New reactor paves the way to fusion energy
British scientists have built a test reactor that takes a step closer to the dream of fusion energy and its promise of an inexhaustible source of green energy.
It has taken seven years of work and an investment of nearly A$100 million to complete the reconstruction of the MAST Upgrade test reactor, which hopes to pave the way for future fusion power plants. Located at the Culham Centre for Fusion Energy in Oxfordshire, the reactor has already given indications that it may have been worth the effort. It has been activated for the first time, producing the red-hot hydrogen plasma that is the prerequisite for fusion.
MAST Upgrade is designed to produce temperatures of 50-100 million °C. The high temperatures convert the hydrogen into plasma in which the atomic nuclei are separated from the electrons. It is then possible to make the hydrogen nuclei fuse into helium nuclei, a process which corresponds to the activity that takes place inside the Sun, and which liberates huge quantities of energy.
The potential of fusion energy is huge, but so are the challenges. The plasma cannot touch the sides of the reactor, so must be contained within a magnetic field. In most test reactors, this happens in a doughnut-shaped reactor, but MAST Upgrade’s containment zone is more like a cored apple (see also p69).
The goal of MAST Upgrade is not to achieve fusion but to find solutions that can keep the plasma in check and divert surplus heat. These solutions will then be used in other test reactors that move still closer to successful fusion, such as the international ITER reactor that is under construction in France. This should be completed in 2025, and aims to achieve an autonomous fusion process at 150 million °C within 10 years. The ultimate goal is to cross the point at which fusion of the hydrogen cores releases more energy than is supplied from the outside.