Without a doubt finding sustainable, everlasting energy sources has been a dream for humankind. The 1950s were the golden age in nuclear technology development, starting from Experimental Breeder Reactor I (EBR-I) at Idaho National Laboratory, and six years later shippingport Pressurised Water Reactor (PWR) capable of producing 60 MWe. As of today, the fission reactors are coming in diverse classes, PWR, Boiling Water Reactor (BWR), Pressurised Heavy water Reactors (PHWR), Light Eater Reactors (LWR), all with different key factors influencing their deployment, cost, safety, and non-proliferation attributes, and fuel cycle management.
The most recent developments which expect deployment in the next two decades are known as Gen IV with two categories of thermal and fast reactors, aiming to reduce the waste by breeding more fuels than they consume. They potentially offer a significant advantage over the past generations in terms of safety, sustainability, cost, and proliferation resistance. The fission reactors work by splitting a uranium atom into smaller fractions known as fission and releasing total binding energy of 8.8 x 1013 J/kg. U-235 includes 92 protons and 143 neutrons, with a somewhat unstable nucleus. Once the U-235 absorbs an extra neutron it quickly disintegrates and releases two or more neurons creating a chain reaction.
While fission reactors are established on atomic disintegration, there is another process that works in an opposite way, known as Fusion. In the fusion process, the light atoms such as hydrogen (deuterium H-2 and tritium H-3) are heated up and pressurised together to form a heavier nucleus (Helium). The process in return releases 3.4 x 1014 J/kg and that is 3.86 times more than the energy released in the fission process. The physics behind this is the fact that the binding energy per nucleon is a function of its mass number and keeps increasing to a maximum atomic number of 56 which is iron (Fe-56), and beyond Fe-56, the binding energy per nucleon decreases.
While the core temperature of the Sun reaches 15 million degrees Celsius, the gravitational force confines the positively charged hydrogen and cause the nuclei to collide at high speed and overcome the repulsion force known as the Coulomb force between the positive charges and consequently fusing them. The process of energy production is concentrated in the centre of the stars under extreme pressure of 1016 Pa (in the Sun). It is estimated 1038 fusion reactors to occur per second, releasing 1026 W.
But fusion on Earth is a similar but different story. Our devices do not have the privilege of the Sun’s gravity, therefore scientists have to overcome the challenge with other means. That means higher temperatures and finding ways to keep the pressure on.
The first fusion experiment started in the 1930s and by the mid-50s, fusion devices were operating in the Soviet Union, the UK, US, France, Germany and Japan. The first major breakthrough happened in 1968 when the Soviet researchers claimed to achieve 10 million degrees Celsius and managed to confine the plasma for an order of milliseconds. the doughnut-shaped machine was called tokamak. To verify the Russian’s claim a team of five from Culham was dispatched at the height of the cold-war era to meet Lev Artsimovitch, the head of Kurchatov Institute to verify the result. At the time, the UK was operating the Zero Energy Thermonuclear Assembly (Zeta) based on the pinch plasma confinement reaching 5 million degrees Celsius.
As of today, there are several methods of reaching fusion on Earth, Magnetic Confinement Fusion (MCF), Inertial Confinement Fusion (ICF), Pinches, Electrostatic Confinement and a recent hybrid scheme known as Magnetised Target Fusion (MTF). United Kingdome alone is home to a few major fusion research developments at Oxfordshire. First Light Fusion Ltd, Culham Centre for Fusion Energy, operating JET(the Joint European Torus), and Mega Ampere Spherical Tokamak (MAST), Tokamak Energy Ltd, operating Spherical Tokamak (ST40) and soon to house General Fusion’s MTF.
The source of fusion fuel is unlimited and is the most abundant element in the universe. For every 5,000 hydrogen atoms in seawater, there is 1 atom of deuterium and when fusion becomes a reality for every 4 litres of seawater we can produce as much energy as ~1000 litre of gasoline. Tritium on the other hand is rare, however, can be produced by breeding the element of lithium which can be found plenty at the Earth’s crust. Hence, access to inexpensive, and reliable clean energy is vital for accomplishing our sustainable goals, which eventually eliminates poverty and increases living standards. The low carbon electricity produced for example by fusion can be widely available with its source being reachable in every corner of the planet to bring light to the lives of the poorest and those in need. There are no harmful toxins and other greenhouse gases. Fusion energy is the reason to be excited about the future.
To be continued.