>>2305341might want to explain this pic for those who don't get it, but basically in the event of a meltdown or runaway criticality those ice plugs at the bottom there melt, and the molten fuel falls into the dump tanks. Once the fuel is in the dump tanks it's no longer densely packed enough to sustain fission, and the reaction immediately stops.
In older designs (like 3 mile island or chernobyl) the fuel mixture must be kept cool and the reaction rate dampened by control rods (they absorb neutrons, slowing down the reaction). If the cooling system fails, the fuel is allowed to heat up, increasing the reaction rate, which causes it to heat up more, and so and so on. Fukushima was like this, the tsunami knocked out the cooling pumps, and the rest is history. the design in parent's post would have 100% prevented fukushima, 3mile island, and chernobyl.
nuclear is one of those rare technologies where failures are seen as a "omg stop using this NOW!" event versus "okay, that was a mistake, our next iteration will be better" but by throwing the baby out with the bathwater europe is now even more dependent on coal and russian energy exports. Luckily the US hasn't abandoned nuclear yet, but we've foolishly stopped making new, safer reactors due to greenies doing what they do best (being retarded); and so the reactors that are still out there are of the older, unsafe designs.
