What caused the hydrogen generation and explosions in the Fukushima Daiichi nuclear power plants in 2011?

The spent fuel pool of previously shut down Reactor 4 increased in temperature on 15 March due to decay heat from newly added spent fuel rods, but did not boil down sufficiently to expose the fuel.

What can cause hydrogen to explode?

Hydrogen gas is very flammable. This is why the balloon filled with hydrogen ignites. The heat given off by the candle provides the activation energy required for the reaction that produces water from hydrogen and oxygen. This reaction is highly exothermic, producing the prodigious explosion.

What damaged the back up generators leading to the Fukushima Daiichi nuclear reactor accident?

Wake-up call During the 2011 disaster, tsunami heights reached an estimated 13 meters at Fukushimi Daiichi — high enough to flood all of the backup generators and wash away power lines.

Which reactor exploded in Fukushima?

reactor 1-4
Nuclear Power Plant Explosions at Fukushima-Daiichi☆ The station blackout and loss of all instrumentation and control systems at reactor 1-4 at Fukushima Daiichi nuclear power plant caused the loss of control and cooling means of three reactor units that were operational up to the time of the earthquake.

What caused the Fukushima meltdown?

Following a major earthquake, a 15-metre tsunami disabled the power supply and cooling of three Fukushima Daiichi reactors, causing a nuclear accident beginning on 11 March 2011.

What causes a nuclear meltdown?

A meltdown may be caused by a loss of coolant, loss of coolant pressure, or low coolant flow rate or be the result of a criticality excursion in which the reactor is operated at a power level that exceeds its design limits. Alternatively, an external fire may endanger the core, leading to a meltdown.

Did Fukushima explode?

Workers rushed to restore power, but in the days that followed the nuclear fuel in three of the reactors overheated and partly melted the cores – something known as a nuclear meltdown. The plant also suffered a number of chemical explosions which badly damaged the buildings.