What is a meltdown at a nuclear power plant?

Answer 1

A partial meltdown is a term for a type of severe nuclear reactor accident. In this situation, the cooling and safety systems of a reactor have failed to the point where the core overheats severely. In this instance, the nuclear fuel, which is welded inside tubes or plates, becomes so hot that it melts its way through the metal (called cladding) encasing it. This contaminates the whole reactor with highly radioactive material. A partial meltdown is generally contaned within the reactor vessel or the containment structure. But the reactor and associated cooling systems will end up highly contaminated with radioactive materials and be unusable.

Answer 2

There is no such thing as a blast radius of a meltdown, provided it is contained in the reactor pressure vessel. If the vessel bursts, then it's another matter, but it is most likely to crack and relieve pressure that way, so very unlikely to produce a blast.

Answer 3

A meltdown is when the uranium or plutonium fuel burns through the zirconium oxide outer layer of the fuel rod and melts down into a pool of molten radioactive material in the bottom of the reactor chamber until it burns through the reactor vessel and the ground until it hits the water table when it explodes in a cloud of radioactive material into the atmosphere and scatters all around the world.

Answer 4

Fukushima Daiichi had a partial meltdown in consequence to the tsunami of March 2011 in Japan.