Fusion energy, the energy of the stars, which is generated without producing greenhouse gasses, seems to be the perfect solution to solve the demanding energy needs of mankind – except for one aspect: fusion is created with a nuclear reaction. But, is it the radiation itself which will be dangerous?

The first experiment to prove an energy surplus from a fusion reaction will be ITER. ITER, which also means „the way“ in Latin, is currently under construction in France. 35 countries have joined forces to build the world’s largest tokamak with a major radius of 6.2 meters.

ITER – world widely assembled

This project is also referred to as the biggest puzzle ever. In fact, the pieces of the reactor are coming from all around the world and must be perfectly assembled, millimetre by millimetre. The European Consortium for Fusion Research, EUROfusion, has dedicated almost all of its research toward supporting ITER. The worldwide collaboration for ITER might be problematic in terms of organisation, but it is also a great opportunity. By joining all of these forces, we can create the perfect design for a future fusion power plant. Specialised teams will also take care of safety features to prevent radiation risks to ITER’s staff.

Twelve years of decay

The temperature in a fusion plasma is approximately ten times higher than the heart of the Sun. This heat allows the fusing of two nuclei, deuterium and tritium. Tritium, also known as hydrogen-3, is a radioactive isotope of hydrogen. While deuterium is stable, tritium is not and requires high levels of caution. Fusion experts have planned to build a storage area for tritium, right next to the fusion experiment. But – can fusion be a hazard to people’s health? In particular, the beta particles of hydrogen-3, are unable to penetrate the skin. They can be dangerous when inhaled or ingested via food or water. Additionally, tritium only has a half-live time of about twelve-years.

The tritium cycle

The biggest radiation issue we have come across is related to one of the reaction products: fast neutrons. The neutron, which carries 80 percent of the energy produced in the fusion reaction, is not confined within the plasma. It escapes and penetrates into the components surrounding the plasma chamber, mainly the blanket.

Here the neutrons release their energy which is then used to produce electricity. But a side effect is that the materials near the plasma can become radioactive and must be treated accordingly when the fusion device is being decomissioned.

The blanket inside a fusion reactor should not only be there to absorb the energy in order to produce electricity. It should also ensure that the energy of the neutron is used to “breed” tritium since it occurs somewhat rarely on Earth. Tritium, generated by the neutrons in the blanket, can be removed from the blanket and sent back into the plasma as fuel. Among others, the scientists of EUROfusion are currently investigating such solutions.

It will pay off

Realising a nuclear fusion reactor is a great step for humanity. But, the hunt for fusion energy is both a worldwide collaboration as well as a competition. Both approaches will nevertheless work towards implementing fusion. Several labs around the world, and with a variety of features are studying the different ways to create stable fusion plasmas. Competing ideas with a variety of solutions and “lessons learned” will help fusion to be successful. The collaborative approach, on the other hand, brings together people from various backgrounds to work towards a joint solution.

Great achievements have been made for the sake of fusion progress. We now already know how to reproduce, on Earth, the energy that makes the stars shine. There are still some steps left to be taken before fusion energy becomes feasible and the efforts taken to realise it will pay off.

Giovanna Paladin (Picture: private)After achieving my University degree in Chemical and Materials Engineering, I would like to work on biochemical materials research. I am really concerned by how far human knowledge can go, how we are able to grow technologically and ethically. A news diffuser such as EUROfusion which concentrates on topics such as future fusion reactors would play a large role in this.

Giovanna Paladin (20) from Italy is currently based at Padua. (Picture: private)