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Isotope Techniques in Flood Analysis
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Samir Al-Gamal, Saeid Eslamian
Isotopes are the atoms of the same element that have different numbers of neutrons. Differences in the number of neutrons among the various isotopes of an element mean that the various isotopes have the different masses. The superscript number to the left of the element designation is called the mass number and is the sum of the number of protons and neutrons in the isotope (Figure 12.4). For example, among the hydrogen isotopes, deuterium (denoted as D or 2H) has one neutron and one proton. This mass number of 2 is approximately equal to twice the mass of protium (1H), whereas tritium (3H) has two neutrons and its mass is approximately three times the mass of protium. Isotopes of the same element have the same number of protons. For example, oxygen has three stable isotopes,16O, 17O, and 18O; hydrogen has two stable isotopes, 1H and 2H (deuterium), and one radioactive isotope,3H (tritium). All isotopes of oxygen have eight protons; however, an oxygen atom with a mass of 18 (denoted 18O) has two more neutrons than oxygen with a mass of 16 (16O). Isotope names are usually pronounced with the element name first, as in “oxygen-18” instead of “18-oxygen” (Figure 12.4 and Table 12.1) (Hoefs,1997).
Radioactive Materials and Radioactive Decay
Published in Robert E. Masterson, Nuclear Engineering Fundamentals, 2017
In other words, an isotope must have exactly the right combination of protons and neutrons to be stable. If it does not, the forces inside of the nucleus will not be in balance, it will become radioactive, and it must decay until exactly the correct ratio of neutrons to protons is reached. The element oxygen, which has eight protons (Z = 8), can be used to illustrate this point as well. In addition to having eight protons, oxygen has eight known isotopes—13O, 14O, 15O, 16O, 17O, 18O, 19O, and 20O—that have 5, 6, 7, 8, 9, 10, 11, and 12 neutrons, respectively. The first three are unstable (13O, 14O, and 15O (Z = 8, N = 5,6,7)) because they have too few neutrons, and the heaviest two are unstable (19O and 20O (Z = 8, N = 11,12)) because they have too many neutrons. These isotopes correspond to the orange, blue, and yellow dots on each side of the black dots shown in Figure 6.4. Only the middle three isotopes of oxygen are stable—16O, 17O, and 18O (with Z = 8 and N = 8,9,10)—because they have the just right number of neutrons to keep the nucleus in balance. Notice that only the three black dots in the middle (Z = 8 and N = 8,9,10) are physically stable, while the others decay away.
Behaviour and comparison of dissolved silica and oxygen-18 as natural tracers during snowmelt
Published in A. Kranjc, Tracer Hydrology 97, 2020
A.C. Hildebrand, M. Lindenlaub, Ch. Leibundgut
During the last decades, hydrograph separation by natural tracers, has become a powerful tool for the study of runoff generation processes. However, by applying this method, the use of stable isotopes is limited to time periods with noticeable differences in isotopic content between system input and pre-event reservoirs. In addition, by the use of isotopes at least three different components can be detected, in respect to the two available isotope tracers oxygen-18 (18O) and deuterium. Consequently, this leads to the need for hydrochemical tracers which do not show the limitations mentioned above.
The importance of groundwater to the upper Columbia River floodplain wetlands
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2023
Casey R. Remmer, Rebecca Rooney, Suzanne Bayley, Catriona Leven
The stable isotopes of oxygen and hydrogen have long been used to characterize water sources and the influence of evapotranspiration in lakes and wetlands (i.e. Blasch and Bryson 2007; Yi et al. 2008; Wassenaar, Athanasopoulos, and Hendry 2011). The stable isotopes approach has proven particularly valuable in understanding the dynamic hydrology of northern floodplains and remote, wetland-dominated landscapes (e.g. Gibson and Edwards 2002; Brock, Wolfe, and Edwards 2007; MacDonald et al. 2017). For example, water stable isotopes were valuable in quantifying the role of input water sources to water bodies in the Peace-Athabasca Delta (Wolfe et al. 2008, Remmer et al. 2020a,2020b), the Slave River Delta (Brock, Wolfe, and Edwards 2008), and the Old Crow Flats (Turner et al. 2014). Additional insights into hydrological processes in dynamic, wetland-rich landscapes are becoming available as researchers combine stable tracers, such as water isotopes, with statistical analyses underlying source-portioning mixing models commonly used for animal diet differentiation (e.g. Wynants et al. 2020; Kay et al. 2021).
Advancing Methods for Fusion Neutronics: An Overview of Workflows and Nuclear Analysis Activities at UKAEA
Published in Fusion Science and Technology, 2023
Alex Valentine, Thomas Berry, Steven Bradnam, Hari Chohan, Tim Eade, Callum Grove, James Hagues, Keir Hearn, James Hodson, Kimberley Lennon, Jonathan Naish, Joseph Neilson, Chantal Nobs, Lee Packer, Andrew Turner, Anthony Turner, Luke Woodall, Ross Worrall
During fusion operations, a significant volume of fluid will pass through in-vessel components, including coolant, and possibly, liquid breeder material. The ITER Test Blanket Module Program is investigating several different blanket concepts seeking to optimize tritium breeding with technological feasibility. Lithium-lead (LiPb) is one example of a liquid metal breeder material in several of the currently explored concepts. Flowing water is used as a coolant in certain blanket concepts, as well as more widely across ITER components to extract excess heat. In the presence of a neutron field, water is activated through (n,p) reactions with isotopes of oxygen, O. The most notable product is N, which decays through emission of 6.13-MeV (I = 67%) and 7.12-MeV (I = 5%) (Ref. 40) photons. There is an additional gamma source term in the fluid that stems from activated corrosion products, along with secondary neutron emission from the decay of N. Other potential coolants in future fusion devices include molten metals and salts, which would introduce different activation and corrosion profiles. The movement of activated fluids through the tokamak complex has significant implications for the demonstration of safety.
Exhaust behavior of tritium from the large helical device in the first deuterium plasma experiment
Published in Journal of Nuclear Science and Technology, 2020
Masahiro Tanaka, Naoyuki Suzuki, Hiromi Kato
Figure 9 shows the relationships between the concentrations of tritiated hydrocarbons, water vapor, and tritiated hydrogen gas. The concentration of tritiated hydrocarbons was proportion to that of tritiated hydrogen gas. It suggested that a part of produced tritium in core plasma slowed down and transported to the divertor region along with the scrape-off layer. Then the divertor plasma contained tritium reacted with the carbon and tritiated hydrocarbons were generated. Also, tritiated hydrocarbons would be generated by hydrogen or deuterium glow discharge operation. On the other hand, the behavior of tritiated water vapor might not seem to be related to that of tritiated hydrogen gas. The source of tritiated water vapor would be from the metal wall because the vacuum vessel contained a small amount of water in the metal wall. Thus, tritiated water vapor was increased during the long-term wall baking operation. Besides, hydrogen isotopes and oxygen on the stainless steel as the first wall would be spluttered and released by the glow discharge operation. Then the tritiated water vapor was generated via the chemical reaction between hydrogen isotope and oxygen during the glow discharge operation. Therefore, the behaviors of tritiated water vapor would be independent of that of tritiated hydrogen gas.