84. Nuclear Fission

Nuclear fusion is the process where two light nuclei join (fuse) together to form a single, heavier nucleus. This process releases massive amounts of energy and is the reaction that powers stars like the Sun.

1. How Fusion Works

  • The Process: Two light nuclei (such as isotopes of hydrogen) collide at very high speeds and fuse into a larger nucleus (such as helium).

  • Mass-Energy Conversion: The reason fusion releases so much energy is that the mass of the resulting single nucleus is slightly less than the total mass of the two original nuclei. This "lost" mass is converted directly into energy.

  • Einstein's Equation: Although you don't need to calculate it for GCSE, this conversion follows E = mc² Because the speed of light (c) is so high, even a tiny amount of mass creates a huge amount of energy.

2. Fusion vs. Fission

It is crucial not to confuse these two nuclear processes:

Feature

Nuclear Fusion

Nuclear Fission

Action

Joining two light nuclei

Splitting one large nucleus

Energy Released

Extremely High (more than fission)

High

Requirements

Very high temperature and pressure

Neutrons to trigger the split

Current Use

Stars (not yet viable on Earth)

Nuclear power plants on Earth

3. Pros and Cons of Fusion

If scientists can eventually make fusion work on Earth, it would have significant advantages over current nuclear power:

  • Pros:

    • No Radioactive Waste: Unlike fission, fusion does not produce long-lived radioactive waste.

    • Abundant Fuel: The hydrogen needed for fuel is easily sourced (e.g., from water).

    • Clean: It does not produce greenhouse gases.

  • Cons:

    • Extreme Conditions: Fusion only happens at temperatures around 10 million degrees Celsius and very high pressures.

    • Technical Difficulty: We currently cannot build a reactor that can contain these conditions and produce more energy than it consumes.