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Issues Facing New Nuclear Build
Published in William J. Nuttall, Nuclear Renaissance, 2022
The process by which the neutrons are slowed down should be familiar to players of table ball games such as billiards, pool, or snooker. The neutron loses kinetic energy via a process of collisions. Most energy is lost if the neutron collides with a particle of similar mass, typically a light atom. The collisions are essentially elastic in that no kinetic energy is absorbed by the particles themselves. All the neutron kinetic energy remains as kinetic energy; it is simply divided between the particles involved in the collision. A neutron colliding with a very heavy atomic nucleus would transfer very little energy to the heavy atom and would simply bounce off with very little deceleration. In nuclear reactors, fast neutron moderation is usually achieved using water (in which hydrogen is the most important component) or using carbon in the form of graphite. Graphite and water are stable enough and sufficiently easily handled to be good engineering materials for nuclear reactor design. Several reactor designs use so-called light water as the moderator (that is water with conventional isotopic hydrogen) whereas others, such as the Canadian CANDU design, use so-called heavy water. Heavy water is water manufactured using deuterium instead of normal isotopic hydrogen. These issues are discussed further in Chapter 6, where various water-cooled reactor designs are discussed in depth.
Physical Methods for Characterizing Solids
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
where λ is the wavelength, p is the momentum of the particles (p = mv, mass × velocity), and h is Planck’s constant. Neutrons are released in atomic fission processes from a uranium target, when they have very high velocities and very small wavelengths. The neutrons generated in a nuclear reactor can be slowed using heavy water. This results in a wavelength of about 0.1 nm (1 Å) therefore making them suitable for structural diffraction experiments. The neutrons generated have a range of wavelengths, and a monochromatic beam is formed using reflection from a plane of a single-crystal monochromator at a fixed angle (according to Bragg’s law). Structural studies need a high flux of neutrons and this usually means that the only appropriate source is a high-flux nuclear reactor such as at Oak Ridge in the United States and Grenoble in France.
Reactor Coolants, Coolant Pumps, and Power Turbines
Published in Robert E. Masterson, Nuclear Reactor Thermal Hydraulics, 2019
The distillation process used to create heavy water has many different stages, and at each stage, the lighter water molecules are separated from the heavier ones by heating them and evaporating the mixture. The lighter molecules are evaporated away, and over time, only the heavy water molecules remain. However, it takes several thousand stages to create a small amount of pure heavy water. The most common process for creating heavy water is the Girdler sulfide process, which is widely used in Canada, Norway, and the United States. As we mentioned earlier, heavy water or D2O has a natural abundance of about one part in 6,420. The rest of the water in the Earth’s oceans, lakes, and rivers is H2O. A vial of heavy water is shown in Figure 19.2. Normally, heavy water is not toxic to human beings. It is chemically similar to ordinary water and looks about the same. Heavy water is about 10% heavier than light water, and its density is 1.10 g/cm3 at 4 °C and 0.99823 gm/cm3 (or 998.23 kg/m3) at 20 °C. The density of ordinary water is 1.00 g/cm3 at 4 °C and 0.99823 gm/cm3 (or 998.23 kg/m3) at 20 °C. Moreover, its thermal–physical properties are almost the same. The boiling point for heavy water is about 1.3°C higher than it is for ordinary water. Thus, heavy water boils at 101.4°C, and light water boils at 100°C. This difference in the boiling point is essential to the success of the heavy water production process.
Tritium Behavior in Water and Gas Produced by a Fully Tritium-Compatible Electrolyzer
Published in Fusion Science and Technology, 2023
Carmen Varlam, Irina Vagner, Ionut Făurescu, Anisia Bornea, Denisa Făurescu, Diana Bogdan
Romanian nuclear electric energy is produced by the Cernavodă nuclear power plant (NPP), with two CANDU reactors, one put in service in 1996 and the other in 2007. The Canadian-designed power reactors use heavy water (deuterium oxide) as a moderator and cooling agent and use natural uranium as the fuel. Tritium is produced continuously mainly in the moderator, and because of the long period of exploitation (one of the units has more than 25 years of operation), heavy water detritiation has become a necessity.
The Current Status of the Heavy Water Detritiation Facility at the NRC (Kurchatov Institute) – PNPI
Published in Fusion Science and Technology, 2020
S. D. Bondarenko, I. A. Alekseev, O. A. Fedorchenko, T. V. Vasyanina
Heavy water is used as a neutron moderator, reflector, and coolant in nuclear power and research thermal reactors. Tritium is produced in heavy water owing to neutron capture by deuterium atoms. The dose of radiation exposure to personnel increases with the rise of tritium content in heavy water. Thus, heavy water reactors require facilities to remove tritium. Tritium removal facilities (TRFs) are under operation in Canada and Korea, and under construction in Romania.1–3