Burning fossil fuels is the number one cause of global warming and has been a major concern for engineers worldwide. Energy demand around the world is expected to double by 2050, and our reliance on fossil fuels – currently 85% – needs to drop dramatically if we are to reduce carbon emissions and limit global warming. The world has scrambled to source for alternative sources for fuel and there has been growing demand for engineers to come up with innovative alternatives that can adequately serve the world’s needs. Located in southern France, the ITER (International Thermonuclear Experimental Reactor) project is the world’s largest bid to harness the power of fusion and engineers are attempting to replicate the Sun here on earth. The focus of the project is to make the long-awaited transition from experimental studies of plasma physics to full-scale electricity-producing fusion power plants. The reactor will work by forcing together two isotopes of hydrogen at such a high temperature that the positively charged atoms can overcome their mutual repulsion and fuse. This fusion will result in an atom of helium plus a highly energetic neutron particle. The energy released by these neutrons will then be captured and used to drive steam turbines and produce electricity. One of the most promising technologies, fusion reactions, are safe, emit neither radioactive waste nor greenhouse gas, and they take up relatively little space. Additionally seawater will provide millions of years of fusion fuel. The project has brought the scientific and political weight of governments representing more than half the world’s population – including the European Union, China, India, Japan, Russia, South Korea and the United States.
At the core of ITER is the Tokamak, a machine in which plasma will be contained in a doughnut-shaped vacuum vessel. The fuel, which is a mixture of two isotopes of hydrogen, is heated to temperatures in excess of 150 million degrees Celsius, forming a hot plasma. The plasma is kept away from the walls by the use of strong magnetic fields which are produced by superconducting coils surrounding the vessel, and by an electrical current driven through the plasma. The magnet system that will be used in ITER will comprise of 18 superconducting toroidal field and 6 poloidal field coils, a central solenoid, and a set of correction coils that magnetically confine, shape and control the plasma inside the vacuum vessel. As the power of the magnetic fields will be extreme, ITER will use superconducting magnets that lose their resistance when cooled down to very low temperatures. Composed of helium and nitrogen refrigerators, a cyroplant will be used to create and maintain low-temperature conditions for the magnet, vacuum pumping and some diagnostics systems. The ITER cryogenic system will be the largest concentrated cryogenic system in the world.
The Tokamak Complex
In July 2010, construction on the scientific buildings and facilities that will house the ITER experiments kicked off. In 2013, the ITER platform had 500 construction workers active and the number is expected to rise to 3000 from 2014 – 2015. A total of thirty nine buildings and technical areas will house the plant systems necessary for the operation of the ITER Tokamak. Fusion experiments are planned to be carried out at the Tokamak Building, the core of ITER. The planned activities are set to begin in November 2020. The Tokamak Building will be 73 meters high (13 meters below the platform level and 60 meters above) and will be among the first buildings completed. Engineers and scientists will progressively integrate, assemble, and test the ITER Tokamak to ensure that all systems function together as well as prepare the ITER machine for operation in 2020. The Tokamak Building will be built on a seismic pit that will be capable of filtering and absorbing the accelerations linked to ground motion. Other buildings that will neighbor the Tokamak Building include cooling towers, electrical installations, a control room, facilities for the management of waste, and the cryogenics plant that will provide liquid helium to cool the ITER magnets. The assembly of the poloidal field coils will take place in the Poloidal Field Coils Winding Facility. It will house the docking stations for the unloading and temporary placement of the superconducting coils, production zones corresponding to the successive steps of the winding and assembly process, and offices.
While the ITER project is one of the most visionary projects ever embarked on, safety concerns are raised constantly and questions have been raised on the feasibility of something that could possibly solve the world’s energy crisis. In 2009, the Local Information Commission (Commission locale d’information, or CLI) which composes of representatives from local government, environmental groups, trade unions, businesses and health professionals was created to act as an interface between ITER and the local population for questions of nuclear safety, radioprotection and the installation’s impact on personnel and the environment.
Through the Tokamak fusion device, the plasma will be able to cool within seconds and the entire reaction will stop. In case of a disruption, the process has been found to be very safe and there is no danger of runaway reaction or explosion. Special reinforced concrete has been developed to ensure that the ITER Tokomak can withstand earthquakes. The facility will also be equipped with seismic sensors around the site to record all seismic activity, however minor. The ITER has also been designed to protect against tritium (a radioactive substance) release and against workers’ exposure to radioactivity. This will be achieved through a multiple-layer barrier system designed for this purpose.
Furthermore, the fusion process will produce no long-lived waste. All waste materials will be treated, packaged, and stored on site. Engineers at ITER will also conduct frequent checks on the installation during construction and operation. Additional audits will also be carried out by the French nuclear authorities.
ITER’s operations are expected to last twenty years. Within this period, its main objectives will be to produce net power and test key technologies, including heating, control, diagnostics, and remote maintenance. This will help scientists gain valuable insights for the design of the next-stage device: a demonstration fusion power plant.