Nuclear Fusion: New Record for Energy Output Set

Scientists at the Joint European Torus (JET) facility in the United Kingdom have successfully generated the largest amount of energy ever produced in a fusion reaction. In its final series of experiments, the laboratory produced 69 megajoules of heat energy over five seconds. This breakthrough provides concrete validation for fusion technology just as the scientific community shifts focus to the massive ITER project in France.

Inside the Record-Breaking Run

The achievement occurred during the final operating campaign of the JET laboratory near Oxford. For over 40 years, this facility has been central to global fusion research. In late 2023, researchers pushed the machine to its limits one last time.

The result was a sustained fusion reaction that produced 69 megajoules of energy. To put this specific number in perspective, it beats the previous world record of 59 megajoules, which was set by the same facility in 2021. While 69 megajoules is only enough electricity to power a typical home for a short time or boil roughly 70 kettles of water, the implications for physics are massive.

The critical success factor was the stability of the reaction. Sustaining high power for five seconds demonstrates that the magnetic conditions required to hold superheated plasma in place are understood and replicable.

The Fuel Efficiency

One of the most stunning aspects of this record is the fuel efficiency. To generate that 69 megajoules of energy, the reactor used approximately 0.2 milligrams of fuel. If you were to generate the same amount of energy using fossil fuels, you would need:

• 2 kilograms of brown coal.
• 1.2 kilograms of oil.
• 1.2 kilograms of natural gas.

This immense energy density is why fusion is often viewed as the “holy grail” of clean power generation.

How the JET Reactor Works

The JET facility utilizes a design known as a “tokamak.” You can visualize a tokamak as a large, donut-shaped vacuum chamber. Inside this chamber, gas is superheated until it becomes a plasma.

For fusion to occur, atomic nuclei must collide and fuse together to form heavier atoms. This process releases vast amounts of energy. However, atoms naturally repel each other. To overcome this repulsion, the environment must be incredibly hot and pressurized.

Inside the JET tokamak, the plasma reaches temperatures of 150 million degrees Celsius. This is ten times hotter than the core of the sun. Because no physical material can withstand heat that intense, the plasma is suspended in the center of the donut shape using powerful magnetic fields.

Deuterium and Tritium

The specific record set by JET used a fuel mix of Deuterium and Tritium (often abbreviated as D-T). These are two isotopes of hydrogen.

• Deuterium: This is abundant and can be extracted from seawater.
• Tritium: This is rarer and is currently produced as a byproduct of conventional nuclear fission or manufactured from lithium.

JET is currently the only laboratory in the world capable of handling this specific D-T fuel mix. Most other reactors run on deuterium only because it is easier to handle, even though it produces less energy. Proving that the D-T mix works efficiently at this scale is vital for future power plants.

Passing the Torch to ITER

The JET facility has now concluded its operations and will be decommissioned. However, its data is being handed over to a much larger project called ITER (International Thermonuclear Experimental Reactor).

Located in southern France, ITER is a massive international collaboration involving 35 nations, including China, the European Union, India, Japan, Korea, Russia, and the United States. ITER is essentially a scaled-up version of JET.

Here is how the two compare:

• JET: Designed to prove fusion can happen. It required more energy to run the magnets and heaters than it produced in fusion output.
• ITER: Designed to prove “net energy.” Its goal is to produce 500 megawatts of fusion power for every 50 megawatts of input heating power (a gain factor of 10).

The success at JET suggests that the physics modeling used to design ITER is accurate. If JET had failed to reach these numbers, it would have signaled a potential design flaw in the much more expensive ITER project.

The Difference Between Fission and Fusion

It is important to distinguish this technology from the nuclear power plants currently in operation. Current nuclear plants use fission.

Fission involves splitting heavy atoms like uranium. This creates a chain reaction that produces heat. While it is low-carbon, it carries risks of meltdowns and produces long-lived radioactive waste that must be stored for thousands of years.

Fusion joins light atoms like hydrogen. The benefits include:

1. Safety: There is no risk of a meltdown. If the containment system fails, the plasma cools down instantly and the reaction stops.
2. Waste: Fusion does not produce high-level, long-lived radioactive waste. The reactor components may become radioactive over time, but the materials can be recycled or disposed of within 100 years.
3. Fuel Supply: The fuel sources (water and lithium) are globally available and virtually inexhaustible.

Challenges Remaining

Despite the success of 69 megajoules, commercial fusion energy is not happening tomorrow. Significant engineering hurdles remain before you can plug your toaster into a fusion-powered grid.

Heat Exhaust: Handling the immense heat that escapes the magnetic cage is difficult. Scientists are testing new metals, such as tungsten, and different divertor shapes to prevent the reactor walls from melting.

Tritium Breeding: Because tritium is rare, future commercial reactors will need to “breed” their own fuel. They will do this by lining the reactor walls with lithium. When neutrons from the fusion reaction hit the lithium, it converts into tritium. This process has not yet been proven at a commercial scale.

Magnet Technology: Maintaining the magnetic fields requires massive amounts of electricity. Newer projects are looking at High-Temperature Superconducting (HTS) magnets to make the containment more efficient.

Frequently Asked Questions

When will fusion energy be available for homes?

Most experts predict that fusion energy will supply the electrical grid in the second half of this century. While ITER plans to achieve full plasma operations in the 2030s, a demonstration power plant (often called DEMO) would follow in the 2040s or 2050s.

Is the JET record a “net energy” gain?

No. The 69 megajoules of output was less than the energy required to heat the plasma and run the magnets. JET was not designed to achieve net energy gain. Its purpose was to study the behavior of the plasma. Net energy gain is the primary goal of the ITER project.

Can a fusion reactor explode like a nuclear bomb?

No. A fusion reactor contains very little fuel at any given moment (less than a gram). The conditions required for fusion are so specific that any disturbance (like a leak or equipment failure) causes the reaction to stop immediately. It is physically impossible for a fusion reactor to cause a runaway chain reaction.

Who funded the JET project?

JET was funded by the European Commission through the Euratom Research and Training Programme. It was operated by the UK Atomic Energy Authority (UKAEA).