Nuclear Radiation: Nuclear Fusion

Nuclear Radiation: Nuclear Fusion

Nuclear Fusion: Overview

  • Nuclear fusion is a process where two light nuclei combine to form a heavier nucleus.
  • It’s the energy producing process that takes place at the core of the sun and other stars.
  • Unlike nuclear fission, nuclear fusion releases energy by combining nuclei, and doesn’t produce long-lived radioactive waste.

Conditions for Nuclear Fusion

  • Temperatures must be incredibly high, typically tens of millions of degrees, for nuclei to come together.
  • Density needs to be high because nuclei need to be close together to fuse.
  • There must be very high pressure, to overcome the electrostatic repulsion between the positively charged nuclei.

The Process of Nuclear Fusion

  • In the sun, the most prominent fusion process involves hydrogen nuclei (protons) combining to form helium.
  • This is referred to as the proton-proton chain and occurs in three steps:
    • Two protons fuse to form a deuteron, a positron and a neutrino.
    • The deuteron then fuses with another proton to form helium-3 and a photon.
    • Finally, two helium-3 nuclei fuse to form helium-4 and two protons.

Fusion Power Generation

  • Efforts are being made to reproduce nuclear fusion on earth as a source of power, with concepts like the tokamak.
  • A significant challenge is achieving and maintaining the necessary temperature and pressure conditions.
  • Currently, fusion power plants are not commercially viable because they use more energy to maintain the conditions than the energy they produce.

Advantages of Nuclear Fusion

  • Fusion has the potential to provide a nearly inexhaustible source of energy, as hydrogen is abundant in sea water.
  • Fusion reactions produce less radioactive waste than nuclear fission, and the waste they do produce has a shorter half-life.
  • Fusion doesn’t produce greenhouse gases, and there’s less risk of a catastrophic accident compared to nuclear fission.

Difficulties and Challenges

  • The main issues with nuclear fusion include the high costs, the complex technology needed, and the difficulties in containing the high temperature plasma.
  • Currently, more energy is required to initiate and maintain a fusion reaction than is produced, which makes fusion energy not yet viable.
  • There are containment issues, as plasma must be kept away from the reactor walls to avoid damage and energy losses.