B4 - Fission and Fusion

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What does natural uranium consist of?
Two isotopes; uranium-235 and uranium-238
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When does fission occur?
When a large unstable nucleus is split up and energy is released as heat
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What happens in the process of fission?
The heat is used to boil water to produce steam, the pressure of the steam acting on the turbine blades make it turn, the rotating turbine turns the generator, producing electricity
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What happens when uranium fissions?
A chain reaction starts (an example is a nuclear bomb)
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What happens to atoms of uranium-235 in a nuclear power station?
Bombarded with neutrons which causes the nucleus to split which releases energy
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How is it a chain reaction?
Because further neutrons emitted cause further uranium nuclei to split.
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How can a graphite moderator control the output of a nuclear reactor?
It goes in between the fuel rods which slows down the fast moving neutrons emitted during fission. Slow moving neutrons are more likely to be captured by other uranium nuclei
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How can a boron control rod control the output of a nuclear reactor?
It can be raised or lowered. Boron absorbs neutrons, so fewer neutrons are available to split into more uranium nuclei. This controls the rate of fission.
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When does nuclear fusion happen?
When two light nuclei fuse (join) together releasing large amounts of heat energy
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What does fusion require?
Extremely high temperatures which have proved difficult to achieve and to manage safely on earth and so its use for power stations remains a dream
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Where does fusion take place in space?
In stars, where there are extremely high temperatures and pressures
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What are fusion bombs?
Started with a fission reaction which creates exceptionally high temperatures.
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What are scientists still trying to solve?
Solve the safety and practical challenges presented
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Why isn't cold fusion?
As realistic since any results are impossible to verify so far.
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Other cards in this set

Card 2

Front

When does fission occur?

Back

When a large unstable nucleus is split up and energy is released as heat

Card 3

Front

What happens in the process of fission?

Back

Preview of the front of card 3

Card 4

Front

What happens when uranium fissions?

Back

Preview of the front of card 4

Card 5

Front

What happens to atoms of uranium-235 in a nuclear power station?

Back

Preview of the front of card 5
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