Thorium was tested in the 60's and worked very well indeed. Problem isn't the technology but the financial backers preferring the mainstream product to anything remotely unusual.
The situation with cold fusion (LENR) is rather perplexing, after all if the results are as good as claimed then why isn't it already in commercial production? I suspect because although positive results have been had, replicating them reliably has proved difficult. Other thing is that many labs won't work on it because it's too controversial. It may well be the real game changer though once it's fully understood.