These are gas-cooled reactors, and much lower power output. Existing designs for Navy reactors are all pressurized water reactors that produce hundreds of MW.

These are gas-cooled reactors, and much lower power output. Existing designs for Navy reactors are all pressurized water reactors that produce hundreds of MW. There's also a challenge in waste heat. Ships have basically unlimited seawater, but they are probably designing this to use minimal (or no?) water.