The Terrestrial Energy Integrated Molten Salt Reactor and a supercritical CO2 turbine are both under development and should be commercially ready in about ten years

. One interesting aspect is that
they have far higher power density. They would enable a reactor and
turbine that is about 50 times more power dense than the ones that are
currently in nuclear submarines.
http://nextbigfuture.com/2013/12/molten-salt-reactor-about-50-times.html

http://nextbigfuture.com/2013/12/could-molten-salt-reactor-be-power.html