Alessandro" <I...@NOSPAM.IT> ha scritto nel messaggio
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I forgot,of course I know that discharged uranium has a lot of impurites and
neutron absorber like uranium 236,so it has a lower quality than natural
uranium even with the same enrichment
dave.w...@comcast.net
> "Alessandro" <I...@NOSPAM.IT> ha scritto nel messaggionews:qH7Ph.33457$6.3...@tornado.fastwebnet.it...
>
>
>
>
>
> > Heavy water and graphite are the only material that allow the use of
> > natural uranium in nuclear reactors with no enrichment (and only heavy
> > water the use of NU as dioxide). But the use of enriched uranium is NOT
> > forbidden in Candu kind reactors,instead it improves neutron and fuel
> > economy.
> > I found this data about the use of enriched uranium in Hwr:
> > with uranium enriched at 1,7% uranium is discharged at a burn-up of 32
> > MWd/kg;
> > '' '' '' '' 1,2% '' '' ''
> > 22,5 ''
> > '' '' 0,83% '' '' ''
> > 12,5 ''
> > with natural uranium (0,71%) current Hwr has a bup of 7,5/7,9 MWd
> > per kg
>
> > In the first case (1,7%) a kg of natural uranium produces 76 thousands
> > kWh vs 45 thousands kWh wirh current Lwr fleet,about 70% more
> >http://www-pub.iaea.org/MTCD/publications/PDF/csp_006c/PDF-Files/pape...
>
> > So,why nobody goes ahead with this strategy,i.e. the use of sligtly
> > enriched uranium in heavy water reactors,including recycling of the
> > enriched uranium discarged from other kind of reactors - moreover,in the
> > future new reactors will use more enriched uranium until 10% and discharge
> > more usefull uranium for recycling,for example South African pebble bed
> > reactors discharge uranium at an enrichment more than 1,8% after a bup of
> > about 100 MWd/kg (that equivales to 51'000 kWh per kg of NU in a once
> > through cycle)
>
> I forgot,of course I know that discharged uranium has a lot of impurites and
> neutron absorber like uranium 236,so it has a lower quality than natural
>
> - Show quoted text -
I suspect this is the future. Various LWR's are also upping their BUP
rate a lot, becoming more and more efficient. Martime PWRs, for
example, only need refueling once every 13 to 20 years! The idea is
that commerically we are talking 15 to 30 years "nuclear batteries"
for smaller units and increasing higher and higher (with breeding) in
"standard" Gen III+ reactors.
I still want to see fuel get up to $350lbs so money will start flowing
into these newer designs.
David
Alessandro
<dave.w...@comcast.net> ha scritto nel messaggio
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I don't understand if there are particular economic or technologic drawbacks
in using (or better recycling from high enriched uranium reactors until the
level of 10% as explained above) Seu in Hwr reactors,I mean,in terms of
safety.Maybe high positive temp coefficients or what?
dave.w...@comcast.net
> <dave.walt...@comcast.net> ha scritto nel messaggionews:1175265511.1...@n59g2000hsh.googlegroups.com...
>
> - Show quoted text -
"Generally speaking", all reprocessing is more expensive than
processing from raw uranium. All these reactor will need SOME
processed uranium if they are going to use thorium, for example. (u235
or pu235 whatever). Is this what you are asking?
D.
Alessandro
Not really,I simply meant using sligtly enriched uranium in current Candu
fleet (or, but only in the future,recycled it from Lwr reactors)
Matthew Beasley
"Alessandro" <I...@NOSPAM.IT> wrote in message
news:qH7Ph.33457$6.3...@tornado.fastwebnet.it...
> So,why nobody goes ahead with this strategy,i.e. the use of sligtly
> enriched uranium in heavy water reactors,including recycling of the
> enriched uranium discarged from other kind of reactors - moreover,in the
> future new reactors will use more enriched uranium until 10% and discharge
> more usefull uranium for recycling,for example South African pebble bed
> reactors discharge uranium at an enrichment more than 1,8% after a bup of
> about 100 MWd/kg (that equivales to 51'000 kWh per kg of NU in a once
> through cycle)
>
It's being considered by South Korea
http://www.thestar.com/article/180615
Alessandro
"Matthew Beasley" <nos...@spam.com> ha scritto nel messaggio
news:HSfPh.1821$mL5...@news.cpqcorp.net...
They don't explain which uranium enrichment level use and which burn-up
achieve,I think these are the most important points
daestrom
Perhaps as Dave is trying to point out, it is because manufacturing fuel
from raw uranium ore and not enriching it at all is cheaper than trying to
reprocess 'slightly enriched' spent fuel.
Only when the cost of new fuel processing from ore to fuel assembly rises
above that of reprocessing spent fuel, will this become practical.
daestrom
Alessandro
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ha scritto nel messaggio
news:460fc0b5$0$17218$4c36...@roadrunner.com...
>>> "Generally speaking", all reprocessing is more expensive than
>>> processing from raw uranium. All these reactor will need SOME
>>> processed uranium if they are going to use thorium, for example. (u235
>>> or pu235 whatever). Is this what you are asking?
>>>
>>> D.
>>
>> Not really,I simply meant using sligtly enriched uranium in current Candu
>> fleet (or, but only in the future,recycled it from Lwr reactors)
>>
>
> Perhaps as Dave is trying to point out, it is because manufacturing fuel
> from raw uranium ore and not enriching it at all is cheaper than trying to
> reprocess 'slightly enriched' spent fuel.
>
> Only when the cost of new fuel processing from ore to fuel assembly rises
> above that of reprocessing spent fuel, will this become practical.
>
> daestrom
But just curious,recycling Lwr spent fuel or Dupic cycle aside,what's the
problem in using Seu in existing Hwr?It improves uranium fuel economy (32
MWd/kg at 1,7% vs 7,5-8 MWd/kg with natural uranium?Are there any particular
safety issues,for example overcriticality?