Unless this lost fossil fuel output is replaced on a large scale by accepted alternatives, the cost, in terms of economic development foregone, will be very high. The origin and nature of these advantages are discussed briefly below. The fusion fuel cycle does not involve any input of radioactive material and does not generate radioactive waste directly, but radioactivity is nevertheless present in the form of the intermediate fuel, tritium, and as parasitic radioactivity generated in structural materials by the absorption of neutrons. There is the freedom, by suitable choices of design and materials, to reduce the radioactive inventory to achieve low hazard potential. Because the safety and environmental friendliness of fusion are grounded largely in passive and inherent features of the design, rather than on highly reliable safety systems, they should be more readily and transparently demonstrable to the non-scientific community.
Fusion also possesses advantages in the area of non-proliferation.
Under IAEA statutes, none of the materials present in a fusion power station are categorised as being of safeguards significance or require Non-Proliferation Treaty controls. However, because fusion neutrons could be used to generate fissile material, fusion power stations will have to be subject to international safeguards. Such safeguards would be much cheaper and easier to enforce than is the case with fission, because one would be looking for fissile or fertile material in an environment where none at all should be present, in contrast to looking for small discrepancies in large inventories. Because of the environmental and safety advantages summarised above, the widespread, intensive, and indefinite deployment of fusion power plants is unlikely to be significantly constrained by problems of public or political acceptability. Neither category of cost can be estimated with any precision for fossil fuels, fission or fusion fifty years hence, but the present understanding is outlined below.