ITER & the Environment
Fusion has the potential to play an important role as part of a future energy mix for our planet. It has the capacity to produce energy on a large scale, using plentiful fuels and releasing no carbon dioxide or other greenhouse gases. ITER is an important step on the road to fusion power plants; in Cadarache, southern France, the project is being planned with great respect for the local environment, in keeping with the aim of producing an environmentally benign form of energy.
The site chosen for the ITER project is a parcel of about 180 hectares located within a forested zone that covers 1,600 hectares. Careful studies were carried out to identify the biodiversity on the ITER parcel and to recommend measures to limit the environmental impact of construction.
Marking trees for protection, 2007. Photo: Agence Iter France.
In all, 39 protected or rare species will benefit from preservation measures on the ITER site, following the recommendations of experts in forestry, fauna, and flora. Two areas have been fenced off permanently as "protected zones"; the Occitan cricket, two species of butterfly, woodlark nesting sites, and rare orchids will all be protected within these areas.
Older trees were singled out for protection prior to site clearing. Some oak trees that were found to house the Great Capricorn beetle—a protected species in Europe—were transferred and grafted onto younger trees in order to preserve the larvae in their trunks. Nesting areas for birds and bats were mapped out, and site clearing activities were authorized outside of nesting periods only.
About half of the 180-hectare ITER site was preserved in its wooded state. Trees cleared from the other half were re-employed for millwork or for heating. In some instances, building plans were modified to accommodate recommendations made by the environmental studies: a projected water treatment plant and control basins were moved to a new area, for example, following the creation of the protected zones. In all, the cost of environmental and protective measures is estimated at two million euros.
Of the 2.5 million cubic metres of earth and rock moved to excavate the ITER platform, over two-thirds were re-employed on site. The remaining material has been stored on site, and will be entirely replanted at the end of construction.
Water & Electricity Consumption
Water is essential to the ITER installation: the terrific heat generated by the fusion reaction inside the ITER machine will be evacuated by a water cooling system. Approximately 3 million cubic metres of water will be necessary per year during the operational phase of ITER. This water will be supplied by the nearby Canal de Provence, and transported by gravity through underground tunnels to the fusion installation. The volume of water needed for ITER represents only 2 percent of the total water transported by the Canal de Provence.
One of four cooling basins on the ITER site.
Electrical supply to the ITER site will be guaranteed by an existing network that feeds the Tore Supra Tokamak—part of the adjacent CEA Cadarache research facility. A one-kilometre extension will be enough to link the ITER machine into the network without changing the current distribution of electrical lines. Operating the ITER Tokamak will require from 120 MW to up to 620 MW of electricity for peak periods of 30 seconds. No disruption to local users is expected.
During ITER Operation
The products of the fusion process are helium, which is inert and harmless, and neutrons, which will lodge in the vessel walls and produce heat and activation of materials. ITER is an experimental facility and is not designed to produce electricity; the heat produced by the fusion reaction will be evacuated by water circulating through the components inside the vacuum vessel and by water circulating in the vacuum vessel walls.
In ITER, cooling water in two independent circuits will pass through primary and secondary heat exchangers that lower its temperature before it is stored in cooling towers where most of the water will evaporate. What remains will pass through cooling basins on the ITER site and be tested for parameters such as temperature (maximum 30°C), pH, hydrocarbons, chlorides, sulphates and tritium. ITER will check the results of these tests before the water is released into the Durance River.
The helium produced by the fusion reaction forms part of a gaseous exhaust that also contains unburned fuel and impurities. This exhaust is extracted continuously from the fusion chamber in order to keep the fusion plasma "clean" and at temperature. A sophisticated gas processing system in ITER will separate the different components of the exhaust gas and recover the fusion fuels in order to reinject them back into the fuel cycle. This "closed loop" fuel cycle minimizes effluents.
Detritiation systems in ITER have been designed to remove tritium from liquids and gases for reinjection into the fuel cycle. Remaining effluents will be well below authorized limits: gaseous and liquid tritium releases to the environment from ITER are predicted to be below 10µSv per year. This is well under ITER's General Safety Objective of 100µSv per year and 100 times lower than the regulatory limit in France of 1,000µSv per year. Scientists estimate our exposure to natural background radiation to be approximately 2,000µSv per year.
For more on tritium and safety at ITER, please visit our FAQ section.