Despite the dangers of nuclear power, it supplies almost 20% of the world's electricity. So what's being done to make this great energy source safer? Read on to find out!

Nuclear Fusion Reactors

In light of the Japan disaster and rising gasoline prices, nuclear fusion reactors seem to be the answer to all our energy concerns. Unlike fission reactors, fusion reactors would use fuels commonly found in seawater, produce much less radioactive waste, and emit much less radiation. Sounds like a dream come true, right? The problem is, fusion reactions can only occur under certain conditions; extreme heat and extreme pressure. In fact, nuclear fusion needs requires such high amounts of heat and pressure that it only occurs in stars and hydrogen bombs. Fortunately, scientists believe that they can create the conditions necessary to make nuclear fusion a reality.

Fusion vs Fission

Fission reactions are the reactions that power all nuclear reactions today. Typically, this involves the splitting of an atom, thereby releasing energy. In most reactors today, the atom splitting is uranium 235, which undergoes decay naturally. However, because this reaction also gives off dangerous radiation, and produces much greater amounts of radioactive waste than fusion reactions. For more information on modern reactors see our page on The Workings of a Nuclear Power Plant

Fusion, on the other hand, is the release of energy that results from the combination of two atoms. Plans for future fusion reactions use the combination of deuterium and tritium to create helium and neutrons. This reaction is what powers the sun and releases a great deal of energy with much less radioactive waste being produced. The images below show what a fusion reaction looks like.
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Conditions Needed For Nuclear Fusion
As I said earlier, fusion reactions require extreme heat and pressure in order to happen. In fact, fusion reactions require temperatures in excess of 100 million Kelvin, approximately 6x hotter than the sun! Atoms must also be within 1x10 (-15). This is very difficult to do, since protons are repulsed by each other. Scientists believe that they have found ways to replicate these conditions closely enough to make nuclear fusion a reality.

The ITER Power Plant

The United States, Russia, Europe and Japan planned the building of International Thermonuclear Experimental Reactor (ITER) in Cadarache, France, to create the world's first functional nuclear fusion reactor. France, which already receives 70% of its electricity from nuclear power, and therefore is the perfect proving ground for this revolutionary power source.


To create proper conditions for nuclear fusion, scientists believe they can use magnetic confinement. This process involves using magnetic and electric fields to heat and squeeze hydrogen until it becomes plasma. Concept-wise, the process is actually very similar to the mass spectrometry.First, hydrogen gas is heated by microwaves, electricity and neutral particle beams from accelerators. This turns the gas into plasma. This plasma gets squeezed by super-conducting magnets, thereby allowing fusion to occur. The most efficient shape for the magnetically confined plasma is a donut shape


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ITER tokamak reactor

First of all, tokamak is a Russian acronym for; toroidal chamber with axial magnetic field

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Vacuum vessel - holds the plasma and keeps the reaction chamber in a vacuum
Neutral beam injector (ion cyclotron system) - injects particle beams from the accelerator into the plasma to help heat the plasma to critical temperature
Magnetic field coils (poloidal, toroidal) - super-conducting magnets that confine, shape and contain the plasma using magnetic fields
Transformers/Central solenoid - supply electricity to the magnetic field coils
Cooling equipment (crostat, cryopump) - cool the magnets
Blanket modules - made of lithium; absorb heat and high-energy neutrons from the fusion reaction
Divertors - exhaust the helium products of the fusion reaction

Another approach to creating these conditions is inertial confinement
This process involves using lasers or ion beams to squeeze and heat the hydrogen gas. It is currently being investigated at the National Ignition Facility of the Lawrence Livermore Laboratory.
This approach was successfully used to fuse two deuterium nuclei in 2010.



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Bibliography (4)

  1. Freudenrich, Ph.D., Craig. “HowStuffWorks ‘How Nuclear Fusion Reactors Work’” Howstuffworks 11 August 2005. Web. 26 April 2011.
  2. Cross, Alasdair. "BBC News - Is Fusion Power Really Viable?" BBC News - Home. Web. 26 Apr. 2011. <http://news.bbc.co.uk/2/hi/8547273.stm>.