Joint European Torus Shuts Down After 40 Years, Delivers Final Plasma as Part of Decommissioning Project

Scientists have begun decommissioning Joint European Torus (JET), one of the world's pioneering nuclear-fusion reactors, four decades after it started its operations.

Breakthrough in Fusion Energy

The Joint European Torus was a magnetically confined plasma physics experiment based in the UK Atomic Energy Authority's (UKAEA's) Culham Centre for Fusion Energy. This machine is an experimental nuclear fusion device where temperatures can reach levels ten times higher than the center of the Sun.

It was in 1979 when its foundation stone was laid through the collaboration of 11 nations, including the UK, Switzerland, Sweden, Ireland, Denmark, West Germany, Netherlands, France, Luxembourg, Italy, and Belgium.

JET's first pulse occurred on June 25, 1983, and has since become the world's largest magnetic fusion experiment. The findings in these experiments will support the development of the International Experimental Thermonuclear Reactor (ITER), a $22-billion fusion reactor built near Saint-Paul-lez-Durance in Cadarache, France.

ITER aims to prove the potential of fusion as an energy source in the 2030s. JET provides experts with informed decisions on the kind of materials to build ITER with and the type of fuel to use. It also has a crucial role in predicting the behavior in bigger experiments.

Over the years, JET has achieved several landmarks, holding the record of being the largest reactor of its type until Japan's Torus-60 Super Advanced (JT-60SA) fusion reactor began operating in November 2023. It also achieved the world's first controlled release of fusion energy.

Tritium was first introduced into the JET in 1991 and set a record thermal power output of 16MW in 1997. In 2022, the machine doubled its previous records by producing 59 megajoules of heat energy from fusion within five seconds, smashing the record for the amount of energy created through fusion.

JET Decommissioning and Repurposing

After 40 years of groundbreaking research, the JET has performed its final experiments. On December 18, 2023, the pioneering nuclear fusion reactor delivered pulse 105,842.

JET's decades of research have played a vital role in accelerating the development of fusion energy, but its facility will now move on to the next phase of its life cycle.

The decommissioning and repurposing project will last until around 2040 to define the full life cycle of a fusion power plant. The decommissioning will analyze what has happened to the reactor material and how they have changed.

According to UKAEA, the program will help maintain other fusion reactors better. The agency also notes that the reactor's final day of plasma continued to push scientific boundaries, first attempting an inverted plasma shape for the first time before aiming electrons at the inner wall to improve understanding of damage mechanisms and beam control.

Between now and 2027, the fusion program includes the development of a new Spherical Tokamak for Energy Production (STEP) prototype fusion energy plant in Nottinghamshire.

To fund the first phase of STEP, the government is providing $280 million (220 million pounds) to allow UKAEA to produce a concept design by 2024. The agency aims to have a fully evolved design and approval by 2034, enabling the construction to begin in the following years.

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