Nuclear Engineering Fundamentals

A Practical Perspective

Robert E. Masterson

• Editore: CRC Press
• Anno: 2017
• ISBN:
  9781482221510
• Edizione: 1
• Argomento: Physical Sciences
• Categoria: Energy

NUCLEAR ENGINEERING FUNDAMENTALS is the most modern, up-to-date, and reader friendly nuclear engineering textbook on the market today. It provides a thoroughly modern alternative to classical nuclear engineering textbooks that have not been updated over the last 20 years. Printed in full color, it conveys a sense of awe and wonder to anyone interested in the field of nuclear energy. It discusses nuclear reactor design, nuclear fuel cycles, reactor thermal-hydraulics, reactor operation, reactor safety, radiation detection and protection, and the interaction of radiation with matter. It presents an in-depth introduction to the science of nuclear power, nuclear energy production, the nuclear chain reaction, nuclear cross sections, radioactivity, and radiation transport. All major types of reactors are introduced and discussed, and the role of internet tools in their analysis and design is explored. Reactor safety and reactor containment systems are explored as well.

To convey the evolution of nuclear science and engineering, historical figures and their contributions to evolution of the nuclear power industry are explored. Numerous examples are provided throughout the text, and are brought to life through life-like portraits, photographs, and colorful illustrations. The text follows a well-structured pedagogical approach, and provides a wide range of student learning features not available in other textbooks including useful equations, numerous worked examples, and lists of key web resources. As a bonus, a complete Solutions Manual and.PDF slides of all figures are available to qualified instructors who adopt the text. More than any other fundamentals book in a generation, it is student-friendly, and truly impressive in its design and its scope. It can be used for a one semester, a two semester, or a three semester course in the fundamentals of nuclear power. It can also serve as a great reference book for practicing nuclear scientists and engineers. To date, it has achieved the highest overall satisfaction of any mainstream nuclear engineering textbook available on the market today.

1

Understanding the Atom and the Nucleus

1.1 The Nuclear World and the Nuclear Power Industry

In this chapter, we would like to discuss the atomic world upon which the nuclear power industry is based. Compared to the physical world that we live in every day, the nuclear world is far stranger and it can even be considered to be bizarre. In addition, many of its underlying physical processes are governed by statistical probability distributions rather than deterministic Newtonian laws. In many cases, the outcome of a particular reaction follows a statistical probability distribution that can be derived from the Schrödinger wave equation. In the following sections, we would like to present a brief glimpse into what this nuclear world looks like and how the underlying “plumbing” works. If you have never taken a course in nuclear physics before, you will find what we have to say to be strange and even counterintuitive. Nevertheless, the entire nuclear power industry is based on the rules of this subatomic world, and so we would like to describe the inner workings of this world for you now. In future chapters, we will then apply some of these rules to illustrate how they can affect the behavior of a nuclear power plant. In general, nuclear engineering requires a much deeper understanding of the underlying physical processes than other energy sources do.

1.2 Atom and Its Structure

As everyone knows, an atom consists of primarily of empty space. In fact, over 99.999% of the volume of an atom contains nothing at all. This means that the atom is essentially hollow, with the exception of the atomic nucleus, which we will subsequently discuss. Nuclear particles inside of the atom exist within a 3D space that has come to be known as the vacuum. In classical mechanics, the vacuum is “empty” but in quantum mechanics, it is not. Within the vacuum, the laws governing the behavior of the nuclear world are written at an incredibly small distance scale called the Planck scale, which was named for the German physicist Max Planck. The Planck scale corresponds to a distance of about 1.6 × 10⁻³⁷ cm and an energy of about 1.2 × 10¹⁹ GeV. At these distance and energy scales, space itself begins to twist and turn and quantum mechanics and quantum gravity merge. Their rate of convergence is determined by Planck’s constant h, which has a value of h = 6.626 × 10⁻³⁴ kg m²/s in the SI unit system. This fundamental constant of nature is named in honor of Max Planck, whose picture is shown in Figure 1.1b. Planck’s constant is a key component of the Heisenberg uncertainty principle, which will be discussed later in this chapter.

