Environment & Energy

The ANEEL fuel intended to burn thorium in Candus needs HALEU at 12 to 20% fissile as a starter for each fuel bundle (or equivalent concentration of plutonium), and will not be a true breeder, with conversion ratios below 1.0. CopAtomx should get much better neutron economy even than a Candu -
1/ there's no xenon 135 in the core, it's rapidly outgassed from the salt, just from vapour pressure, at 700 C
2/ Unlike with an ANEEL fuel bundle, there's no high neutron cross section protactinium in the core (it's all in the blanket, and with the thorium to protactinium ratio there at about 1000 to one, parasitic neutron losses should be low)
3/ the spherical core geometry, with heavy water inside and around it, and a breeding blanket round that, minimises leakage.
CA claim they can breed with 5% LEU (or equivalent in transuranics), at about 1.1 breeding ratio once they fully convert to U233, and so grow more quickly than a fast reactor fleet. If they fail, there are plenty of fast neutron contenders - Russia's BREST 300 and BN1200, Newcleo in France and Italy, Terrapower's Natrium in Wyoming, Blykalla in Sweden - but thermal spectrum reactors so far have had a better operational record. Maybe even Japan's reduced moderation boiling water concept could breed ... but nobody's working on that, CA have hardware nearly ready for low power fission testing.