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Nuclear reactors
Intermediate
Controlled chain reactions with moderators and control rods.
Fuel rods undergo controlled fission; a moderator slows neutrons, control rods absorb them, and coolant carries heat to turbines. About 33% efficient.
A 1 GW plant uses about 25 tonnes of fuel per year.
Needs safety systems.
In more detail
A nuclear reactor uses controlled fission to produce heat, which drives steam turbines to generate electricity. Control rods, moderators and coolants manage the reaction.
Real-world uses
- Nuclear power provides a large share of low-carbon electricity in some countries.
- Research reactors produce neutrons and isotopes for medicine.
- Nuclear reactors use moderators to slow neutrons and control rods to absorb them, so the reaction stays steady.
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Frequently asked questions
Why are moderators used?
They slow neutrons so that they are more likely to cause fission in uranium-235.
Do reactors produce waste?
Yes, spent fuel remains radioactive and must be managed for a long time.
What is a moderator?
A material such as water or graphite that slows neutrons so they are more likely to cause fission in uranium.
Related topics in Atomic & Nuclear Physics
Q-value · Nuclear fission · Chain reaction · Nuclear weapons · Nuclear fusion · Fusion in stars