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Radioactivity

Controlling a reactor and generating electricity

  • 2 things to know
  • Paper 1

Overview

The moderator and control rods and their materials, shutting a reactor down, how the coolant, boiler, turbine and generator turn fission energy into electricity, the sealed coolant loop, and handling and storing radioactive fuel rods and fission products.

What you need to know

Answer each one before you reveal it.

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Key term

Name a material used as the moderator in a nuclear reactor.

Key term

Why must neutrons be slowed down before they can cause fission in uranium-235?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is the job of the moderator in a nuclear reactor?

    Model answer

    It slows down the fast neutrons so that they are more likely to cause further fission.

  2. 2

    Name a material used as the moderator in a nuclear reactor.

    Model answer

    Graphite, or water.

  3. 3

    Why must neutrons be slowed down before they can cause fission in uranium-235?

    Model answer

    Fast neutrons are rarely absorbed by the nucleus, while slow neutrons are absorbed readily.

  4. 4

    What is the job of the control rods in a nuclear reactor?

    Model answer

    They absorb neutrons, so fewer are left to cause further fission.

  5. 5

    Name a material used for the control rods in a nuclear reactor.

    Model answer

    Boron, or cadmium.

  6. 6

    What happens to the rate of fission when the control rods are lowered further into a reactor core?

    Model answer

    More neutrons are absorbed, so the rate of fission falls.

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