21-02-2010, 12:25 PM
ITER - the way to new energy
ITER â€œINTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR.
ITER is a large-scale scientific experiment that aims to produce electricity from NUCLEAR FUSION.
Q = 10 represents the scientific goal of the ITER project: to deliver ten times the power it consumes.
The same principle of sun is used to produce heat in ITER plant.
WHAT IS FUSION
Fusion is the process at the core of our Sun.
In the core of our Sun, temperatures reach 15 000 000Ã‚Â° Celsius. Hydrogen atoms are in a constant state of agitation, colliding at very great speeds.
The fusion of two light Hydrogen atoms (H-H) produces a heavier element, Helium. and release tremendous amounts of energy in the process.
ITER will use Deuterium-Tritium (D-T) combination of elements to fuel the fusion reactor.
Deuterium can be distilled from all forms of water. It is a widely available, harmless, and virtually inexhaustible resource.
Tritium is a fast-decaying radioelement of Hydrogen which can be produced during the fusion reaction through contact with Lithium.
ITER - The World's Largest Tokamak
ITER is based on the 'tokamak' concept of magnetic confinement, in which the plasma is contained in a doughnut-shaped vaccum vessel.
Tokamak is an experimental arrangement for controlled nuclear fusion.
Strong magnetic fields are used to keep the plasma away from the walls.
The fuel - a mixture of Deuterium and Tritium, two isotopes of Hydrogen - is heated to temperatures in excess of 150 millionÃ‚Â°C causing fusion to form hot plasma.
Once fusion has begun, high energy neutrons will radiate from the reactive regions of the plasma.
Energy absorbed from the fast neutrons is extracted and passed into the primary coolant.
This heat energy is used to power an electricity-generating turbine in a real power plant to produce electricity.
The Vacuum Vessel is a hermetically-sealed steel container inside the cryostat that houses the fusion reaction and acts as a first safety containment barrier.
In its doughnut-shaped chamber, or torus, the plasma particles spiral around continuously without touching the walls.
The size of the Vacuum Vessel dictates the volume of the fusion plasma.
The ITER Magnet System comprises
18 superconducting Toroidal Field.
6 Poloidal Field coils.
a Central Solenoid.
A set of Correction coils that magnetically confine, shape and control the plasma inside the vaccum vessel.
The Blanket covers the interior surfaces of the vacuum vessel, providing shielding to the Vessel and the superconducting magnets from the heat and neutron fluxes of the fusion reaction.
Located at the very bottom of the vacuum vessel.
Its function is to extract heat and Helium ash â€ the products of the fusion reaction. It permits the recycling of fuel
It will comprise two main parts: a supporting structure made primarily from stainless steel and the plasma facing component made of Tungsten.
Vacuum pumping is required prior to starting the fusion reaction to eliminate all sources of organic molecules that would otherwise be broken up in the hot plasma.
Mechanical pumps and powerful cryogenic pumps evacuate the air out of the Vessel and the Cryostat until the pressure inside has dropped to one millionth of normal atmospheric pressure
The Cryostat is a large, stainless steel structure surrounding the vacuum vessel and superconducting magnets, providing a super-cool, vacuum environment.
It is made up of two concentric walls connected by horizontal and vertical ribs.
The low-density gaseous fuel is introduced into the Vacuum Vessel by a gas injection system. An electrical current is applied to the system which causes the gas to break down electrically, become ionized, and form plasma.
A second fuelling system- a pellet injector ,highly-efficient ice maker. An extruder punches out several millimeter-sized Deuterium-Tritium ice pellets that are propelled by a gas gun up to 3600 km/h - fast and cold enough to penetrate deep into the plasma core.
External Heating Systems
Neutral Beam Injectors are used to shoot uncharged high-energy particles into the plasma where, by way of collision, they transfer their energy to the plasma particles.
Ion Cyclotron Resonance Heating (ICRH)in which energy is transferred to the ions in the plasma by a high-intensity beam of electromagnetic radiation with a frequency of 30 to 50MHz.
Electron Cyclotron Resonance Heating (ECRH) heats the electrons in the plasma with a high-intensity beam of electromagnetic radiation at a frequency of 100 to 200MHz
Water from the nearby Canal de Provence will be used to remove heat from the Vacuum Vessel and its components.
The Cooling Water System is separated into two closed heat transfer circuits plus a Cooling Tower open circuit.
ITER will have a steady state distribution system to supply the electricity needed to operate the entire plant .
A second pulsed power system will be used during plasma operation to provide the superconducting magnet coils and the heating and current drive systems with the large amount of power that they need .
It will deliver ten times the power it consumes .
It could provide a large-scale energy source with basic fuels which are abundant and available everywhere.
It has very low global impact on the environment â€œ no CO2 greenhouse gas emissions.
Day-to-day-operation of a fusion power station would not require the transport of radio-active materials.
There is no long-lasting radioactive waste to create a burden on future generations .
Cost is high- about 10billion euros.
The implementation of the plant will take 30-50 years.
Intense neutron bombardment may damage the superconducting magnets.
ITER will be a major experimental facility to demonstrate the scientific and technical feasibility of fusion power. Low power output of Solar, wind, and hydroelectric power plants and highly radioactive products of fission reactor can be compensated by ITER in the near future. ITER will allow scientists to explore the physics of a burning plasma at energy densities close to that of a commercial power plant, and delivering commercially available electricity from fusion to the grid. Thus, ITER may contribute to a hydrogen-based economy of the future.