Role of a moderator in nuclear power plants: identify the primary function. Context: A moderator is mixed with the fuel mass in thermal reactors. Choose the correct purpose it serves.
Mechanical Engineering
IC Engines and Nuclear Power Plants
Difficulty: Easy
Choose an option
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ASlow down the speed of fast moving neutrons
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BControl the reaction
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CReduce the temperature
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DExtract heat from nuclear reaction
Answer
Correct Answer: Slow down the speed of fast moving neutrons
Explanation
Given data
- Component: Moderator in a nuclear reactor
Concept/ApproachA moderator (e.g., light/heavy water, graphite) reduces the kinetic energy of fast neutrons via elastic scattering, increasing the probability of thermal fission in fuels like U-235.
Why other options are incorrect
- Control the reaction: That is primarily the job of control rods (absorbers), not the moderator.
- Reduce temperature / Extract heat: Heat removal is by the coolant circuit, not by the moderator per se (though some moderators are also coolants).
Final AnswerSlow down the speed of fast moving neutrons.