For getting an intuition on it, I would recommend the clip from HBO’s Chornobyl which ELI5’s a nuclear meltdown. [1]
If the reactor is air cooled, that can be translated as “the heat can just burn off” as there isn’t a liquid cooling system, reducing this failure mode.
As mentioned in the video, reactions are about balance. If a ‘safe’ SMR gets shut off or has its systems fail, you would want the accelerators / enablers of the reaction to disappear, and roll out the reaction.
This is unlike most fission reactors in use today which are a ‘balanced dance’ where lots of the design is focused on reducing the speed of the burn (like a constant stream of water on a fire) rather than say controlling the oxygen of a fire with limited fuel. SMRs aim be more of the “control the oxygen” type of reaction rather than “keep the fire cool” kind of reaction. (Forgive my vast oversimplification, but this is my intuition on it).
If the reactor is air cooled, that can be translated as “the heat can just burn off” as there isn’t a liquid cooling system, reducing this failure mode.
As mentioned in the video, reactions are about balance. If a ‘safe’ SMR gets shut off or has its systems fail, you would want the accelerators / enablers of the reaction to disappear, and roll out the reaction.
This is unlike most fission reactors in use today which are a ‘balanced dance’ where lots of the design is focused on reducing the speed of the burn (like a constant stream of water on a fire) rather than say controlling the oxygen of a fire with limited fuel. SMRs aim be more of the “control the oxygen” type of reaction rather than “keep the fire cool” kind of reaction. (Forgive my vast oversimplification, but this is my intuition on it).
[1] https://youtu.be/TmIEI4ky-Zc