This is known as a nuclear chain reaction. A portion of these neutrons may be absorbed by other fissile atoms and trigger further fission events, which release more neutrons, and so on. The heavy nucleus splits into two or more lighter nuclei, (the fission products), releasing kinetic energy, gamma radiation, and free neutrons. When a large fissile atomic nucleus such as uranium-235 or plutonium-239 absorbs a neutron, it may undergo nuclear fission. As of early 2019, the IAEA reports there are 454 nuclear power reactors and 226 nuclear research reactors in operation around the world. Some reactors are used to produce isotopes for medical and industrial use, or for production of weapons-grade plutonium. Nuclear generated steam in principle can be used for industrial process heat or for district heating. These either drive a ship's propellers or turn electrical generators' shafts. Heat from nuclear fission is passed to a working fluid (water or gas), which in turn runs through steam turbines.
Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion.
The obtained results also show that in the analysis of natural circulation flow in the primary circuit, the reverse flow in the inverted U-tubes of the steam generator must be taken into account.Core of CROCUS, a small nuclear reactor used for research at the EPFL in SwitzerlandĪ nuclear reactor, formerly known as an atomic pile (so-called because the graphite moderator of the first reactor was placed into a tall pile ), is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. This indicates that the developed mathematical model and solution method can be used to correctly predict the reverse flow in the inverted U-tubes of the steam generator with natural circulation. The predicted sharp drop of the fluid temperature in the inlet plenum of the steam generator due to reverse flow agrees very well with the experimental data. Through the calculation, the mass flow rates of normal and reverse flows in individual U-tubes are obtained. The reverse flow in an inverted U-tube steam generator of a simulated pressurized water reactor with natural circulation is analyzed. The mathematical model and numerical calculation method for analyzing the reverse flow in inverted U-tubes of the steam generator with natural circulation have been developed. The mechanism of reverse flow in inverted U-tubes of the steam generator with natural circulation is graphically analyzed by using the full-range characteristic curve of parallel U-tubes.
In this paper, we report on the analysis of reverse flow in inverted U-tubes of a steam generator under natural circulation condition.
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