The word ‘nuclear’ strikes fear amongst many, with disasters such as Chernobyl, disfigured children and terrifying nuclear bombs at the forefront of everyone’s mind. However, this perception needs to be adapted, as nuclear fusion could now be the answer to renewable energy.

Nuclear fusion reaction research is on the rise, and for the past 50 years, scientists have created and explored ideas to generate colossal amounts of low-carbon renewable energy. A minor detail perhaps? Nuclear fusion reactions are the force powering the Sun.

In a nuclear deuterium- tritium (DT) fusion reaction, incredibly high amounts of kinetic energy are produced, and the temperature reaches in excess of 100 million degrees Kelvin. If the reaction was to malfunction, the plasma would melt its way through the earth without much bother at all.

Currently, the most developed apparatus to reach the temperatures and densities suitable for initiating reactions is the Tokamak, invented in the 1950s by Soviet physicists Igor Yevgenyevich Tamm and Andrei Sakharov. The nuclear reactions take place inside a doughnut-shaped containment vessel. Because particles within are charged, plasma is held in place by powerful magnetic forces to prevent it from immediately liquefying the vessel walls. As the reaction proceeds, the kinetic energy increases, and is transferred to the surrounding liquid metal, which reduces the temperature to a safer 600-700?K. The liquid metal transfers the energy to water which converts to steam to power the turbines generating the electricity.

The starting materials are abundant on earth, and an enormous amount of energy can be produced from them. 10g of deuterium (extracted from 500 litres of water) and 15g of tritium (from 30g of lithium) produces enough electricity for the average person’s lifetime.

The downside? If this was indeed a viable option, it would not be complete before 2050.

Marie Chapman

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4 Comments

  1. Dan
    April 30, 2010 at 18:41 — Reply

    you said <>

    actually Fusion cannot runaway, at worst it would break the machine that creates fusion. once the plasma escapes there would be local heating, and the reaction stops. There’s really not that much plasma in these reactors, a couple cubic yards at most.

    It’s much safer than fission (that can have runaway reactions).

  2. Dan
    April 30, 2010 at 18:42 — Reply

    sorry it cut out my quote you said:
    If the reaction was to malfunction, the plasma would melt its way through the earth without much bother at all.

  3. Philip Whitehead
    May 1, 2010 at 10:58 — Reply

    Dan is correct. The picture at the top of the page is the JET (Joint European Torus) reactor, currently the largest fusion reactor in the world, near Culham in Oxfordshire (http://www.fusion.org.uk). The volume of the plasma inside JET is a few hundred cubic metres, but it is at such a low density that it has a mass of only a few grams. Were the magnetic fields to fail completely, the heat would dissipate so quickly it would not “immediately liquify the [stainless-steel vacuum] vessel walls”. Fusion reactors are inherently safe, as far as the nuclear reaction is concerned, as Dan points out. The biggest risk factor is actually posed by the normal risks associated with large electromagnets, common to their application in any heavy industrial setting.

    A commerically-viable fusion reactor would be bigger, but no more dangerous. I’d much rather live next to a fusion power plant than a conventional (fission) nuclear power plant, or a fossil-fuel plant. In fact, you can see the massive coal- and gas- fired Didcot Power Station from Culham, and hope that one day it won’t be there any more, replaced by a smaller, safer and much greener Fusion plant.

  4. Marie's Mum
    May 3, 2010 at 14:44 — Reply

    so proud of you… my girl. All grown up 🙂 x x x

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