TerraPower, the nuclear energy developer founded by Bill Gates, closed a $750 million equity raise, the company said Monday.

Why it matters: TerraPower is among the handful of companies racing to build a small modular reactor and other nuclear technologies, including "nuclear medicine."

The details: Bill Gates co-led the round, along with the South Korean holding company SK Inc. and its sister company, SK Innovation, an energy conglomerate.

Zoom out: TerraPower is building a $4 billion, 345-MW demonstration reactor at a former coal-fired power station in Wyoming.

Catch up fast: SMRs typically generate up to around 300 MW, about a third of the electricity of a traditional nuclear plant.