Uranium

Uranium that comes from nature is mostly composed of two types (isotopes) called 235 and 238. The 235 is the good stuff but only represents .7% while the 238 is 99.3%. In order to operate a power plant the 235 must be enriched to 5%. This is done by changing it to a gas called uranium hexafloride and spinning it around in a centrifuge. This takes time and money and most of this is done in Russia. At this point Russia is still shipping this product to users around the world. As a side point this enrichment process is what used to make uranium suitable for bombs but the process is not linear. For example it takes just as much time to get one to five percent as it does to get from five to 93% which is what is needed for a bomb. One of the many advantages of using thorium instead of uranium is that you can skip the enrichment process. Using thorium would remove Russia from the supply chain.