Vorrei capire qual'� limite max che si pu� (realisticamente) ottenere nei
rapporti di conversione in reattori alimentati al solo uranio
arricchito,piccolo o grande che sia tale arricchimento.In un ng in lingua
inglese avevo gi� formulato una domanda del tipo che,se permettete,si
incollo (perdonate il mio inglese)
Giusto per non ripetere cose gi� dette o note,vi dico che sono gi� al
corrente del fatto che si pu� realizzare l'autofertilizzazione (cio� la
produzione di pi� fissile di quello che si consuma) con neutroni termici con
il ciclo uranio-torio o in campo veloce con quello uranio-plutonio.La mia
domanda verte invece sui cicli al solo uranio,debolmente o altamente
arricchito
Incollo di seguito la domanda (la mail in allegato � valida per qualsiasi
risposta):
Extract from wikipedia:
http://en.wikipedia.org/wiki/Breeder_reactor
" All commercial Light Water Reactors breed fuel, they just have breeding
ratios that are very low compared to machines traditionally considered
"breeders." In recent years, the commercial power industry has been
emphasizing high-burnup fuels, which are typically enriched to higher
percentages of U235 than standard reactor fuels so that they last longer in
the reactor core. As burnup increases, a higher percentage of the total
power produced in a reactor is due to the fuel bred inside the reactor.
At a burnup of 30,000 Gigawatt days/ton heavy metal, about thirty percent of
the total energy released comes from bred plutonium. At 40,000 Gigawatt
days/ton heavy metal, that percentage increases to about forty percent. This
corresponds to a breeding ratio for these reactors of about 0.4 to 0.5.
Namely, about half of the fissile fuel in these reactors is bred there. [5]
This is of interest largely due to the fact that next-generation reactors
such as the European Pressurized Reactor and AP-1000 are designed to achieve
very high burnup.[6] This directly translates to higher breeding ratios.
Current commercial power reactors have achieved breeding ratios of roughly
0.55, and next-generation designs like the AP-1000 and EPR should have
breeding ratios of 0.7 to 0.8, meaning that they produce 70 to 80 percent as
much fuel as they consume..."
If I understood correctly,we can achieve with LEU in LWR higher conversion
factors with higher burn-ups,although perhaps not breeding
Now,I know it is possible to achieve breeding in thermal spectrum with
thorium as fertile element and with uranium 238 only in a fast spectrum;my
question is: is it possible to achieve breeding or at least high conversion
factors (near breeding) with enriched uranium in high burn-up thermal
reactors (no thorium blanket)?
This is an important feature,given the fact that not only new generation of
LWR like AP-1000 or EPR use more enriched uranium (so higher burn-ups),but
for example PBMR achieves burn-ups in the order of 100 GWd per HM tonne.In
that case,which could be a typical conversion factor?
Clearly,I supposed that in conversion factor definition we include plutonium
fissile isotopes generated and fissionated in situ,not only that present in
the fuel at discharge
Received on Sun Dec 03 2006 - 12:36:19 CET