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Nuclear Power
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
Nuclear fusion, should it prove technically and economically feasible, would be an ideal energy source for many reasons, including an inexhaustible supply of energy in the hydrogen in the world’s oceans and the lack of any long-lived fission decay products. The main technical difficulty is (a) achieving the high temperatures needed for controlled nuclear fusion and (b) confining the fuel for a long enough time for self-sustaining ignition to occur. In the core of the sun, gravity is able to provide the confinement, but on Earth, the only two known means of achieving confinement are either a magnetic field or inertial confinement. In the latter case, pellets of fuel are bombarded by powerful lasers from many directions, and the pellet heats up so fast that the inertia of its parts prevents it from blowing itself apart before its temperature is raised to the ignition point. In the other technique pioneered by the Russians in their Tokamak reactor, a diffuse plasma is confined using a magnetic field of a toroidal geometry, which keeps it away from the walls of the vessel while energy is added to heat it. Although considerable progress has been made since the first Tokamak, we are still at least a decade away from a commercially viable fusion reactor. The usual way to measure progress in this field is based on the ratio Q=PowerproducedPowerinput,
Introduction
Published in Syed A. Nasar, F.C. Trutt, Electric Power Systems, 2018
Finally, we consider the two forms of nuclear energy: fission and fusion. In fission, nuclei of a heavy element, such as uranium 235 (235U) split, whereas fusion involves the combination of light nuclei such as deuterium. Among fissionable materials, 235U is the most suitable from an environmental standpoint. But 235U is a rare isotope (each 100,000 atoms of uranium contain 711 atoms of 235U). Thus, naturally available nuclear fuel is in very limited supply. This difficulty may be overcome by the use of breeder reactors, in which uranium 238 is transformed into fissionable plutonium 239 by absorbing neutrons. Similarly, thorium 232 is transformed into uranium 233, which is fissionable. In terms of equivalent energy, with the breeder reactor 1 g of uranium 238 will produce 8.1 × 1010 J of heat, which is approximately equivalent to the heat produced by 2.7 metric tons of coal. The cost of production of electrical energy from nuclear fuels is slightly higher than that from fossil fuels.
Physics, science and technology in the future
Published in Kléber Ghimire, Future Courses of Human Societies, 2018
Work on fusion energy started half a century ago. In 1955, before the invention of laser, physicists were predicting that fusion energy would be successfully utilized within 20 years (Bulletin of the Atomic Scientists, 1957, p. 229). However, after six decades of work, the power of fusion is said to be still 20 years away. Experimental reactors of various designs have been in operation for years. Fusion has been achieved for a brief period of time, i.e., less than a second – not enough for sustainable operation. At this moment, one of the efforts to realize fusion-based power is ITER, an international collaboration to build the world’s largest fusion reactor.5 The ITER reactor can produce 500 megawatts of power – about the same output as a coal-fired power plant. But ITER will not generate electricity; it is a physics experiment that should begin in 2019 in France with participation from China, the European Union, India, Japan, South Korea, Russia and the United States. It is an ambitious project with numerous scientific, technological and financial hurdles to cross. Other approaches, notably laser inertial fusion programs, to attain fusion are being tried simultaneously (Dittrich et al., 2014, p. 55001). Physicists are cautiously optimistic and convinced that they will eventually attain fusion, thereby helping to produce an important source of energy in the future.
Polishing and Local Planarization High-Precision HDC Capsules by Four-Cup-Type Technology for Inertial Confinement Fusion
Published in Fusion Science and Technology, 2023
Yansong Liu, Tao Wang, Guo Chen, Jun Xie, Qi Wang, Zhibing He
As we all know, fusion promises to offer a clean, inexpensive, efficient, and sustainable energy.1 The goal of inertial confinement fusion (ICF) is to compress deuterium (D) and tritium (T) in a capsule in high-pressure conditions, such that the DT fuses and releases large amounts of energy.2,3 In indirect-drive ICF, the capsule is placed at the center of a radiation enclosure (hohlraum) and lasers are fired into the hohlraum, depositing their energy and forming an X-ray drive that serves to ablate and implode the fuel-filled capsule.4,5 Therefore, robust targets, especially precision capsules, play an important role in the success of these experiments. Compared with other target materials (glow discharge plasma or beryllium), the high-density carbon (HDC) ablator has superiority in density and X-ray opacity. It can lead to better energy efficiency and implosion stability, which makes the HDC target more robust, and thus makes successful ignition more likely.6,7 For example, more than a 1.3-MJ yield was obtained by the National Ignition Facility (NIF) with a perfect HDC capsule on August 8, 2021 (Ref. 8).
Effect of Hypervapotron Fin Angle on Subcooled Flow Boiling Heat Transfer Performance Under One-Side High-Heat Load Condition
Published in Fusion Science and Technology, 2022
Fusion energy has the necessary characteristics of a future energy source, such as environmentally friendly clean energy, nondepletable energy, and long-term sustainable power generation, and is attracting attention as one of the solutions for current energy problems.1,2 The phenomenon that a high heat flux is applied to the components inside the plasma vessel of a fusion reactor because of the high-temperature plasma is a major concern for system engineers. In particular, the divertor, which is designed to control the plasma power and particle exhaust, is the highest-loaded component with a heat flux of up to 20 MW/m2 under one-side heating conditions under transient conditions.3 Considering that the heat flux loaded to the nuclear power plant core is 1 to 3 MW/m2 and the electrical component heat flux is 10 to 100 kW/m2 (Ref. 3), it is necessary to develop a system with higher cooling performance than the existing commercialized cooling system. Considering the extraordinary heat flux conditions, the design of the plasma-facing components5,6 (PFCs) of a fusion reactor has to take into account not only the properties of the plasma-facing material,4 but also the technological solution for bonding to the heat sink and the limit of water cooling defined by the critical heat flux7,8 (CHF).
Advanced Isotope Separation Technology for Fusion Fuel
Published in Fusion Science and Technology, 2022
Xin Xiao, Henry T. Sessions, Robert Rabun
Nuclear fusion provides enormous energy and could potentially be an invaluable power-producing source when it becomes controllable. The fusing of light atomic nuclei—nuclear fusion—is the similar reaction that has been powering the Sun and stars since their formation. The concentration of D2O in water is 155 parts per million (ppm). Each liter of seawater could produce the energy equivalent of 300 L of gasoline from D-D fusion. The easiest nuclear fusion reaction is deuterium-tritium (D-T) fusion; however, naturally occurring tritium is extremely rare on Earth. For use in sustained controlled nuclear fusion, tritium needs to be produced by breeding and purification processes. In the present design of nuclear fusion reactors, tritium has a low burnup rate, and therefore, a large portion of the D-T fuel will be recycled. One step in the recycling process will be hydrogen isotope separation.