Introduction to Nuclear Reactor Physics

Robert E. Masterson

• Editore: CRC Press
• Anno: 2017
• ISBN:
  9781498751506
• Edizione: 1
• Argomento: Physical Sciences
• Categoria: Energy

INTRODUCTION TO NUCLEAR REACTOR PHYSICS is the most comprehensive, modern and readable textbook for this course/module. It explains reactors, fuel cycles, radioisotopes, radioactive materials, design, and operation. Chain reaction and fission reactor concepts are presented, plus advanced coverage including neutron diffusion theory. The diffusion equation, Fisk's Law, and steady state/time-dependent reactor behavior. Numerical and analytical solutions are also covered. The text has full color illustrations throughout, and a wide range of student learning features.

1

Nuclear Power in the World Today

1.1Popular Types of Reactors and Their Design Characteristics

Five basic types of nuclear power plants can be commonly found in the world today. These reactors use different combinations of coolants and different types of fuel (usually isotopes of uranium and plutonium) to generate the power the world needs. The ability of a reactor to produce electric power over long periods of time is dependent upon the type of coolant, the composition of the core, and the enrichment of the fuel. All reactors must be able to produce more neutrons than they consume for the fission chain reaction to be sustainable. We will have more to say about this in future chapters of the book. Control rods are then used to absorb these excess neutrons and keep the chain reaction under control. On a high level, it is possible to characterize the commercial nuclear reactors in the world today into five broad categories:

1. Pressurized water reactors (PWRs)
2. Boiling water reactors (BWRs)
3. Heavy water reactors (HWRs)
4. Gas-cooled reactors (GCRs)
5. Liquid metal fast breeder reactors (LMFBRs)

PWRs and BWRs use light water (i.e., ordinary water) to cool the core, while HWRs, like the CANada Deuterium Uranium (or CANDU) reactor, use heavy water as the moderator and the coolant.

Heavy water absorbs fewer neutrons than light water does, and because of this, reactors that are cooled with heavy water do not need enriched uranium to be able to operate successfully. However, they can also use enriched uranium if the need arises. All commercial nuclear power plants have a certain number of design features in common, including the need for fuel rods, control rods, and some type of liquid or gaseous coolant to cool the core. With the exception of GCRs (such as the AGR and the HTGR), which can sometimes use the Brayton thermal cycle to produce power, all other reactors use the Rankine thermal cycle to generate steam that is sent to the power turbines. PWRs, HWRs, and LMFBRs have two coolant loops (a primary and a secondary loop), while BWRs and GCRs have only one. As we discussed in our companion book,* many LMFBRs have a third coolant loop (sometimes called an intermediate loop) to isolate the coolant in the core from the steam generators. This prevents the liquid sodium in the core from interacting with the water in the Nuclear Steam Supply System (or NSSS) and introducing radioactivity into the steam that drives the power turbines. This reduces the chance that any radioactive materials will be released into the environment.

1.2Number of Power Reactors in the World Today

The number of power reactors in the world has increased steadily since the 1950s. Figure 1.1 shows how the number of power reactors has changed between the time that they were first introduced and the present day. Today there are approximately 436 nuclear power plants in operation in 31 countries (see Figure 1.2), and in some countries, they are responsible for generating a large fraction of the total electrical demand. These nuclear power plants are usually implemented using a base-loading model, since the cost of the fuel is a very small part of the cost of power production. The current generation of commercial nuclear power plants has a total electrical output of about 374 GW, and there are an additional 65 power plants under construction in China, India, and Russia with a projected capacity of about 65 GW (see Table 1.1). The number of new reactors under construction is shown in Figure 1.3.

FIGURE 1.1 The number of nuclear power plants operating in the world as a function of time. (Based on data provided by The World Nuclear Association.)

FIGURE 1.2 The number of nuclear reactors in operation, worldwide—by country. (Courtesy of the IAEA. Date: January 2013.)

TABLE 1.1
Number of Nuclear Power Plants in the World Today (Either in Operation or Under Construction)

FIGURE 1.3 The number of nuclear reactors under construction, worldwide—by country. (Courtesy of the IAEA. Date: January 2013.)

By far the most common type of commercial nuclear reactor in the world today is the PWR, which is manufactured and designed by Westinghouse, AREVA, and a number of other vendors. Table 1.2 shows the breakdown of the current-installed base by reactor type. Notice that PWRs represent about 2/3 of the world’s nuclear generating capacity. BWRs, which are manufactured and designed by the General Electric Company (GE), are the next most common type of reactor in the world. They account for about 1/4 of the current installed base. (Other reactors such as fast and gas reactors are then responsible for the remainder.) The percentage of electrical power generated in each country by nuclear power plants is shown in Figure 1.4. Notice that nuclear power generates about 20% of the total electrical power in the United States, while it generates almost 80% of the electrical power in France. Countries that do not hav...