Control of Reaction Rate

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Control of Reaction Rate

• Michael Bragg and Dominic Dunn

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Moderators

• The neutrons have kinetic energies of several
  MeV.
• The job of the moderator.
• In general, the better a material is at
  "moderating" the neutrons, the less the fuel
  needs to be enriched.
• Sometimes the same material is used as a coolant.
  

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• Common moderators include
• Water
• Heavy water D20 (deuterium oxide)
• Graphite

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Control rods

• What are control rods?
• What are they made from?
• Materials used include
• How are they used?
• The most important function

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Coolant

• The job of the coolant?
• keeping the reactor cool enough to prevent a
  meltdown.
• Moderating function

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Desirable properties for a coolant include

• Low absorption cross section
• Abundant and Inexpensive
• Noncorrosive or low corrosivity
• High heat transfer coefficient.
• Low viscosity
• Can be kept as a liquid to high temperatures,
  even if it is under pressure.