Engineering360: "US Army Janus program selects 5 nuclear microreactors"

The word "advanced" is used loosely in describing reactor operating systems. Do they mean Gen III using water cooled thermal technology; or do they mean a Gen IV (fast) reactor using a fast neutron spectrum? Since at least one was liquid metal cooled, at least that one is a fast reactor. I hope all are, because fast reactors are much more efficient in the use of uranium.

Looked into this a little more to find out a bit more about the energy reactions. It appears they are neither Gen III or Gen IV but are a new design that run on thermal neutron spectrum. All but the General Atomics microreactor uses TRISO particle fuel, General Atomics uses the UZrH fuel.