The United States produced, over the course of the Cold War, approximately 2 metric tons of uranium-233, in varying levels of chemical and isotopic purity.
2.
It is most often sold in various grades of purity, from 98 % enrichment to 99.75 99.98 % deuterium enrichment ( nuclear reactor grade ) and occasionally even higher isotopic purity.
3.
Some isotopically purified elements are used in smaller quantities for specialist applications, especially in the semiconductor industry, where purified silicon is used to improve crystal structure and thermal conductivity, and carbon with greater isotopic purity to make diamonds with greater thermal conductivity.