Plasma Confinement Facts Magnetically confined plasmas have achieved temperatures 10 times hotter than the core of our sun. ITER will be the first burning plasma in the world. It aims to generate megawatts of fusion power—10 times more power than will be injected. NIF is the most energetic laser in the world with 2 megajoules of light energy the energy consumed by 20, watt light bulbs in one second delivered in 16 nanoseconds.
Burning Plasma Organization Scientific terms can be confusing. Creating inertial confinement fusion and energy gain in the NIF target chamber will be a significant step toward making fusion energy viable in commercial power plants.
Because modern thermonuclear weapons use the fusion reaction to generate their immense energy, scientists will use NIF ignition experiments to examine the conditions associated with the inner workings of nuclear weapons see Stockpile Stewardship. Ignition experiments also can be used to help scientists better understand the hot, dense interiors of large planets, stars and other astrophysical phenomena see Discovery Science. There are two ways to achieve the temperatures and pressures necessary for hydrogen fusion to take place:.
Microwaves, electricity and neutral particle beams from accelerators heat a stream of hydrogen gas. This heating turns the gas into plasma. This plasma gets squeezed by super-conducting magnets, thereby allowing fusion to occur. The most efficient shape for the magnetically confined plasma is a donut shape toroid. A reactor of this shape is called a tokamak. The ITER tokamak will be a self-contained reactor whose parts are in various cassettes. There they create new tritium from lithium in the blanket to compensate for the tritium consumed, and they also produce heat from the neutron-lithium reaction.
The tritium must be extracted from the blanket, recycled, and re-injected into the plasma — making blanket design another formidable challenge. Imagine a large deuterium-tritium power reactor and its associated blanket producing electricity at a rate of 1, megawatts roughly the size of nuclear fission plants and coal plants today , running 90 percent of the time, and converting into electricity 40 percent of the fusion energy produced in the plasma and blanket.
Approximately 80 kilograms of deuterium and kilograms of tritium would be consumed each year. A future global energy system with a central role for fusion, say a world with 1, one-thousand-megawatt plants, would consume 80, kilograms of deuterium per year. In the absence of tritium regeneration from lithium in the blanket, it would also consume , kilograms of tritium per year. The job of isolating sufficient deuterium for fusion reactors is not difficult.
Thus, a single such plant could produce sufficient deuterium for more than a thousand large one-thousand-megawatt fusion plants. By contrast, tritium is radioactive and essentially is not found on Earth, so that tritium management is a major task for fusion.
A mature fusion industry will require that more tritium is generated in the blankets than is consumed in the plasmas. But it is unclear how the tritium needed for the first fusion power plants will be produced. In parallel with magnetic confinement fusion, inertial confinement fusion is being investigated, which seeks to drive fusion reactions by compressing matter to very high densities with laser beams that converge on small pellets.
The same fusion reactions are involved in both cases, but the obstacles in the path to commercialization of fusion energy are entirely different. Back to Top. Estimates of the cost of a fusion power plant vary widely, which is hardly surprising since many important determinants of the cost are not known. The costs come in two categories: the cost of the initial capital and the costs to keep the plant running.
The figure below is representative of published cost estimates. Of the total cost of electricity, 73 percent is associated with building the plant, about the same as the percent for coal and nuclear fission plants. But some of the remaining costs are uniquely important for fusion. The two striped components in the figure below, totaling 16 percent of the costs, are for periodic replacement of important structural components whose performance has been compromised as a result of neutron bombardment.
Neutron bombardment weakens a structural material not only by displacing atoms from their sites but also by producing helium via nuclear reactions at these sites, resulting in swelling. Looming over fusion is the concern that component replacements will not be straightforward and will require costly plant shutdown for months at a time. Components of the total cost of electricity produced by a magnetic confinement fusion reactor, shown as a percent of total cost.
The two components shown with stripes are costs for replacement of critical elements of the reactor whose lifetime, due to neutron bombardment, could be much shorter than the rest of the reactor.
Source: [A]. A second threat to nearly continuous operation of a fusion power plant comes from the possibility that severe plasma instabilities will drive the hot plasma into a wall and lead the reactor to shut itself down automatically to avoid significant damage.
Fusion research — since its inception — has sought to control plasma instabilities; the additional instabilities expected from a burning plasma could make the control of a fusion reactor even more daunting. The extent to which fusion could contribute to global electricity production in this century is highly uncertain.
For example, the future cost of nuclear fission power depends on whether substantial extra costs will be incurred that reflect broad public mistrust of the technology.
Fusion is a low-carbon energy source, and strong climate policy for example, a high tax on carbon dioxide emissions into the atmosphere will disadvantage coal, oil, and gas, relative to fusion and other non-fossil energy sources. However, a strong carbon policy may also lead to low-carbon versions of fossil-fuel power plants, called carbon dioxide capture and storage CCS power plants, where much of the carbon dioxide produced at the plant ends up deep below ground in geological formations rather than in the atmosphere.
A representative market-share study of the 21st-century global energy system assumed that fission and fusion by mid-century will have nearly the same cost and determined that:. Two extreme cases are shown in the figure below. In Panel II, the world maintains a tough climate policy, fission is more expensive than in Panel I, and CCS deployment is limited by geological storage space. Additionally, total electricity production is higher in Panel II because electricity is favored over the direct use of fuels when there is a carbon tax — think, for example, of electric cars.
Even for Panel I, fusion produces substantial electricity at the end of the century: four trillion kilowatt-hours each year — approximately the scale of the deployment of nuclear fission power today.
Respectively, in Panels I and II, about versus 5, one-thousand-megawatt fusion plants are on-line in The risks from fusion and fission power can be compared in at least these four ways: nuclear weapons proliferation, radioactive waste, reactor accidents, and terrorist or military attack.
In general, the risks from fusion power are smaller.
0コメント