Quote - The reactors at Fukushima haven't blown up. But the cooling systems have failed, hence the desperate effort to cool them down with sea water.

If you need to cool something it is because it is hot and is generating heat. If heat was not generated it would be no needs to cool anything. Still today, 16 days later, they still need to cool the reactor, que question is, what is generating heat and which is the heat source ? There are several conceptual misconceptions. First the terms "reactor blown up" or "reactor exploded" are symbolic or metaphoric. A nuclear fission in a reactor never can turn into an explosion, the level of enrichment is too low for an explosion be possible, it only will burn and generate heat. What makes the explosion when it exist can be too much steam pressure that makes the boiler explode, accumulation of hydrogen or other combustible materials that can explode, but never the combustible rods by itself. Another one is the cooling, cooling is also symbolic, you don't need to cool the reactor because it is hot. If the reactor wouldn't be hot it would be impossible to generate electricity. The only existent way for any operational reactor to produce energy is through heat. The direct conversion of fission energy into electricity is only theory, I know it for 50 years and still it continue to be a theory without any practical application. So the only way to produce energy is through heat. The combustible rods become hot, produce heat and the heat is transferred to water or another liquid, water turns into steam and steam moves the turbines, heat energy of the steam is transformed into mechanical energy and is transformed in electricity by the generator. Steam is "cooled" that means that lost it energy in heat form and returns as water into the reactor. Cooling is the process of transferring fission energy to electric energy. And here comes another important point, without water is impossible to exist fission in this kind of reactors. Water has two important functions, is not only for "cooling". One function is to transfer energy (cooling) and the other function is to act as a moderator slowing neutrons. Fission in U235 can only happen with slow neutrons, without water surrounding combustible rods it would not be enough slow neutrons to make fission possible. Throwing water inside a reactor cools the rods, but also makes fission possible. Removing water the rods can become very hot, but all the fission is stopped and so the temperature of the rods will decrease with time. These reactors have by itself a fail-safe design.

Stupidity also evolves!