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Radioactivity
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Generating Electricity using Nuclear Power.
What is Fission?
Nuclear power stations get their energy from a
type of nuclear reaction called
fission.
Fission means splitting a big
nucleus into smaller nuclei.
Fission is not the
same process as fusion.
There are advantages
and disadvantages in
using nuclear power to generate
electricity.
Why is Energy Released
when a Nucleus is Split?
A large
amount of energy is
released when the nucleus is split,
much larger than the amount of energy in a
chemical bond.
If you add up the mass of the nuclei before and after fission,
you find that some mass has gone missing.
The process of fission (and fusion)
destroys a
little bit of mass.
This little bit of mass turns into a large
amount of energy.
The amount of energy can be calculated using Einstein's
equation
E = mc2
where E is energy, m
is mass and c is the speed
of light.
The energy released
from fission is used to
generate electricity.
What is the Fuel for Nuclear
Power Stations?
Nuclear power stations use
either uranium-235 or plutonium-239.
Most
nuclear power stations use uranium as their
fuel
but the process of fission described below is the same
for both.
Uranium-235 can capture a neutron and become uranium-236.
Uranium-236 is unstable and splits to form 2 smaller
nuclei
(called daughter nuclei)
plus an additional 2 or 3 neutrons.
These additional neutrons can be captured
by
other atoms
of uranium-235 and
so the process continues.
What is a Chain Reaction?
The type of process where one
atom splits to release neutrons
which then cause other atoms to
split which release more
neutrons
which cause other atoms to
split and so on is called
a
chain reaction.
A moderator
and control
rods in the
reactor core
are used to control the speed
of the chain reaction.
The smaller
nuclei produced by fission are
themselves
radioactive and these radioactive smaller
nuclei
contribute
to an ever increasing
amount of radioactive
waste.
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Radioactivity
Revision Questions
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