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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,
The future
Published in R.J. Pentreath, Nuclear Power, Man and the Environment, 2019
If fusion is to be considered as a source of power it is also important to realize that the total, useful, energy recovered must be at least sufficient to maintain the temperature of the reaction. This criterion is expressed in terms of the number of reacting nuclei per unit volume, and the time during which the reaction takes place. There are, therefore, three basic requirements for the construction of a fusion reactor as a source of power: an optimum number of nuclei per unit volume – about 1014cm-3; a temperature in excess of 108° C; and the sustainment of these conditions for periods of several seconds. Sustaining, and thus confining, the reaction is one of the biggest difficulties. At present the only known means of confining a high-temperature plasma is the use of magnetic fields. These confine the plasma because it is difficult for charged particles to cross them although there is nevertheless, a partial ‘mixing’ between the plasma and the magnetic fields and this causes the particles to spiral along the lines of force.
Nuclear Power
Published in Robert Ehrlich, Harold A. Geller, Renewable Energy, 2017
Robert Ehrlich, Harold A. Geller
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 (1) achieving the high temperatures needed for controlled nuclear fusion and (2) 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
Reconfiguration of an Electrothermal-Arc Plasma Source for In Situ PMI Studies
Published in Fusion Science and Technology, 2021
E. G. Lindquist, T. E. Gebhart, D. Elliott, E. W. Garren, Z. He, N. Kafle, C. D. Smith, C. E. Thomas, S. J. Zinkle, T. M. Biewer
Fusion reactors produce incredibly harsh environments where plasma-facing materials must withstand cyclic high thermal loads, plasma exposure, and neutron irradiation. Single- and multivariable testing facilities capable of producing ITER- or reactor-relevant high heat flux and high particle flux are necessary. Additionally, most plasma-material interaction (PMI) studies rely on in vacuo, postmortem, or ex situ analyses. With these techniques, in vacuo, ex situ, and postmortem analyses are helpful, but time-dependent effects, such as gas diffusion, thermal change, or deposition, can be lost in the process of getting the sample to the analysis device. Also, the design of high heat flux surfaces in tokamaks, such as the divertor, includes cooling channels under the surface tiles. Quantifying erosion in situ will be necessary to prevent breaching the coolant channels. To this end, diagnostics are being developed that can measure in situ surface morphology changes under steady-state and transient-level heat fluxes and particle fluxes.
Applicability of a 100-mL Polyethylene Vial for Low-Level Tritium Measurement Using a Low-Background Liquid Scintillation Counter
Published in Fusion Science and Technology, 2020
Yoshinari Oshimi, Mayu Ohki, Misato Nagano, Takuyo Yasumatsu, Masanori Hara, Satoshi Akamaru, Masato Nakayama, Miki Shoji
Liquid scintillation counting has been widely used for measuring tritium in liquid samples.1 It has a high counting efficiency and high sensitivity for tritium measurements. Tritium concentrations surrounding a nuclear power plant are routinely measured using a liquid scintillation counter (LSC). On March 11, 2011, the Fukushima Daiichi nuclear power plant was damaged by a tsunami caused by a large earthquake. Various radionuclides containing tritium were released from the reactors to the environment,2 and released tritium spread into the water.3,4 After the incident at the Fukushima Daiichi nuclear power plant, tritium was distributed, and elevated concentrations were observed in Japan. Nuclear fusion reactors, which burn a mixture of tritium and deuterium gases for fuel, are attractive as a new energy resource. In the future, a nuclear fusion reactor will be used as an energy source, and huge amounts of tritium will be handled. Effective tritium measurements in environmental samples will be indispensable for ensuring social acceptance of this nuclear technology.
Progress Toward a Compact Fusion Reactor Using the Sheared-Flow-Stabilized Z-Pinch
Published in Fusion Science and Technology, 2019
Eleanor G. Forbes, Uri Shumlak, Harry S. McLean, Brian A. Nelson, Elliot L. Claveau, Raymond P. Golingo, Drew P. Higginson, James M. Mitrani, Anton D. Stepanov, Kurt K. Tummel, Tobin R. Weber, Yue Zhang
Progress toward creating a viable fusion reactor requires resolving outstanding scientific questions and engineering challenges. The Fusion Z-pinch Experiment (FuZE) is investigating the use of a Z-pinch as a platform for intermediate density fusion and has produced compelling results. This approach leverages the high density and high beta plasma confinement of a Z-pinch to design a compact, low-cost reactor that would require a shorter development path than larger, magnetically confined concepts such as tokamaks. Before this design can be used, however, the physics of scaling the Z-pinch to fusion conditions must be further explored, and engineering challenges such as material degradation and shielding must be overcome. This paper reports on experimental findings from FuZE and a concept for a Z-pinch–based reactor.