Uranium ore concentrate can not be used in nuclear reactors; first it must be enriched. Before enrichment, it must be converted into a gaseous form called uranium hexafluoride, or Hex. The majority of commercial conversion plants are located in North America, Europe and Russia. The gaseous Hex is loaded into 48Y steel cylinders (48" in diameter) which solidifies inside the cylinder on cooling to room temperature. Once securely packaged, the cylinders are transported by rail, road and sea to enrichment facilities.