Nuclear Fusion Reactors

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The  process in which the nuclei of two light atoms combine to form a new nucleus is known as nuclear fusion. It is the process that powers the sun and the stars, and is the ultimate energy source for the future of mankind as it is another way of producing nuclear energy like nuclear fission.

The combination of Deuterium and Tritium, the two isotopes of Hydrogen to give Helium and releasing a neutron and giving out around 17 MeV of energy is an example of a nuclear fusion.

Nuclear Fusion reactions occur when two or more nuclei of the atom come close enough up to the extent that the nuclear force pulling them together exceeds the electrostatic force that pushes them apart, fusing them into heavier nuclei. For nuclei lighter than iron-56 the reaction is exothermic in nature thus releasing energy while for nuclei heavier than iron-56, the reaction is endothermic in nature thus requiring energy. 

Therefore we can say that nuclei smaller than iron-56 are more likely to fuse while those heavier than iron-56 are more likely to break apart.

Nuclear Binding Energy and Nuclear Fusion

When two lighter nuclei undergo fusion reaction, the combination has a mass that is less than the mass of the initial individual nuclei. This difference in the mass between the reactants and products is compensated by either the release or absorption of energy known as binding energy between the atomic nuclei before and after the reaction. 

Einstein’s mass-energy equivalence explains the energy that the reaction gives out energy during Fusion.

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Types of Fusion Reactors 

There are several approaches to control and contain a fusion reaction to exist, but the two primary approaches based on confinement are on the concept of magnetic confinement, and inertial confinement.

Magnetic confinement fusion (MCF) reactors are the more advanced of the two approaches, as and in this they utilize magnetic fields generated by electromagnetic coils to confine a fusion plasma in a donut-shaped (torus) vessel.

 Unlike magnetic confinement approaches, inertial confinement fusion (ICF) approaches attempt to externally heat and compress fusion fuel targets to achieve the very high temperatures even higher densities required to initiate the nuclear fusion. 

For most ICF concepts and approaches, high power lasers are used to compress and heat the fuel.

Recently, a third approach, which exploits the parameter space between the conditions produced and needed for magnetic and inertial confinement has gained traction in recent years, and is receiving much scientific, and even commercial, attention. This is called Magnetized target fusion (MTF), sometimes known as magnetized inertial fusion (MIF), it looks to exploit the use of higher density plasmas than for MCF approaches, but lower power lasers and other drivers than those used in ICF approaches. MTF offers a unique route to fusion, and the accelerated development of a number of unique concepts has seen significant support.

Components of Magnetic Confinement Reactors

  1. Vacuum vessels are used to hold the plasma and to keep the reaction chamber in a vacuum.

  1. Neutral beam injector is used to inject particle beams from the accelerator into the plasma thus heating the plasma to its critical temperature.

  1. Magnetic field coils are used in magnetic fields, and the plasma is confined in the superconducting magnets.

  1. Central solenoid is used to provide electricity to the magnetic field coils.

  1. Cooling equipment is  used to cool down the magnets.

  1. Blanket modules: These are generally used to absorb heat and high-energy neutrons from the fusion reaction.

  1. Diverters: They are used to exhaust the helium products.

Advantages of Nuclear Fusion

Fusion is capable of powering the whole world at very low cost, since there is virtually limitless fuel available that can be used to make electricity.There is a lot of energy released in fusion rather than fission, therefore it would be more profitable if it is set up. Also when producing nuclear fusion energy, there is hardly any waste. As a result of this, there would be no money wasted in disposing and clearing of the wastes produced by reaction. Thus, Fusion is capable of powering the entire world at a much low cost, as compared to power sources used nowadays. It is a clean energy source that means no greenhouse gases and emitting only helium as exhaust .It is easier to stop nuclear fusion reaction as compared to fission reaction since there is no chain reaction in fusion.

Disadvantages of Nuclear Fusion

It would be really very expensive to build a power plant to produce energy because Nuclear fusion  can only occur between 14999726.85 degree celsius to 9999726.85 degree Celsius. (Or 10-15 million kelvin) Thus, there are no materials that can cope with 10-15 million K and also since it is a non-renewable energy. There can also be radioactive wastes.

FAQ (Frequently Asked Questions)

Q1. List Some Effects of Fusion on the Environment?

Fusion is one of the most environmentally friendly sources of energy and also there is  no CO2 or other harmful atmospheric emissions during the process of the fusion, this means that fusion does not contribute to greenhouse gas emissions or global warming. The two sources of fuel of fusion, hydrogen and lithium, are widely available in many parts of the Earth.

Q2.What is the Point of difference and Similarity between Nuclear Fission and Nuclear Fusion?

Both nuclear fusion and fission are nuclear processes as they both involve nuclear forces to change the nucleus of atoms. The fission nucleus of heavy element splits (with a high atomic mass number) into fragments; while fusion nucleus of two lighter elements joins  (with a low atomic mass number), forming a heavier element. 

In both cases, energy is freed because the mass of the remaining nucleus is smaller than the mass of the reacting nuclei and why the opposite processes release energy can be understood by examining the binding energy per nucleon curve.

Q3.Does the Fusion Process Produce Radioactive Nuclear Waste the Same Way Fission does?

Nuclear fission power plants have the disadvantage of generating unstable nuclei; some of these are radioactive for millions of years while fusion on the other hand does not create any long-lived radioactive nuclear waste. 

A fusion reactor mainly produces helium, which is an inert gas. It also produces tritium which is consumed within the plant in a closed circuit.