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Nuclear Fuels, Nuclear Structure, the Mass Defect, and Radioactive Decay
Published in Robert E. Masterson, Introduction to Nuclear Reactor Physics, 2017
The binding energy per nucleon is an important parameter when attempting to understand how stable a particular nucleus can be. Nuclei where the binding energy per nucleon is high are relatively stable, and nuclei where the binding energy per nucleon is low are not as stable. The binding energy per nucleon is about 7.6 MeV for a heavy element like Uranium and about 8.5 MeV for elements of an intermediate atomic weight like Barium and Krypton. Hence, if a U-235 nucleus were to split apart into Barium-141 and Krypton-92 atoms, then we would release about 235 × (8.5 to 7.6 MeV) ≅ 210 MeV of useful energy. (However, only 200 MeV of this is actually recoverable.) Another implication of the nuclear binding energy curve is that some nuclei (particularly heavy ones) can split apart without having to add additional energy to them. This can be quantified in terms of another variable called the critical energy for fission, ECRIT, which was first discussed in Chapter 3. The values of this critical energy for common isotopes of Thorium, Uranium, and Plutonium are shown in Table 6.9. If one of these nuclei happens to absorb a slow moving neutron, a compound nucleus will be formed with energy equal to the kinetic energy of the incident neutron plus the binding energy of the neutron in the compound nucleus. If the binding energy alone is greater than the critical energy for fission, ECRIT, then the compound nucleus will split apart even when it absorbs neutrons with essentially no kinetic energy.
Elements, Isotopes, and Their Properties
Published in Robert E. Masterson, Nuclear Engineering Fundamentals, 2017
The binding energy per nucleon is an important parameter when attempting to understand how stable a particular nucleus can be. Nuclei where the binding energy per nucleon is high are relatively stable, and nuclei where the binding energy per nucleon is low are not as stable. The binding energy per nucleon is about 7.6 MeV for a heavy element like uranium and about 8.5 MeV for elements of an intermediate atomic weight like barium and krypton. Hence, if a U-235 nucleus were to split apart into Barium-141 and Krypton-92 atoms, then we would release about 235 × (8.5 MeV – 7.6 MeV) ≅ 210 MeV of useful energy. (However, only 200 MeV of this is actually recoverable.) Another implication of the nuclear binding energy curve is that some nuclei (particularly heavy ones) can split apart without having to add additional energy to them. This can be quantified in terms of another variable called the critical energy for fission, ECRIT, which was first discussed in Chapter 3. The values of this critical energy for common isotopes of thorium, uranium, and plutonium are shown in Table 9.9. If one of these nuclei happens to absorb a slow moving neutron, a compound nucleus will be formed with an energy equal to the kinetic energy of the incident neutron plus the binding energy of the neutron in the compound nucleus. If the binding energy alone is greater than the critical energy for fission, ECRIT, then the compound nucleus will split apart even when it absorbs neutrons with essentially no kinetic energy.
Nuclear Energy
Published in Efstathios E. Michaelides, Energy, the Environment, and Sustainability, 2018
Oftentimes, the daughter nucleus is unstable and transforms to another daughter nucleus. Thus, a parent nucleus may cause a series of transformations called a radioactive decay series. Such decay series are typical of the transuranium radioactive elements, with Z > 92 that produce a long series of daughter, mostly radioactive, elements. The last element in this radioactive decay series is usually lead-206 or another stable isotope. The series of nuclear reactions in Equation 5.12 shows the radioactive decay of uranium-238 as a series of alpha and beta decay processes, which involve the several intermediate isotopes of thorium (Th), protactinium (Pa), radium (Ra), radon (Rn), polonium (Po), and bismuth (Bi):
Modeling and optimization for adsorption of thorium (IV) ions using nano Gd:ZnO: application of response surface methodology (RSM) and artificial neural network (ANN)
Published in Inorganic and Nano-Metal Chemistry, 2022
Thorium is the second member of the actinides section of the periodic table and was discovered by Jöns Jacob Berzelius in 1828. It constitutes approximately 0.0007% of the earth's crust. This element is included in the structure of approximately 60 minerals and is not found in free form in nature like uranium. Structurally, it is mostly used by being produced in Taurite Monazite mineral. There are twenty-seven unstable isotopes of thorium (212-237Th) in nature, and there are only 232Th in nature.[28] It has the longest half-life of any natural isotope that begins with the emission of radioactive 232Th alpha particles and stabilizes at 208Pb by emitting beta and gamma rays. This element is three or four times more abundant than uranium in the earth's crust. It is used in increasing the resistance of magnesium in alloys at high temperatures, coating tungsten filaments in lighting, electronic devices, high-quality camera lenses, making high-temperature resistant crucibles, and in nuclear technology and laboratories. As an element with a low toxic effect, radioactive minerals such as uranium and thorium pose a radioactive risk with rays such as alpha, beta, and gamma as a product of the fragmentation of the atomic nucleus.[29]