Correct option is D
The correct answer is (d) All of these
In nuclear reactors, a moderator is a material used to slow down fast neutrons to thermal neutrons, making them more likely to cause fission in the nuclear fuel (e.g., uranium-235 or plutonium-239).
The following materials are commonly used as moderators:
Graphite:
- Graphite is a solid form of carbon that is an effective moderator due to its ability to slow down neutrons without capturing them.
- It has been used in reactors like the RBMK and Magnox designs.
Paraffin:
- Paraffin, a hydrocarbon wax, was historically used in early experimental reactors.
- It is effective at slowing down neutrons because of its hydrogen content.
Heavy Water (D₂O):
- Heavy water, made of deuterium (a heavier isotope of hydrogen) and oxygen, is an excellent neutron moderator because it slows down neutrons effectively while absorbing very few.
- Used in reactors like the CANDU reactors (Canada Deuterium Uranium).
Additional Information:
- A nuclear reactor is a device used to initiate and control a sustained nuclear chain reaction for energy production, research, or other applications.
- It operates by harnessing energy released during nuclear fission, where heavy atomic nuclei (e.g., uranium-235 or plutonium-239) split into smaller nuclei, releasing heat.
Key Components:
- Fuel: Contains fissile material (e.g., uranium-235 or plutonium-239).
- Moderator: Slows down neutrons (e.g., graphite, heavy water).
- Coolant: Removes heat generated (e.g., water, liquid sodium).
- Control Rods: Regulate the fission reaction by absorbing neutrons.
- Containment Structure: Ensures safety by preventing radiation leaks.
Types:
- Pressurized Water Reactor (PWR): Uses light water as coolant and moderator.
- Boiling Water Reactor (BWR): Produces steam directly in the reactor.
- Heavy Water Reactor (e.g., CANDU): Uses heavy water as a moderator.
- Fast Breeder Reactor (FBR): Produces more fissile material than it consumes.
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