NUCLEAR FUSION - IAS Gyan

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Context

Scientists in the United Kingdom said they have achieved a new milestone in producing nuclear fusion energy, or imitating the way energy is produced in the sun.

Nuclear Fusion

Nuclear fusion is defined as the combining of several small nuclei into one large nucleus with the subsequent release of huge amounts of energy.
Nuclear fusion powers our sun and harnessing this fusion energy could provide an unlimited amount of renewable energy.

Nuclear Fission

Fission is the process of splitting a nucleus in two.
Inside each uranium fuel pellet, there are millions of uranium nuclei.
When these nuclei are split, a huge amount of energy is released.
Some of this energy is from radiation, but the biggest source is kinetic energy.
This is the energy that produces heat inside a reactor, which in turn is used to generate steam, and ultimately creates electricity.

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

Fusion is much better than fission in a number of ways. Firstly, nuclear fusion requires less fuel than fission.
On top of that, 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.
Furthermore, 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 don’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.
Today, we conduct fusion reactions in a machine called the Tokamak.
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.

The recent experiment

Deuterium and tritium, which are isotopes of hydrogen, are heated to temperatures 10 times hotter than the centre of the sun to create plasma.
This is held in place using superconductor electromagnets as it spins around, fuses and releases tremendous energy as heat.
The energy was produced in a machine called a tokamak, a doughnut-shaped apparatus.

Significance

The record and scientific data from these crucial experiments are a major boost for the ITER.
The International Thermonuclear Experimental Reactor (ITER) is a fusion research mega-project supported by seven members — China, the European Union, India, Japan, South Korea, Russia and the U.S. — and based in the south of France.
It seeks to further demonstrate the scientific and technological feasibility of fusion energy.