Nuclear Fission

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What is nuclear fission?
Nuclear fission is a type of nuclear reaction that is used to release energy from uranium or plutonium atoms.
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Describe what happens in a fission chain reaction.
A slow neutron is fired at an isotope of uranium-235. The neutron is absorbed by the nucleus which makes the atom unstable and causes it so split. By this, it forms two lighter elements and thermal energy is released.
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How does the chain reaction carry on once two daughter nuclei have been produced?
Each time a uranium atom splits, two or three neutrons are spat out which can hit other uranium nuclei causing them to split too.. = chain reaction.
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What happens in a nuclear power station?
They are powered by nuclear reactors. In a reactor, a controlled chain reaction takes place in which uranium atoms split up. The heat energy released by fission is used to boil water to drive a steam turbine, which turns a generator = electricity.
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How are chain reactions controlled in reactors?
Uranium fuel rods are placed in a moderator (e.g. water), to slow down the fast moving neutrons. This creates a steady rate of fission, where one neutron produces another fission.
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What are control rods?
Control rods, often made of boron, limit the rate of fission by absorbing excess neutrons. They are placed in between the fuel rods and are raised and lowered into the reactor. This also helps to control the reaction.
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Other cards in this set

Card 2

Front

Describe what happens in a fission chain reaction.

Back

A slow neutron is fired at an isotope of uranium-235. The neutron is absorbed by the nucleus which makes the atom unstable and causes it so split. By this, it forms two lighter elements and thermal energy is released.

Card 3

Front

How does the chain reaction carry on once two daughter nuclei have been produced?

Back

Preview of the front of card 3

Card 4

Front

What happens in a nuclear power station?

Back

Preview of the front of card 4

Card 5

Front

How are chain reactions controlled in reactors?

Back

Preview of the front of card 5
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