Out of interest and relating to the previous post on thorium power, this graph uses Google's Ngram Viewer to plot the use of the word thorium.
At one time it was used for gas mantles, which I assume accounts for the ragged peak from about 1900.
Next there is another peak of interest from just after World War II until about 1960. The unsuitability of thorium for nuclear weapons then led to a sharp decline.
Maybe it will pick up again.