Uranium
Nuclear Fission
The process of splitting the uranium atom to form smaller
atoms is known as 'nuclear fission'. Nuclear fission releases energy.
Rapid release of this energy is the basis of nuclear weapons
.
Controlled release of the energy is used in nuclear reactors
for a variety of purposes.
In a nuclear power station the energy is used to heat
water to produce steam, which turns a turbine to generate
electricity.
One of the most common uses of electricity is to heat water. Nuclear power
is the most inefficient and polluting way of heating water. The most efficient
and cleanest way to heat water is to use
solar energy.
Chain reaction
The release of large amounts of nuclear energy comes from
a chain reaction initiated by nuclear fission.
The U-235 atom has a core (nucleus) that is made up of
92 protons and 143 neutrons. The sum of these two particles is the atomic
number 235, which gives the uranium isotope its name.
When U-235 atoms are bombarded with neutrons their nuclei
split into two parts, at the same time releasing two or three more neutrons.
These neutrons can produce a chain reaction splitting the nuclei of other
U-235 atoms, releasing more energy and more neutrons, and so on.
When operating according to plan, this chain reaction
is controlled in a nuclear reactor.
When faults develop in the control system, as at Three Mile island
(USA, 1979) and Chernobyl
(Ukraine, 1986) the chain reaction gets out of control. Explosions, extreme
fires, and melting of the highly radioactive fuel occur. The molten fuel
is capable of travelling through the base of the reactor (the "China Syndrome").
Fission products
U-235 is radioactive but the products of nuclear fission
of U-235 are infinitely more radioactive. These products becomes high level
radioactive nuclear waste that is extremely
difficult to handle, store and manage safely. The waste remains dangerous
for longer than people have lived in Australia (tens of thousands of years).
Greater technical detail can be found on this topic by searching through
the publications at www.ccsa.asn.au
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© 2002 Conservation Council of SA.
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