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Reactor Heat Transfer
Published in G. Vaidyanathan, Dynamic Simulation of Sodium Cooled Fast Reactors, 2023
When a nuclear fission takes place, several fission products are formed. Also, neutrons, alpha, beta, and gamma rays are emitted. Most of the heat generated is instantaneously absorbed by the fuel and, to a lesser extent, in the coolant and structural material. The fission fragments are unstable (have excess neutrons) and undergo several transitions by beta emissions before reaching stability. Each of these processes results in heat generation, and this heat must be removed. Depending on the history of the core—i.e., duration of power production, power level, and isotopic content of fuel—the decay heat can be as much as 6–8% of the power at which the reactor operated before shutdown. Figure 3.7 shows the fission product decay heat vs. time curve for a typical fast reactor after shutdown. Decay heat data for all nuclides are available through data files such as evaluated nuclear data file (ENDF/BIV) available from Brookhaven National Laboratory (Rose and Burrows, 1976).
Policy Deployment and QFD: The Twin-Engines of Macrologistics
Published in Martin Stein, Frank Voehl, SM Management, 2020
FPL’s nuclear plants use the fission of uranium to produce electricity. The fission products are radioactive and as they decay, they produce high energy radiation. Excessive exposure to this type of radiation can be harmful to the employees and to the public. Logistics management plays a key role in improving the safety factor in this environment. This led to the Prime Nuclear Safety Function. According to John Hudiburg: “The ability of our nuclear plants at Turkey Point and St. Lucie to produce power depends upon the strictest conformance to NRC regulations. If FPL or the NRC identifies a condition considered adverse to safety, the unit will be shut down until the condition is remedied. The NRC may suspend or revoke our license to operate, as they have five other utility units at the present time.”
Other civil applications of nuclear energy
Published in Kenneth Jay, Nuclear Power, 2019
In this last section we shall discuss briefly the uses of radiation in industrial processes. These uses are not likely to require the development of special reactors; they are important to nuclear energy industry mainly because they offer a way by which some of the fission products, often regarded as nuclear waste, may be disposed of with profit. The quantities of fission products extracted from used fuel in a large-scale industry will be enormous; it has been estimated that the stations of the British power programme will, by 1966, be yielding fission products whose total radioactivity will amount to three thousand million curies a year, that is to say, will be equivalent in radioactivity to three thousand million grams of radium. To set the scale of this amount, the total quantity of radium in use throughout the world before the war was about a ten-millionth of this. The greater part of the fission products, some 90 per cent, have short half-lives and their radioactivity decays to innocuous levels after they have been stored for a few years. The half-lives of the remaining 10 per cent, however, are much longer, so that their radioactivity remains at a high level for centuries. There will thus be the problem of storing indefinitely hundreds of millions of curies of fission products each year, unless some use can be found for them.
Adsorption properties of radionuclides on BC3: the first principles study
Published in Molecular Physics, 2022
Nan Zhou, Yong Qin, Jie Tan, Jinjuan Cheng, Shuaixing He, Hai Li, Xijun Wu
With today's scarcity of resources, developing new energy sources such as nuclear power is critical. Nuclear energy development will result in a substantial number of radionuclides. The principal nuclear fission products are cesium, strontium, cobalt, and silver, which are typically found in radioactive effluent from nuclear power plants, spent fuel reprocessing, radionuclide manufacturing facilities, and other sources. They represent a significant threat to human health and the ecology, hence removing radionuclides is critical. So far, various separation techniques have been developed successively, such as chemical precipitation, biological treatment, ion exchange, electrodialysis, membrane separation, evaporation, solvent extraction, and adsorption [1]. Among these methods, adsorption is of great interest because of its simple operation, low cost and low energy consumption. Separation techniques based on physical adsorption using porous materials are a cost-effective alternative to expensive cryogenic distillation [2].
Bifurcation Analysis of Xenon Oscillations in Large Pressurized Heavy Water Reactors with Spatial Control
Published in Nuclear Science and Engineering, 2022
Abhishek Chakraborty, Suneet Singh, M. P. S. Fernando
The safe operation of nuclear reactors is one of the most challenging aspects of the nuclear power industry. It involves a number of processes involving the generation of neutrons, their specific multiplications, their control, and the extraction of useful power out of the heat energy generated in the process. In most of the operating nuclear reactors, energy is produced by chain nuclear fission of 235U. In nuclear fission, a large nucleus like 235U is broken into multiple nuclei (fission products) with release of ~200 MeV of energy on absorption of a thermal/fast neutron(s). The heat which is produced in fission has to be removed by a coolant (generally H2O, D2O for thermal reactors and Na, Pb for fast reactors). This demands an efficient coupling between the neutronics and the thermal hydraulics to ensure a smooth, streamlined generation of power.
Reactor Physics Analysis Assessment of Feasibility of Using Advanced, Nonconventional Fuels in a Pressure Tube Heavy Water Reactor to Destroy Long-Lived Fission Products
Published in Nuclear Technology, 2021
The operation of nuclear reactors [including Generation 3+ (Gen-III+), Generation IV (Gen-IV), and Small Modular Reactor (SMR) technologies] produces high-level radioactive waste in the spent fuel, which contains numerous radioactive fission products, minor actinides (such as isotopes of Np, Pu, Am, Cm, and heavier elements). In addition, various radioactive isotopes are created in a nuclear reactor by neutron activation in structural components and in the coolant. Fortunately, many fission products have very short half-lives, ranging from seconds to less than a year, and will decay to relatively insignificant concentrations (similar to the radioactivity and radiotoxicity of natural uranium ore) in less than 10 years. Fission products such as 90Sr (Thalf-life ~ 29 years) and 137Cs (Thalf-life ~ 30 years) must be safely stored for at least 400 years [perhaps in a deep geological repository (DGR)] before they decay to less than 0.01% of their original level. In addition to minor actinides found in used nuclear fuel and the radioactive isotopes found in reactor structural components created by neutron activation, a key long-term problem for radioactive waste storage is the seven main long-lived fission products (LLFPs) listed in Table I, which have half-lives ranging from 100 000 years (for 126Sn) to 15 700 000 years (for 129I).