|Principal characteristics of the six types of Generation IV reactors:|
Acronyms of the six types of Generation IV reactors, along with the type of neutrons used - fast or thermal (slow) and of fuel cycle. In a closed cycle the fuel is reprocessed and reused - which ensures a far greater efficiency. For simpler, open cycles, the fuel passes through a reactor only once. The dates shown above indicate the dates by which the prototypes could be up and running.