Scientists believe that space at the Planck scale can be described by a seething sea of virtual black holes or multidimensional manifolds (called Calabi–Yau manifolds) that determine the statistical probability distributions that the particles in nuclear reactors obey. Many Nobel Prize winners even believe that our 3D universe is sitting on a “brane” which is contained within a higher dimensional universe in which the force of gravity is stronger than it is in ours. The theory of strings, which is the most complete theory of physical reality ever developed, is based in part on these and other innovative ideas. In the next few chapters, we would like to illustrate how these concepts can be used to design and build a nuclear power plant. Normally, classical nuclear engineering is not approached in this way.

To begin our discussion, consider for the moment a typical atom and the “empty” space it contains. We will start with a very simple view of the atom and then expand upon it. To give you an idea of how much space exists in an atom, suppose that we do a thought experiment where we are able to expand the atom to the size of a modern football stadium and the parking lot around it (which is typically about 500 yards or half of a kilometer in diameter). In this case, the nucleus of the atom would be about the size of a “pea” located at the 50 yard line and about 99.999% of the mass of an atom would be found inside of this “pea.” This implies that the average atom has a diameter of about 1 × 10⁻⁸ cm, and this diameter is defined as the distance from one side of the electron cloud to the other. The nucleus inside of the electron cloud has an average diameter of about 1 × 10⁻¹² cm, which is about 10,000 times smaller. The volume of the nucleus is therefore (104)3=1012 times less than that of the atom as a whole. Hydrogen, which is the smallest atom, has an electron cloud with a diameter of about 0.25 × 10⁻⁸ cm, while larger atoms like cesium (Cs) have an electron cloud with a diameter of about 1.6 × 10⁻⁸ cm. Hence, the electron clouds can vary in diameter by a factor of about 8, and their total volume can vary by a factor of about 500(V ∝ D). The diameters of the electron clouds for most atoms tend to fall somewhere between these two extremes (see Figure 1.2). However, because of the orbital configurations of the electrons, heavier atoms do not always have larger electron clouds than lighter atoms do. In particular, notice that the uranium atom, which is the heaviest naturally occurring element, has a smaller electron cloud than the cesium atom does. Exercise 1.1 shows how the diameters of these two electron clouds compare. In reality, the electron “cloud” surrounding the nucleus is not a well-defined structure, and the surface of the nucleus of the atom is also not a well-defined surface. In fact, it tends to oscillate like a drop of incompressible fluid. This undulation can be described by the liquid drop model of nuclear structure, which is discussed in great detail in Chapter 9. The various orbital configurations of the electrons are also described there.

FIGURE 1.1 (a) Two pictures of the Dallas Cowboys Football Stadium in which the Super Bowl is sometimes played. If an atom were the size of this football stadium, the nucleus would be the size of a “pea” on the 50 yard line. (b) The Planck scale, named after Max Planck on the right, is an incredibly small distance scale in ordinary space where the laws of atomic and nuclear structure are written. Superficially, the vacuum appears to be just empty space, but upon closer inspection, virtual particles pop into and out of existence in the vacuum all of the time. The amount of time that they can be seen before they vanish again is determined by the Heisenberg uncertainty principle, which is discussed later in the chapter. The lower the energy of a virtual particle, the longer it will stay in our world before it disappears into the vacuum again. The image on the left is a simulation of a quantum field theory ­calculation showing how virtual particles form and disappear in the vacuum. The mathematics describing this behavior was ­developed by Richard Feynman and others about 50 years ago. The theory of strings, which we have discussed in the later part of this chapter, was then built on this theoretical foundation. (From medium.com with a special credit to Derek Leinweber.)

FIGURE 1.2 The sizes of some common atoms, as measured by the diameter of the electron cloud. The values shown are in picometers (pm) and have an accuracy of about 5 pm. The shade of the boxes ranges from red to yellow as the radius increases; gray indicates a lack of data. Here, 1 pm = 1.0 × 10⁻¹⁰ cm. (Adapted from Wikipedia and an article published by J.C. Slater in 1964.)

1.3 Nuclear Energy Production

The entire nuclear power industry is based on the fact that it is possible to access and m...