Tip:
Highlight text to annotate it
X
A nuclear reactor works by splitting up large atoms such as uranium. This is known as nuclear
fission. These large atoms are very unstable and can be split up by firing a neutron at
them. They split into smaller atoms and a number of neutrons. If we measure the mass
of the initial atom and the total mass of the products after the split, there it seems
to be a discrepancy. Some mass seems to be lost. Einstein's famous equation, E=MC^2,
shows that this incredibly small amount of lost mass is converted into a huge amount
of heat energy. So we know that each atom splitting up gives off some heat energy. But
it gets really exciting when you put a bunch these atoms together. As one atom splits up,
it releases some energetic neutrons, ready to split up some more atoms which in turn
releases more energetic neutrons, which will split up some more atoms, and on and on. This
is known as a chain reaction. The problem is, if we don't control this reaction we
soon end up with an incredible amount of heat energy, which is impossible to control, resulting
in what is known as a nuclear meltdown. Which isn't very useful when trying to run a power
station.
To control the rate of reaction we need a substance, which can absorb the neutrons,
stopping them from splitting up other atoms. In a nuclear reactor, this is done by control
rods. When lowered, these control rods stop the reaction if necessary. They are built
and positioned in a way that ensures they drop into the fuel in the case of an emergency
such as a power cut. During normal operation they are raised and lowered accordingly to
vary power output. The lower they are, the lower the rate of reaction, which means a
smaller output. The higher they are, the higher the rate of reaction, which means a greater
power output. With the aid of the control rods and other design features, nuclear reactions
can be regulated meaning there is a constant production of manageable heat energy, which
then can be used to heat water into pressurised steam. This is then used to turn turbines
connected to a generator, producing large amounts of electrical energy. Nuclear reactions
can release a lot of energy which can be very dangerous, but because of the ever-growing
hunger for energy scientists are working very, very hard to make this technology safer, and
potentially reducing the use of fossil fuels.