"Burn up" in power reactors is normally expressed in MWdays/ton.
EG, from what I have read, with a MAGNOX (natural urainium metel) reactor MWD/T is only around 4000. CANDU (also natural uainium) is a bit better at around 7000. (presumably because of better neutron management)
AGR and PWR's (SEU 2-3%) manage nearer 20,000 while designs using highly enriched fuel (90%) can manage 100,000.
(Interestingly from what I have read, FBR deisgns seem to also manage 100,000 despite having enrichments of only around 30%, I guess that this is because the fuel effectivly gets richer during the burn cycle making it more tolerant of poisens)
But what do all these figures represent in terms of the overall %age of available urainium consumed. Both in terms of the reactor operation and in terms of the overall cycle (ie how many tons of DU do you get from producing 1 ton of 3%LEU, or indeed 90%HEU?)
