ITER & Safety
Safety is a top-priority issue for ITER. We are concerned about the safety of the project, staff and workers on site, the local population and the environment. French nuclear regulations have been applied throughout the design phase of the project, and shall continue to be applied during construction, operation, and decommissioning.
How safe is fusion? In a tokamak fusion device, the quantity of fuel present in the vessel at any one time is sufficient for a few-seconds burn only. It is difficult to reach and maintain the precise conditions necessary for fusion; any disruption in these conditions and the plasma cools within seconds and the reaction stops, much in the same way that a gas burner is extinguished when the fuel tap is turned off. The fusion process is inherently safe; there is no danger of run-away reaction or explosion.
Are there specific measures for handling radioactive tritium? Based on feedback from the European tokamak JET and from other research laboratories, the most modern and efficient safety measures for the handling of tritium have been incorporated into the ITER design. Tritium is a radioactive substance that also has applications in medicine and technology; the techniques for the safe storage and handling of tritium are well developed. ITER has been designed to protect against tritium release and against workers' exposure to radioactivity.
ITER safety processes will comply with French and international regulations. The ITER installation is classed as a "basic nuclear installation" by French authorities. A successful Public Enquiry was held in 2011, and on 20 June 2012 the ITER Organization was informed in writing by the ASN that—following an in-depth technical inspection—the operational conditions and the design of ITER as described in the ITER safety files fulfilled expected safety requirements. The decree authorizing the creation of the ITER nuclear facility was signed by the French Prime Minister on 10 November 2012, concluding the licensing process for ITER construction.
As part of its responsibilities as a nuclear operator, the ITER Organization will perform regular checks on the installation during construction and operation. French nuclear authorities will also audit and inspect the ITER Organization in application of the regulation.
Technical Provisions for Safety
The confinement of tritium within the fuel cycle is one of the most important safety objectives at ITER. A multiple-layer barrier system has been designed to protect against spread or release of tritium. The first level of the safety confinement barrier is the vacuum vessel itself: inside this double-steel container, the fusion reaction takes place within a vacuum. All pumps, pipes, valves and instruments leading into the vacuum vessel are highly leak-tight.
Surrounding the first confinement system is a second level of security comprising all vessels or systems that surround the vacuum vessel, including buildings as well as advanced detritiation systems for the recovery of tritium from gas and liquids. In ITER, these highly-developed detritiation systems will work efficiently to keep the fusion fuels recycled within a closed system and maintain any releases well below regulatory limits.
A seven-story Tritium Plant will house all the processes related to tritium handling in ITER: reception, storage, recycling, purifying, and extraction.
The products of the fusion reaction are helium, which is a harmless gas, and neutrons. When the highly energetic neutrons interact with the walls of the internal components and the plasma chamber, these materials become activated. In-vessel materials can also become contaminated with small amounts of radioactive dust, mainly beryllium and tungsten, and tritium.
In ITER, confinement of these materials will be based on the Russian doll principle; materials with the highest radioactive content are located in the very centre, surrounded by multiple protective layers. Maintenance and refurbishment of the radioactive elements and components of the tokamak are performed using machines and tools controlled remotely to avoid human exposure to radioactivity. Two metre-thick concrete walls will completely surround the tokamak — this protective layer is known as the bioshield.
During the operational lifetime of ITER, remote handling will be used to refurbish parts of the vacuum vessel. All waste materials will be treated, packaged, and stored on site. The half-life of most radioisotopes contained in this waste is lower than ten years. The fusion reaction will produce no long-lived waste: within 100 years, the radioactivity of the materials will have diminished in such a significant way that the materials can be recycled for use in future fusion plants. This timetable of 100 years could possibly be reduced for future devices through the continued development of 'low activation' materials, which is an important part of fusion research and development today.
At ITER, an integrated safety management system will be put into place to address all potential hazards in compliance with industrial safety regulations. Potential hazards will be addressed specifically by department, and appropriate safety measures put into place. Non-radiological hazards taken into consideration at ITER include fire, exposure to magnetic and electromagnetic fields, exposure to chemicals or cryogenic fluids, and high voltages. To protect workers, access to the Tokamak Building will be strictly forbidden during operation.
Please see our FAQ section for more information on ITER and safety.