Why is thorium not used in a nuclear reactor?
Thorium is quite widespread and could be a useful part of the nuclear fuel cycle. It is not itself fissile, but if it is irradiated in a reactor it will produce uranium 233 which is fissile. To separate out the U233 would require processing of irradiated material which is not done on any large scale in the US at the present time. Some countries such as India are interested because they have plenty of thorium and not so much uranium. In the US and Europe supplies of uranium are not a problem and we have the enrichment facilities required to raise the level of U235, so there is no need to go down the thorium route, but I am sure this will be kept under review in the future.
