08-01-2013, 02:36 PM
INTERNATIONAL THERMO NUCLEAR EXPERIMENTAL REACTOR
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ABSTRACT
International Collaboration for a New Source of Energy. How did the earth survive in 19th century? With the help of raw materials like coal, petroleum.
Can we get the bountiful supply of these raw materials in future? Obviously the answer is "NO”. On which energy should the future mankind depend? It’s the great fusion energy.
The ITER Agreement brings together the People's Republic of China, the European Atomic Energy Community (via EURATOM), the Republic of India, Japan, the Republic of Korea, the Russian Federation and the United States of America in an international collaboration to establish fusion as a new source of energy.
The Members of the ITER Organization will bear the cost of the project through its 10-year construction phase, and its 20-year operational phase before decommissioning. The cost is estimated at 10 billion Euros over the full course of its lifetime. With respect to the construction of the ITER Machine, most of the components will be contributed by the Members in-kind - that is to say the Members will contribute the components themselves, rather than financing for them.
This uses the tokomak device as basic principle.
How does fusion produce energy?
Atoms never rest: the hotter they are, the faster they move. In the core of our Sun, temperatures reach 15 000 000° Celsius. Hydrogen atoms are in a constant state of agitation, colliding at very great speeds. The natural electrostatic repulsion that exists between the positive charges of their nuclei is overcome, and the atoms fuse. The fusion of two light Hydrogen atoms (H-H) produces a heavier element, Helium.
The mass of the resulting Helium atom is not the exact sum of the two initial atoms, however: some mass has been lost and great amounts of energy have been gained. This is what Einstein's formula E=mc² describes: the tiny bit of lost mass (m), multiplied by the square of the speed of light (c²), results in a very large figure (E) which is the amount of energy created by a fusion reaction.
Every second, our Sun turns 600 million tons of Hydrogen into Helium, releasing an enormous amount of energy. But without the benefit of gravitational forces at work in our Universe, achieving fusion on Earth has required a different approach.
In ITER, the fusion reaction will be achieved in a tokomak device that uses magnetic fields to contain and control the hot plasma. The fusion between Deuterium and Tritium (D-T) will produce one Helium nuclei, one neutron and energy.
The Helium nucleus carries an electric charge which will respond to the magnetic fields of the tokomak, and remain confined within the plasma. However some 80% of the energy produced is carried away from the plasma by the neutron which has no electrical charge and is therefore unaffected by magnetic fields. The neutrons will be absorbed by the surrounding walls of the tokomak, transferring their energy to the walls as heat.
ITER STORY
Fossil fuels were the energy source that shaped 19th and 20th century civilization. But burning coal, oil and gas has proved highly damaging to our environment. Carbon dioxide emissions, greenhouse effect gases, and fumes all contribute to the disruption in the balance of our planet's climate.
Global energy consumption is set to triple by the end of the century. And yet supplies of fossil fuels are depleting and the environmental consequences of their exploitation are serious. Two questions loom over humanity today: how will we supply all this new energy, and how can we do so without adding dangerously to atmospheric greenhouse gases?No single nation can face these challenges alone.
ITER OPERATION:
The ITER Organization is bringing together people from all over the world to be part of this thrilling human adventure at Cadarache in the South of France and to contribute to building the ITER device which requires the best people in every domain.working environment is truly multi-cultural and our staff currently represent over 29 different nationalities.
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
In ITER, two independent circuits with cooling water will pass through primary and secondary heat exchangers that lower its temperature before being 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.
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.
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, two independent circuits with cooling water will pass through primary and secondary heat exchangers that lower its temperature before being 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.
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.
What about the risk of an earthquake?
The ITER Tokamak will be made of specially reinforced concrete, and will rest upon bearing pads, or pillars, that are designed to withstand earthquakes. This technology has been used to protect other civil engineering structures such as electrical power plants from the risk of earthquake, and to ensure that their behavior in the case of earthquake satisfies safety requirements. Cadarache, France is classified as an area of moderate seismic activity; the ITER facility will be equipped with seismic sensors around the site to record all seismic activity, however minor.
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.
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. The second safety confinement system comprises 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.