Video Transcript
What is the name of the rods used
to absorb neutrons and slow down the reaction in a nuclear reactor? (A) Graphite rods, (B) control
rods, (C) meltdown rods, (D) fuel rods, or (E) reaction rods.
Nuclear reactors use fission chain
reactions. They split atoms of uranium-235
repeatedly, releasing neutrons and energy. The neutrons that are produced go
on to split more uranium atoms. Each fission of uranium-235
requires just one neutron and one atom of uranium-235 but produces between two and
three neutrons and a lot of energy.
This means that if neutrons are not
controlled, the reaction will multiply exponentially. The first fission will produce
three neutrons, which then produce three fissions, leading to nine neutrons, which
then produce nine fissions and 27 neutrons, and so on.
For a chain reaction to
exponentially grow like this is very dangerous since each fission releases a huge
amount of energy. So the reaction needs to be
controlled. Control rods are inserted into the
nuclear reactor to regulate the number of neutrons and slow down the reaction. Control rods contain materials like
cadmium, which is very good for absorbing neutrons. When neutrons hit the control rod,
they are absorbed and don’t multiply. So the reaction doesn’t get out of
control.
So the name of the rods used to
absorb neutrons and slow down the reaction in a nuclear reactor is (B) control
rods.
