Why did the reactors at the Fukushima plant overheat?
Without injections of coolant, water temperatures and water pressure started rising inside the reactors. There were fires and explosions. The intense heat started boiling away the coolant in the reactor core.
Still after reading some information, Im still have difficulty understanding.
Nuclear reactors need to be cooled down.
"the earthquake and tsunami knocked out the site's main electrical power supply and backup generators, making it hard to cool the nuclear fuel rods in the reactors and the cooling ponds nearby."
http://news.cnet.com/8301-30685_3-20043686-264.html
Oh that's from the article, that's how the problem came about? They heated because of the earthquake and tsunami?
They overheated because the nuclear plants lost power -- no electricity!
The reactors at the Fukushima Daiichi nuclear power plant overheated due to a combination of factors arising from a massive tsunami that hit the site on March 11, 2011. The earthquake that struck off the coast of Japan caused a power failure, disabling the cooling systems of the reactors. Without cooling, the nuclear fuel began to generate heat, resulting in a partial meltdown of the cores.
To understand this better, it is important to recognize the primary role of cooling systems in nuclear reactors. Nuclear reactors generate heat as a result of nuclear fission, which must be continuously removed to maintain a stable operating temperature. Cooling systems, typically relying on a continuous flow of water, transfer this heat away from the reactor core.
In the case of the Fukushima plant, the earthquake caused a loss of off-site power, which led to a failure in the primary and backup cooling systems. Additionally, the tsunami that followed the earthquake resulted in flooding, damaging the backup generators that were meant to provide power for the cooling systems.
Without functioning cooling systems, the heat from the fuel could not be adequately dissipated, leading to an increase in temperature. This ultimately caused the fuel to melt, leading to a partial meltdown and the release of radioactive materials.
Therefore, the overheating of the reactors at the Fukushima plant was a result of the combination of the loss of both primary and backup cooling systems due to the earthquake and the subsequent flooding from the tsunami.