Safety

Fusion power plants will be inherently safe. Although the plasma in a fusion power plant will have a volume of 1000 cubic meters or more, the total amount of fusion fuel in the vessel is very small: only few grams, enough for just a short time of operation. If the fuel supply is closed, the reaction stops without problems within seconds. Fusion is not a chain reaction and can therefore not run out of hand: in the normal situation, any deviation from the optimum plasma configuration leads to a decrease in temperature or density and thus to a decrease of energy production.

The intermediate fuel, tritium, is a radioactive substance, and fusion power plants are constructed in such a way that a safe handling of the tritium is ensured, which is subject to appropriate laws and regulations. Techniques and expertise to handle tritium safely already exist.

As tritium is produced inside the plant in a closed circuit, the total amount of tritium present can be kept as low as possible (a few kg), and outside the plant no transport of tritium is needed, except when a new fusion power plant is constructed.

Environmental impact

Although the products of the fusion process (helium and neutrons) are not radioactive, the structural materials of the vessel are activated by the neutrons. If proper materials are used, the half-life of most radioisotopes contained in such waste can be limited to about 10 years, meaning that after a period of e.g. 100 years the radioactivity drops to a 10.000th of its initial value, and that most materials can be largely recycled. The design of new, so called low-activation materials that are needed for this aim, is an important and active part of the international fusion research. Moreover, fusion produces no actinides, which form the long-lived waste of fission power plants.