this has possibly more accurate resource data on thorium
Thorium in Australia which suggests Australia, USA, Turkey, India, Venezuela
as the prime countries. However the problem is going to be the interlinking of the two markets: extracting thorium without extracting the rare earths doesn't make commercial sense - at present. And the Chinese totally control the rare earths market.
Given the environmental issues, Australia and the USA may simply be too expensive due to the effluent volumes