Nuclear fusion process (environmental impact)
The nuclear fusion process involves the reaction between light atomic nuclei to form a heavier nucleus, releasing significant amounts of energy in the process. This technology has the potential to generate a large amount of power with minimal environmental impact, as it produces no greenhouse gas emissions and significantly less radioactive waste compared to traditional nuclear fission reactors. The primary fuels for fusion, deuterium and tritium, are abundant, with deuterium found in seawater. Environmental concerns are relatively low, as the by-products of fusion, mainly helium, are non-toxic and do not contribute to global warming. While tritium is radioactive, it has a short half-life and does not accumulate in the body, posing limited health risks. Key safety features of fusion reactors include the fact that any disruption in the controlled conditions would halt the reaction, preventing catastrophic accidents. However, the potential for some radioactive materials to be created in reactor structures remains a concern, although they typically have shorter half-lives than those produced during fission. Ongoing international collaboration aims to develop commercial fusion reactors, with hopes that advancements may lead to operational facilities by 2050.
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Nuclear fusion process (environmental impact)
DEFINITION: Reaction between light atomic nuclei that produces a heavier nucleus and releases energy
Nuclear fusion can produce much more energy for a given weight of fuel than any other available energy technology. Controlled fusion reactors could generate high levels of power with uninterrupted delivery and no greenhouse gas emissions. The fusion process produces far less radioactive material than fission reactors, and the by-products generated are less damaging biologically. The radioactive wastes produced by fusion reactors would cease to be dangerous after reasonably short periods of time.
Deuterium, the primary fuel used for nuclear fusion, is abundant in seawater. When a atom and a tritium atom, both isotopes of hydrogen, are fused together, helium is formed, with the of a neutron and 17.6 million electronvolts (MEV) of energy. To undergo fusion, the interacting nuclei need kinetic energies on the order of 0.7 MEV to overcome the electrical repulsion between their positive charges. These energies are available at temperatures around 10 million kelvins (18 million degrees Fahrenheit), which poses a major problem for containment of the fusion fuel. In some experiments, the resulting plasma generated by heat from an electrical is contained in the reactor core with appropriately shaped magnetic fields (magnetic confinement). In other experiments, fusion is initiated through the heating and compressing of pellets of the light nuclei with a high-intensity laser beam (inertial confinement). Methods of achieving fusion at lower temperatures, known as cold fusion, continue to be studied, but none has been found that produces more energy than is consumed in the fusion process.
Environmental Advantages and Concerns
The natural product resulting from the fusion of deuterium with tritium is helium, which poses no threat to life and does not contribute to global warming. Although tritium is radioactive, it has a short half-life of twelve years, has a very low amount of decay energy, and does not accumulate in the body. It is cycled out of the human body as water, with a biological half-life of seven to fourteen days. Since fusion requires precisely controlled conditions of temperature, pressure, and magnetic field parameters in order to generate net energy, there is no danger of any catastrophic radioactive accident, as heat generation in a fusion reactor would quickly stop if any of these parameters were disrupted by a reactor malfunction. In addition, since the total amount of fusion fuel in the reactor vessel is very small (a few grams) and the of the plasma is low, there is no of a runaway reaction, because fusion would cease in a few seconds if fuel delivery were stopped.
Because of the generation of high-energy neutrons in the deuterium-tritium reaction, the typical structural materials of fusion reactors, such as stainless steel or titanium, tantalum, and niobium alloys, will become radioactive when bombarded by the neutrons. The half-lives of the resulting are typically less than those generated by nuclear fission. Most of this radioactive material would reside in the fusion reactor core and would be dangerous for about fifty years. Low-level wastes would be dangerous for about one hundred years. Since the choice of materials used in a fusion reactor is quite flexible, low-activation materials, such as vanadium alloys and carbon fiber materials, that do not easily become radioactive can be used.
Most fusion reactor designs use liquid lithium as a coolant and for generating tritium when it is bombarded by neutrons coming from the fusion reaction. Because lithium is highly flammable, a fire could release its tritium contents into the atmosphere, posing a risk. Estimates of the amount of tritium and other radioactive gases that might escape from a typical fusion power plant indicate that they would be diluted to safe levels by the time they reached the perimeter fence of the plant.
Another safety and environmental concern associated with fusion reactors is the potential that the neutrons generated in a fusion reactor could be used to breed plutonium for an atomic bomb. In order for a reactor to be used in this way, however, it would have to be extensively redesigned; thus the plutonium production would be very difficult to conceal. The tritium produced in fusion reactors could be used as a component of hydrogen bombs, but the likelihood is minimal.
Development of Commercial Fusion Reactors
Despite fusion research that started during the 1950s, a commercial fusion reactor will most likely not be available until at least 2050. Several deuterium-tritium fusion reactors using the tokamak design have been built as test devices, but none of them produce more thermal energy than the electrical energy consumed.
As of 2023, the United States, twenty-seven European Union countries, China, India, Japan, Korea, and the Russian Federation were collaborating to build the world's largest magnetic fusion device, the International Thermonuclear Experimental Reactor (ITER), which was being constructed in southern France. ITER is planned to fuse atomic nuclei at extremely high temperatures inside a giant electromagnetic ring. Funded mostly by the US Department of Energy, the Lawrence Livermore National Laboratory is a research and development center in Livermore, California. The center's main responsibility as of 2024 was national security, ensuring the safety and security of the country's nuclear weapons. It was also working on a high-energy laser system that could heat hydrogen atoms to temperatures that exist in the cores of stars. Such a system would provide the ability to produce more energy from controlled, inertially confined nuclear fusion than is necessary to produce the reaction.
Bibliography
Ball, Philip. "What Is the Future of Fusion Energy?" Scientific American, 1 June 2023, www.scientificamerican.com/article/what-is-the-future-of-fusion-energy/. Accessed 21 July 2024.
Barbarino, Matteo. "What Is Nuclear Fusion?" International Atomic Energy Agency, 3 Aug. 2023, www.iaea.org/newscenter/news/what-is-nuclear-fusion. Accessed 21 July 2024.
Braams, C. M., and P. E. Stott. Nuclear Fusion: Half a Century of Magnetic Confinement Fusion Research. Philadelphia: Institute of Physics Publishing, 2002.
Bryan, Jeff C. Introduction to Nuclear Science. Boca Raton, Fla.: CRC Press, 2009.
McCracken, Garry, and Peter Stott. Fusion: The Energy of the Universe. Burlington, Mass.: Elsevier Academic, 2005.
Seife, Charles. Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking. New York: Viking Press, 2008.