Introduction

Preamble

Producing a large amount of energy safely with very little fuel is the challenge of magnetic fusion.

In theory, the fusion of less than one kilo per day of deuterium and tritium would produce 1,000 MW of electricity continuously, which is what is done today in a thermal power station. with about 5,000 tons of fossil fuels¹. The fuel used for the fusion is abundant and equitably distributed on the planet; it could be produced from seawater.

The fusion of deuterium and tritium (D-T) produces a nucleus of helium, a neutron and releases energy. In a tokamak, the helium nucleus remains confined in the plasma where it gives up its energy by collision. About 80% of the energy produced by the reaction is carried off the plasma by the neutron. It is absorbed by the walls of the tokamak, transforming it into heat. This heat can be recovered to produce electricity.

Nuclear fission and fusion

The nucleus of atoms is composed of neutrons and protons, which hold together thanks to the most intense force of nature: the strong interaction, responsible for "nuclear binding energy". This energy can be released in two ways:

• by breaking heavy nuclei → this is called nuclear fission
• by fusing light nuclei → this is known as nuclear fusion

1. A 1000 MW PWR reactor uses about 25 tonnes of fuel / year.