(455) Nuclear power plants [IB Physics SL/HL]

Nuclear Power Generation

• Purpose: Use nuclear power to generate electricity by turning a turbine.

  • Turbine: A wheel with magnets that, when turned, generates electricity through moving magnets.

  • Key Principles: Refer to Faraday's law and Lenz's law for those at higher levels.

Mechanism of Power Generation

• Basic Concept: Moving a magnet induces electricity.

  • Stillness of the magnet produces no electricity, while movement induces EMF (Electromotive Force).

  • Spinning turbines in wind power operate on the same principle.

Nuclear Fuel

• Uranium-235:

  • Enriched uranium-235 used in power plants; found naturally as uranium-238.

  • Fuel is manufactured into pellets and formed into fuel rods.

• Fission Process:

  • Neutrons fired at uranium-235 induce fission.

  • Fission creates uranium-236 and releases energy, neutrons, and byproducts.

Nuclear Reactor Components

• Moderator:

  • Slows neutrons down, increasing the likelihood of further reactions.

  • Common material: Graphite (carbon).

• Control Rods:

  • Can be raised or lowered to control neutron absorption and regulate the fission reaction.

  • Essential for maintaining temperature and preventing meltdowns.

Heat Generation and Energy Conversion

• Heat Exchanger:

  • Converts heat from the reactor to water, producing steam to turn turbines.

  • Highly efficient; one kilogram of uranium generates far more energy than coal.

Safety Measures

• Shielding:

  • Reactor structures incorporate thick steel and concrete to protect against radiation and overheating.

  • This prevents accidents and handles potential meltdown risks.

Nuclear Waste Management

• Waste Products:

  • Fission results in long-lived radioactive waste requiring careful handling and disposal.

  • Types include uranium-236 and plutonium-239.

  • Common disposal methods: sealed thick containers of steel and lead, sometimes buried underground.

• Regulatory Considerations:

  • Accidents, like Chernobyl, emphasize the importance of safe waste management and reactor maintenance.

Future of Nuclear Energy

• Nuclear Fusion:

  • Potentially a cleaner alternative, fusing hydrogen into helium with valuable byproducts.

  • Current challenges: high energy input required and difficulty in controlling reactions.