When Fuel rods melt....

When
fuel rods melt

In
a meltdown, it comes to physical processes that are unstoppable. The end is an
explosion. The consequences for humans and the environment are devastating. Cause
of the melt is usually a failure of the cooling system.

In
a core melt overheat the fuel rods of a nuclear reactor - so much so that they
can liquefy and turn into an uncontrollable, radioactive melt. The consequences
are difficult to calculate: A up to 2000 degrees C hot mixture of fissile
material and metal can eat through the protective shell of the reactor core and
into the environment. Also possible are violent explosions. "In the coming
meltdown of physical processes that are unstoppable," said Greenpeace
nuclear expert Tobias Muenchmeyer.

Cause
of the meltdown is always a failure of the reactor cooling system. The
temperatures rise in the fuel rods containing uranium or uranium-plutonium
mixtures at irresistibly. At the end of the radioactive materials as well as
melt the steel fuel rod casings and fall to the bottom of the reactor vessel. The
evaporated water used for cooling and is separated by heat into hydrogen and
oxygen. Both substances are known as explosive hydrogen-oxygen mixtures, which
can lead to explosions with immense force.

Although
nuclear power stations around the reactor vessel includes a further protective
coating of steel or reinforced concrete, the so-called containment. But even
that can be destroyed by explosions or broken by the extremely hot atomic soup.
keep the nuclear experts as critical medical organization IPPNW it difficult to
imagine that current nuclear power plant containment can withstand the enormous
stresses during a core melt accident actually.

The
consequences for humans and the environment during a meltdown would be devastating:
the molten reactor contents is among other things of highly radioactive uranium
and the extremely bright, highly toxic plutonium - one of the most dangerous
substances known. There are also various other radioactive isotopes such as
cesium 137, which is formed during reactor operation in the interior of the
kiln. These substances would spread by an explosion in the ambient air or melt
with the meltdown of the protective container in the ground floor. In the
nuclear disaster at Chernobyl in 1986 large quantities of cesium 137 were
released, which came to northern and western Europe, deposited on fields and
pastures, and there came into the human food chain.