|
The Energy Story
Nuclear Energy - Fission and Fusion
Another major form of energy is nuclear energy, the energy that is trapped
inside each atom. One of the laws of the universe is that matter and energy
can't be created nor destroyed. But they can be changed in form.
Matter can be changed into energy. The famous scientist Albert Einstein
created the mathematical formula that explains this. It is:
E = mc2
This equation says:
E [energy] equals m [mass] times c2 [c stands for the speed of light. c2
means c times c, or the speed of light raised to the second power -- or c-
squared.]
Scientists used Einstein's famous equation as the key to unlock atomic
energy and also create atomic bombs.
The ancient Greeks said the smallest part of nature is an atom. But they
did not know 2,000 years ago about nature's even smaller parts.
Atoms are made up of smaller particles -- a nucleus of protons and
neutrons, surrounded by electrons which swirl around the nucleus much like
the earth revolves around the sun.
Nuclear Fission
An atom's nucleus can be split apart. When this is done, a tremendous
amount of energy is released. The energy is both heat and light energy.
This energy, when let out slowly, can be harnessed to generate electricity.
When it is let out all at once, it makes a tremendous explosion in an
atomic bomb. The word fission means to split apart.
A nuclear power plant (like Diablo Canyon Nuclear Plant shown on the right)
uses uranium as a "fuel." Uranium is an element that is dug out of the
ground many places around the world. It is processed into tiny pellets that
are loaded into very long rods that are put into the power plant's reactor.
Inside the reactor of an atomic power plant, uranium atoms are split apart
in a controlled chain reaction.
In a chain reaction, particles released by the splitting of the atom go off
and strike other uranium atoms splitting those. Those particles given off
split still other atoms in a chain reaction. In nuclear power plants,
control rods are used to keep the splitting regulated so it doesn't go too
fast.
If the reaction is not controlled, you could have an atomic bomb. But in
atomic bombs, almost pure pieces of the element Uranium-235 or Plutonium,
of a precise mass and shape, must be brought together and held together,
with great force. These conditions are not present in a nuclear reactor.
The reaction also creates radioactive material. This material could hurt
people if released, so it is kept in a solid form. The very strong concrete
dome in the picture is designed to keep this material inside if an accident
happens.
This chain reaction gives off heat energy. This heat energy is used to boil
water in the core of the reactor. So, instead of burning a fuel, nuclear
power plants use the chain reaction of atoms splitting to |