Nuclear reactions as a source of energy
2 marks · NormalName and briefly describe the function of two components used to control the rate of fission reactions in a nuclear reactor.
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Control rods and moderator: Control rods absorb excess neutrons; the moderator slows down neutrons.
Also accept: Moderator slows neutrons so they can cause fission more effectively. Control rods absorb neutrons to control the chain reaction.
Common mistakes: Mixing up control rods and moderator roles
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Marking points
B1 · 1 mark · Names control rods and correctly describes their function (absorb neutrons).
B1 · 1 mark · Names moderator and correctly describes its function (slows down neutrons).
Worked solution
Control rods: these absorb excess neutrons to control the chain reaction. Moderator: this slows down fast neutrons, making them more likely to cause further fission.