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Geothermal Energy
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
Spallation is the process by which fragments of a piece of material are ejected due to either impact or stress. Spallation drilling involves no drill bit that can wear out due to contact with the rock. Instead, a flame jet makes contact with a small area of the rock at the bottom of the borehole, and the induced thermal stresses in the rock cause small fragments of it (spalls) to be ejected.1 The fragments are small enough that the injection of high-pressure water carries them up the water-filled drilling pipe. Oxygen must be supplied to allow combustion underwater in a similar manner as done in underwater welding. The spallation technique has been demonstrated and found to work well, and it is likely to be a significant improvement over conventional drilling methods, in terms of both speed and cost—especially if it can make the cost dependence on depth linear rather than exponential (Figure 6.12).
Secondary Radiation Production and Shielding at Proton Therapy Facilities
Published in Harald Paganetti, Proton Therapy Physics, 2018
Spallation is the emission of a large number of nucleons and fragments caused by the interaction of a high-energy proton or neutron with kinetic energies from ~100 MeV to several GeV, with a target nucleus. It includes the intranuclear cascade and de-excitation and plays an important role in activation.
Experiments in thermal spallation of various rocks
Published in Zikmund Rakowski, Geomechanics 93, 2018
R.E. Williams, R.M. Potter, Stefan Miska
In order to achieve these goals, the following objectives were set forth: To test the spallability of rocks encountered in oil and gas drilling and in producing blast holes for mining. This work would be done in an outdoor laboratory using rock specimens and insitu.To improve the design of thermal spallation drilling equipment, particularly as it pertains to the drilling head itself.To demonstrate thermal spallation to prospective users with the intention of establishing a collaborative industry/university research initiative.To provide well documented drilling experiences which can be analyzed theoretically.To find commercial applications for this work that would demonstrate the feasibility and the economic advantages of spallation.
Reactor-Driven Neutron Sources from the 207Pb(γ,n) and 205Tl(γ,n) Reactions
Published in Nuclear Technology, 2023
Sylvian Kahane, Yair Ben-Dov (Birenbaum), Raymond Moreh
Accelerators can also be used to provide charged particles (protons or deuterons, primarily) for either nuclear reaction–based neutron sources, such as the 7Li(p,n)7Be reaction (generating neutrons in the 0- to 1.3-MeV range7), or spallation-based neutron sources like ISIS (Ref. 8), SNS (Ref. 9aHandbook of Spallation Research is a detailed and comprehensive reference to spallation.), and n_TOF (Refs. 10 and 11). Finally, neutrons can be produced by fission reactions, either in critical assemblies or via nuclei that decay by spontaneous fission, such as 252Cf (Ref. 1).
Preliminary Neutronics Study of an Accelerator-Driven Molten Spallation Target–Molten Lithium Source of Tritium
Published in Fusion Science and Technology, 2023
Michal Cihlář, Slavomír Entler, Tomáš Czakoj, Václav Dostál, Jan Prehradný, Pavel Zácha
The particles, usually protons or deuterons, are accelerated in a particle accelerator and directed to the molten spallation target. The accelerated particles cause a spallation reaction on nuclei of lead or bismuth. The spallation reaction is a fragmentation of a heavy nucleus into small fragments and neutrons. More about the spallation reactions theory, experiments, and utilization can be found in the Handbook of Spallation Research: Theory, Experiments and Applications14 and other works.15,16 From the spallation reaction, about 20 to 30 spallation neutrons commonly are created depending on incident proton energy.
Conceptualization of the Micro Research Reactor Cooled by Heat Pipes (MRR-HP), Part-I: neutronics analyses
Published in Journal of Nuclear Science and Technology, 2023
Mohammad Allaf, Koji Okamoto, Nejdet Erkan
ADNS’ principle is to have a beam of accelerated particles impact on a target of non-fissile material and release neutrons by processes other than fission. Spallation is the prominent process; which is achieved by a high-energy (order of GeV) proton beam directed at a heavy target (e.g. tungsten, tantalum, depleted uranium, lead, etc.) expels a number of spallation particles including neutrons (e.g. SNS [13]). The other approach that is implemented using accelerators is to bombard materials such as lithium or beryllium with low to medium energy protons or deuterons (~2-70 MeV) producing neutrons (e.g. LENS, Indiana Univ [1].).