Gen IV (Generation IV) is the term used to describe the possible designs of future commercial nuclear reactors that are currently under investigation in order to deliver significant advances in safety, efficiency, sustainability and economics. There are six different Gen IV technologies in development: gas-cooled fast reactors; lead-cooled fast reactors; molten salt reactors (there are two different variations of this technology); sodium-cooled fast reactors; supercritical water-cooled reactors; and very-high-temperature gas reactors.

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