Cold fusion

Cold fusion is a type of nuclear reaction that occurs at, or near, room temperature. It would contrast starkly with the nuclear fusion that takes place naturally within stars and artificially in hydrogen bombs and prototype fusion reactors under immense pressure and at temperatures of millions of degrees, and be distinguished from muon-catalyzed fusion.

The early reactors used low-energy nuclear reactions (LENR) or condensed matter nuclear science (CMNS).

This was a key technology to move towards Type II and beyond.