After a two-year design-maturation period, one of the three companies may be selected to build and demonstrate a prototype.

They want a system that can be safely and rapidly moved by road, rail, sea or air and for quick set up and shut down, with a design which is inherently safe.

On 9 March 2020, the three development contracts were:

BWX Technologies, of Virginia, for $13.5 million;
Westinghouse Government Services of Washington, D.C. for $11.95 million; and
X-energy of Maryland, for $14.3 million.

The goal is for small nuclear micro-reactor in the 1-5 megawatt (MWe) power range.

China is starting up a 210 MWe HTR-PM pebble bed reactor this year. They used pebble technology from Germany.