Nuclear Energy Notes

Nuclear Energy

What is Nuclear Energy?

  • Nuclear energy is a form of energy released from the nucleus of atoms.
  • The nucleus is the core of atoms, made up of protons and neutrons.
  • This energy is released during nuclear fission or fusion.
  • It is often used to generate electricity.

Nuclear Fission

  • Nuclear fission is a process in which the nucleus of a heavy atom (like uranium-235 or plutonium-239) splits into two smaller nuclei.
  • This process also releases a few free neutrons and a large amount of energy.
  • How it works:
    • A neutron hits a heavy atomic nucleus.
    • The nucleus absorbs the neutron and becomes unstable.
    • It splits into two smaller nuclei.
    • This releases:
      • More neutrons
      • A lot of energy
      • Radiation

Nuclear Fusion

  • Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus.
  • This process releases a huge amount of energy.
  • How it works:
    • Two light nuclei (usually hydrogen isotopes, like deuterium and tritium) come very close together.
    • Under extremely high temperatures and pressure, they overcome their natural repulsion (since both are positively charged).
    • They fuse into a heavier nucleus (like helium), and in doing so:
      • Release a neutron
      • Release energy

Nuclear Reactor Components

  1. Fuel Rods
    • What it is: Cylindrical rods filled with fissile material (e.g., uranium-235, plutonium-239).
    • Purpose: Undergo nuclear fission, releasing heat energy.
  2. Moderator
    • What it is: A substance like graphite.
    • Purpose: Slows down fast neutrons, increasing the likelihood of fission.
  3. Control Rods
    • What it is: Rods made of materials that absorb neutrons (like boron or cadmium).
    • Purpose: Control the rate of fission by absorbing excess neutrons. Lowered to slow the reaction; raised to speed it up.
  4. Coolant
    • What it is: A fluid (CO₂).
    • Purpose: Carries heat away from the reactor core to a steam generator or turbine.
  5. Reactor Core
    • What it is: A strong container that houses the fuel, moderator, and control rods.
    • Purpose: Contains the nuclear reaction and withstands high pressure and temperature.
  6. Heat Exchanger / Steam Generator
    • What it is: A system where heat from the coolant turns water into steam.
    • Purpose: Transfers heat without mixing the coolant and the water used for turbines.
  7. Steam Turbine and Generator
    • What it is: A turbine connected to a generator.
    • Purpose: Converts thermal energy into electrical energy.
  8. Containment Building
    • What it is: A thick concrete and steel structure around the reactor core, often has a lead lining.
    • Purpose: Prevents radioactive leaks and protects the reactor from external hazards.

Pros & Cons of Nuclear Power

Pros:

  • Low Carbon Emissions.
  • Reliable Baseload Power.
  • Small Land Footprint.

Cons:

  • Radioactive Waste.
  • Risk of Accidents.
  • Uranium Mining and Processing.

Challenges

  • Toxic waste disposal, e.g. the gas circulated through the reactor core cannot be released in the atmosphere as it has become radioactive.
  • Risk of radiation/explosion.