From the Kairos Power Website who is actively trying to develop these for commercial use:
"...The Kairos Power FHR (KP-FHR) is a novel advanced reactor technology that leverages TRISO fuel in pebble form combined with a low-pressure fluoride salt coolant. The technology uses an efficient and flexible steam cycle to convert heat from fission into electricity and to complement renewable energy sources..."
I believe this is fully the way to go, but I need more specifics.
This graphic is from their website: 
First, it appears to be a "pebble bed" design which is inherently far, far safer. In this configuration, in their words: "...AUTOMATIC SAFE SHUTDOWN; PASSIVE COOLING UPON LOSS OF POWER..."
Secondly, it is using a low-pressure "fluoride salt coolant" which I don't fully know what that entails. The USA made reactors cooled with liquid Sodium, and because it can explode when exposed to water, it resulted in explosions during maintenance processes that became so frequent that they stopped calling the fire department when it happened in an earlier experimental plant if my memory serves me correctly. We built a submarine, the second nuclear submarine built at the time the USS Nautilus was (USS Seawolf) but it was difficult to maintain, and Admiral Rickover was fundamentally opposed to them.
Using these types of reactors as "breeder reactors" running on Thorium could produce more fuel than they consumed, but the technology could not be wrangled into practical use back then, and sadly, we gave up on it. Salt Cooled reactors were difficult to figure out, and we went with Boiling Water and Pressurized Water Reactors.
In this type of reactor being designed by Kairos, the fuel is contained in spheres called "pebbles" which can be monitored and replaced in a fully automated and safe way when their heat level drops due to lower isotopic action.
The isotopes are encased in indestructible spheres, so the danger of contamination is nearly zero, they will never achieve criticality (fission) in the way a conventional nuclear plant could. They produce heat, but an uncontrolled release is not likely, even if the small plant is hit by a bomb. The "pebbles" could be send out for recycling.
I am all in on this. This is the way we should be going. Smaller units that can power a town or city by municipal power. We should have been pursuing this decades ago.
I will be honest, my knowledge is a bit dated and I am going off memory here, so I hope others who understand this more clearly will chime in.