Fusion power: safe and very low-carbon
Many studies have looked at the potential impact of fusion power on the environment and at the possible risks associated with operating large-scale fusion power plants. The results show that fusion can be a very safe and sustainable energy source.
The initial European Safety and Environmental Assessment of Fusion Power (SEAFP) looked at conceptual designs of fusion power stations and their safety and environmental assessments, including the identification and modelling of every conceivable accident scenario. This research has been extended in subsequent studies.
SEAFP concluded that fusion has very good inherent safety qualities, among which absence of 'chain reaction' and no production of long-lived, highly radiotoxic products. The worst possible accident would not be able to breach the confinement barriers. Even when a hypothesis is done that confinement barriers be breached, any accidental radioactive release from a fusion power station in this case cannot reach the level that would require the evacuation of the local community.
The inherent safety characteristics of a fusion reactor are due to the very low fuel inventory in the reactor during operation and to the rapid cooling that extinguishes the fusion reactions should a malfunction occur.
Of the fuels, lithium and deuterium are not radioactive. However tritium is radioactive with a short half-life of 12.6 years. As tritium is produced and used inside the reactor, no transport of radioactive fuel is needed.
At the end of a fusion power station's working life the radiotoxicity in the reactor chamber and other structural and waste materials will decay rapidly. In less than 100 years the residual activity of these materials would be less than the radiotoxicity found in the waste from a conventional coal-fired power station. Fusion power will not burden society with a long-term toxic waste issue.
Fusion power does not produce any greenhouse gases (GHGs) or other atmospheric pollutants during operation. It offers a route to large-scale baseload energy production with no negative impact on the climate.
The fuel consumption in a fusion power station is extremely low. To generate 7 billion kilowatt hours of electricity, a 1000-megawatt fusion power station would consume about 100 kg of deuterium and three tonnes of lithium per year. This compares to the 1.5 million tonnes of coal in an equivalent fossil-fuel plant.
Fusion offers an almost limitless fuel supply with the fuel found in all parts of the world, and no negative climate change issues.
Safety for ITER
Key aspects of the safety of ITER are effluents and emissions during normal operation, occupational safety of workers at the site, proper storage and treatment of radioactive materials generated during operation and decommissioning, and potential accidents and incidents.
All these aspects were evaluated as part of a Generic Site Safety Report (GSSR) that developed a technical safety basis for the regulatory and licensing of the ITER site.
The GSSR indicates that effluents during normal operation should be less than 1 % of natural background radiation levels. Occupational exposure of workers at the ITER site is estimated to be less than the guidelines set for the next-generation of nuclear (fission) power plants.
For decommissioning, the majority of the radioactive materials should be released from regulatory control in reasonable timescales. It is estimated that 60 % of the material will be below international clearance levels after 30 years, with 80 % available after 100 years.
The GSSR assessments showed that ITER can be constructed and operated safely without significant environmental impacts.
Further site specific studies will continue once the facilities at Cadarache are built and commissioned.