All current nuclear reactors are based on the fission process, in which the nucleus of a heavier atom is split into those of lighter elements in a controlled manner. This process is accompanied with the release of large amounts of energy. Fusion is the opposite process, in which nuclei of relatively lighter atoms, typically those of hydrogen, are fused to make the nucleus of a heavier atom.

Much more energy is released in the fusion process than in fission. The fusion of atoms of two heavier isotopes of hydrogen — deuterium and tritium — for example, to form a helium nucleus produces four times as much energy as is released during the fission of a uranium atom, the kind of which we see in our nuclear reactors.

Quest for fusion energy

Trying to harness energy from fusion reaction is not a new endeavour. Scientists have been making efforts to build a fusion nuclear reactor for several decades, but the challenges are high. Fusion is possible only at very high temperatures, of the order of a few hundred million degrees Celsius, the kind of temperature that exists at the core of the Sun and the stars. Recreating such extreme temperatures is no easy task. The materials that will make up the reactor, too, need to be able to withstand such huge amounts of heat.

There are several other complications. At such high temperatures, matter exists only in the plasma state, where atoms break up into positive and negative ions due to excessive heat. Plasma, which has a tendency to expand very fast, is extremely difficult to handle and work with.

But the benefits of fusion reaction are immense. Apart from generating much more energy, fusion produces no carbon emissions, the raw materials are in sufficient supply, produces much less radioactive waste compared to fission, and is considered much safer.

Over the years, scientists have been able to draw up the plan for a fusion nuclear reactor. It is called ITER (International Thermonuclear Experimental Reactor) and is being built in southern France with the collaboration of 35 countries, including India which is one of the seven partners, alongside the European Union, the United States, Russia, Japan, South Korea and China.

Several small-scale fusion reactors are already being used for research. The one that produced this week’s new record in energy generation is based at the Culhum Centre for Fusion Energy, just outside of Oxford in England. During the record-breaking experiment, the reactor produced 11 megawatts of energy over a five-second period.

The ITER project

Fusion is considered to be the future of energy. It is supposed to liberate the world from the perennial quest for more and more efficient sources of energy. A very small amount of raw material — deuterium and tritium nuclei to begin with — can produce very large amounts of energy in a clean manner. It is also being seen as an answer to the problem of climate change.

In fact, in its early stages, fusion was also seen as an answer to the problem of climate change because it produces zero emissions. The climate crisis, however, has deteriorated rapidly and needs urgent attention, while a practical fusion reactor is still decades away.

Building a fusion reactor has not been easy. The ITER project began in 1985 and the deadline for its first experimental run has been extended several times. According to the current timeline, it is expected to become operational only in 2035. Right now, the reactor is in the machine assembly phase. Over ten million parts, being manufactured and tested in the seven member countries, have to be transported, assembled and integrated.

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Still, ITER is only an experimental project. The energy it will produce — about 500 MW — would not be in the form of electricity that can be used. It will be a technology demonstration machine that will enable the building of futuristic fusion devices that can be run as normally as the fission reactors today. The deployment of fusion energy for electricity generation for our everyday needs might take another few decades after ITER becomes operational.

India joined the ITER project in 2005. The Institute for Plasma Research in Ahmedabad, a laboratory under the Department of Atomic Energy, is the lead institution from the Indian side participating in the project. As a member country, India is building several components of the ITER reactor, while also carrying out a number of experiments and R&D activities related to the project.