THERMONUCLEAR FUSION: DECODING CONCEPTS                

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Context

• Recently, the Joint European Torus (JET) fusion experiment in Oxfordshire, U.K., produced 59 megajoules (MJ) of energy from thermonuclear fusion.

 

Thermonuclear fusion

• Thermonuclear fusion is the process by which hydrogen atoms combine to produce helium inside the Sun, and release immense energy in light and radiation.
• Ordinarily, these atoms cannot fuse. But in the sizzling heat at the core of the Sun with the intense pressure and dense core, the plasma of hydrogen fuse with each other to form helium, spewing colossal energy in the form of light and heat.

Why is fusion a better option than fission to generate power?

• Nuclear fusion requires less fuel than fission.
• Fusion is carried out by using deuterium (an isotope of hydrogen) as fuel, which is quite abundant in nature. In contrast, the fuel necessary for fission (uranium, plutonium or thorium) is very hard to get – and highly expensive.
• Unlike fission, nuclear fusion does not produce any radioactive waste; it only produces helium atoms as a byproduct, which we can actually use to our benefit in various ways.
• Since fusion doesn’t produce runaway chain reactions the way fission can, there’s practically no risk of a meltdown in the case of nuclear fusion.
• A kilogram of fusion fuel contains about 10 million times as much energy as a kilogram of coal, oil or gas.

 

Why couldn’t we use Nuclear Fusion then?

• For fusion to occur on Earth, we need a temperature of at least 100 million degrees Celsius—six times hotter than the core of the sun. The sun is a natural fusion reactor which makes up for its measly 15 million degrees with the intense pressure created by its core's gravity.
• Experimental fusion reactors do exist –– but they consume way more power than they produce, which basically defeats the purpose of generating power using fusion.
• It’s also quite difficult to find materials that can withstand the reaction.
• It requires a lot of excess energy in order to keep the fusion reaction going once it has started.
• If fusion has to occur, the first step has to be the creation of hot plasma. Heating a tiny pellet of hydrogen to millions of degrees and generating plasma is not that hard. However, to keep the fiery plasma at millions of degrees from touching the container wall is a challenge.

 

Developments in the recent years

• Today, we conduct fusion reactions in a machine/reactor called the Tokamak.
• Harnessing energy from thermonuclear fusion today is a global collaborative effort.
• Thirty-five countries, including India, Russia, the United States, the United Kingdom, China, European Union, are collaborating to jointly build the largest Tokamak as part of the International Thermonuclear Experimental Reactor (ITER).

 

Tokamak ·        The Tokamak is an acronym for a Russian term which means "toroidal chamber with magnetic coils". ·        Tokamaks were first conceptualised by Soviet physicists Igor Tamm and Andrei Sakharov. ·        They theorised that if one can create a magnetic field in the shape of a torus then the scorching plasma could be contained. ·        The scalding of the walls of the container from the intense heat of plasma could be prevented. ·        Unlike fission reactors, fusion reactors like the tokamaks do not pose the dangers of a radioactive leak. ·        Gram for gram, the thermonuclear power produces four million times more energy than burning coal. The only waste product is harmless helium.

 

ITER About ITER is an international nuclear fusion research and engineering megaproject aimed at replicating the fusion processes of the Sun to create energy on the Earth. ITER is funded and run by seven member parties: China, the European Union, India, Japan, Russia, South Korea and the United States. Genesis The idea germinated in 1985. After years of ups and downs since March 2020, the machine assembly is underway at France. With the installation of the Cryostat, a device to cool the reactor, covering the assembly is slated to be completed by 2025. Method The ITER fusion reaction will use the isotopes of hydrogen called deuterium and tritium. To create plasma for fusion, the mixture of deuterium and tritium needs to be heated to temperatures 10 times hotter than the Sun's centre. Using strong magnets, the weltering plasma must be held in place, made to swill around, beams collide, fuse and release tremendous energy as heat. The heat must be removed from the reaction to boil water, produce steam and turn a turbine to generate electricity. Significance If all goes well, the first plasma will be produced at the end of 2025. After testing and troubleshooting, energy production will commence in 2035.The plant is expected to generate 500 MW power and consume 50 MW for its operation, resulting in a net 450 MW power generation.

 

• Recently, China’s “artificial sun” set a new record after it ran at 120 million degrees Celsius for 101 seconds, according to the state media.
• The Experimental Advanced Superconducting Tokamak (EAST) device designed by China replicates the nuclear fusion process carried out by the sun.
• Also, recently scientists in the United Kingdom have achieved a new milestone in producing nuclear fusion energy, or imitating the way energy is produced in the sun.

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