Physics A-Level
Moderator
What Moderator means in Physics A-Level, as defined for AQA, OCR.
Definitions of Moderator
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Reference: AQA
Surrounds the fuel and slows fast fission neutrons to thermal energies through elastic collisions with light nuclei, increasing the probability of further fission.
A component that slows fast neutrons while minimising neutron absorption, and should contain light nuclei so elastic collisions remove neutron energy efficiently.
For example graphite or water, this slows fast neutrons to thermal energies because slow neutrons are more likely to induce fission in uranium-235.
Topics that use Moderator
- Induced fission (A-level only) (AQA A-Level)
- Nuclear fission and fusion (OCR A-Level)
Related terms
- Chain reactions
- Control rods
- Alpha and beta decay
- Balance of neutron production and absorption
- Barium
- Binding energy
- Binding energy per nucleon against nucleon number curve
- Characteristic X-rays from shell transitions
Using Moderator in the exam
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