What is the main purpose of a moderator in a thermal nuclear reactor?
A to shield the surroundings from ionising radiations
B to decrease the number of fission chain reactions
C to decrease neutron speeds
D to prevent the core from overheating - AQA - A-Level Physics - Question 29 - 2021 - Paper 2
Question 29
What is the main purpose of a moderator in a thermal nuclear reactor?
A to shield the surroundings from ionising radiations
B to decrease the number of fission cha... show full transcript
Worked Solution & Example Answer:What is the main purpose of a moderator in a thermal nuclear reactor?
A to shield the surroundings from ionising radiations
B to decrease the number of fission chain reactions
C to decrease neutron speeds
D to prevent the core from overheating - AQA - A-Level Physics - Question 29 - 2021 - Paper 2
Step 1
A to shield the surroundings from ionising radiations
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Answer
Incorrect. This is not the primary function of a moderator in a thermal nuclear reactor.
Step 2
B to decrease the number of fission chain reactions
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Answer
Incorrect. While moderators control the reaction, their main role is not to decrease the number of fission reactions.
Step 3
C to decrease neutron speeds
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Answer
Correct. The main purpose of a moderator is to slow down fast neutrons produced during fission, making them more likely to induce further fission in fuel nuclei.
Step 4
D to prevent the core from overheating
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Answer
Incorrect. While cooling is important for safety, it is not the primary function of a moderator.
