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Safety issues in the siting of nuclear power plants
Published in Peter R. Mounfield, World Nuclear Power, 2017
The two major biological hazards associated with core meltdown and attendant fission product release are (i) direct radiation and (ii) inhalation and ingestion of radioactive material. Protection against radiation can be accomplished by providing sufficient distance between the reactor and the surrounding population, by providing an adequately engineered concrete biological shield or by both of these together. Figure 10.1 shows the effect of distance on direct radiation, and this diagram demonstrates that the dose rate at a given distance is approximately in inverse proportion to the square of the distance. The diagram also shows that a foot (30 cm) thickness of concrete shielding reduces the intensity of direct radiation at any point by about a factor of five which, in turn, approximately halves the distance to population that would be required if no shielding were provided.
Nuclear Hydrogen
Published in Michael Frank Hordeski, Alternative Fuels—The Future of Hydrogen, 2020
It is highly unlikely that a nuclear fission power plant would ever explode like a nuclear bomb, but a loss of coolant accident could result in a melt down condition. In a meltdown, a large amount of radiation could be released at ground level. A nuclear, conventional chemical, or steam explosion could disperse much of the radioactive particles into the atmosphere. This is essentially what happened when the Chernobyl accident occurred in the Soviet Union on April 26, 1986.
Simulation of the Melting Behavior of the UO2-Zircaloy Fuel Cladding System by Laser Heating
Published in Nuclear Science and Engineering, 2023
L. Soldi, D. Manara, D. Bottomley, D. Robba, L. Luzzi, R. J. M. Konings
Typically, a nuclear fission reactor accident is considered to be “severe” when total or partial core meltdown happens.3–6 In these conditions, the average temperature inside the fuel pellet increases hundreds of kelvins higher than the nominal operational values. Such temperature rise may lead to local melting of the fuel, especially in the proximity of the cladding (typically made of a zirconium alloy called Zircaloy, or stainless steel). Here, lower-melting eutectics form due to the chemical interaction between fuel and cladding during normal operations and may potentially lead to liquefaction of the nuclear core. During a nuclear accident in a light water reactor (LWR), the interaction between UO2 fuel and Zircaloy starts well below the cladding melting point (2120 K), at temperatures much lower than the actual fuel liquefaction temperature (3130 K). A U-O-Zr–rich molten material can then be formed at the UO2-Zy interface, which may lead to partial/total dissolution of the fuel.5,6 The composition of this liquid phase significantly depends on the accident scenario and changes with the progression of the accident.