The Rising Influence of Rising Affluence

[OakesCS]

as the 2nd link points out near the bottom, thorium fueled reactors have been around for several decades. Towards the end of the cold war and after, these were promoted as a good way to get rid of Pu stockpiles. Between cheaper alternatives and nuclear accidents, reactors which can burn Th never caught on. Some of it was just really bad timing. I don't think the technical barriers are as problematic as the article seems to imply.

Your 3rd link is semi-ancient and seems to focus on REEs and the Mountain Pass deposit which Chevron briefly owned through Unocal (although Chevron did have some interest in Mtn Pass back in the 1980s).