When the accident at Fukushima happened, the temperatures in the reactor vessels increased and the pressures went up. In order to deal with this, steam was released from the pressure vessels. Water boiling in the reactors exposed the fuel rods, and since the zircaloy cladding of the rods reacts with steam, producing hydrogen, this reaction is the most likely source. This situation is, of course, a meltdown.
The problem with the hydrogen, of course, was that it collected in the reactor buildings, mixed with the atmosphere, and exploded.
Fukushima
There are two Fukushima nuclear power plants, both of which are in the Fukushima district on the east coast. Fukushima Daiichi, where the meltdowns happened, is at a town called Okuma. Fukushima Daini, is at a town called Naraha.
Rila Fukushima is 5' 8".
Fukushima Incident happened in 1882.
Kikujirō Fukushima was born in 1921.
Fukushima University was created in 1949.
Fukushima College was created in 1941.
Yutaka Fukushima was born in 1958.
Fukushima Prefecture's population is 2,028,752.
Naoshi Fukushima died in 2003.
Naoshi Fukushima was born in 1925.
Glen Fukushima was born in 1949.