1,187,188. Transmutation of elements. ATOMIC ENERGY OF CANADA Ltd. 31 Oct., 1968 [20 March, 1968], No. 51716/68. Heading G6P. In a process for the conversion of thorium 232 into uranium 233 by neutron irradiation, thorium oxide is positioned in an intense thermal neutron beam for a short period. The thorium 232 captures neutrons and is converted to thorium 233 which decays by a radio-active beta decay having a half life of 22À4 minutes to protoactinium 233. Irradiation is stopped and the protoactinium 233 decays by radioactive beta decay, half life 27 days, to fissile uranium 233. A portion of the protoactinium 233 produced during the irradiation captures neutrons and is converted to protoactinium 234 which decays to fertile uranium 234. Fissile 235 is also formed, by neutron capture, from the uranium 234.