/johnny
[ Thorium reactors are supposed to be much safer in that regard. Google TechTalks on YouTube has a good presentation on that. ]
Liquid Thorium Fluoride Salt Reactors. We have a winner.
The Liquid reactants are held in the core by use of a “Frost Plug” when the power dies the active cooling to the frost plug ends and the liquid reactants flow via gravity into a baffled drain tank where they solidify and become inert. Since the liquid fuel is bound ionically to the most reactive halogen ie. Florine they will not react with Oxygen meaning fire risk is drastically reduced.