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.