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This chapter presents the physics behind a variety of particle accelerators, which are used in nuclear physics research and other applications. A brief review of the effects of electric and magnetic fields on charged particles is provided. Early approaches were the high-voltage machines such as the Van de Graaff electrostatic generator and the Cockroft-Walton voltage multiplier. The linear accelerator (LINAC) utilizes successive particle accelerations through a series of tubular electrodes. By employing a magnetic field, the cyclotron accelerates particles in a circular direction. Within the betatron, a changing magnetic field produces an electric field that accelerates electrons to relativistic speeds; whereas in the synchrotron, both radiofrequency and time-varying magnetic fields are used.

This chapter faces the realization that the same atoms that can produce life-saving electricity can also be used to construct weapons of mass destruction. Some facilities, such as enrichment and reprocessing, in the nuclear fuel cycle can also serve dual uses when considering proliferation. The original atomic bombs were constructed of highly enriched uranium and high-grade plutonium, but their development led to thermonuclear devices with much larger yields. Thus far, nuclear war has been avoided by policies such as mutual assured destruction and international agreements such as the Non-Proliferation Treaty. The International Atomic Energy Agency (IAEA) is charged with performing worldwide nuclear material safeguards inspections. The legacy of the nuclear weapons arms race has left considerable weapons-grade materials that must be dealt with.

Research by Gast and Bournia on nuclear reactor cores in the form of elliptical cylinders is revisited. Derivations are presented, and data are extended in scope and accuracy. Findings on asymptotic series for constants needed in the evaluation of Mathieu functions are reported, along with accurate alternative techniques. Geometric bucklings are expressed in terms of circular cylinders with equivalent surface-to-volume ratios in a form that allows easy interpolation from tables. The estimation of extrapolation distances at boundaries of elliptical systems is addressed. Applications considered include a possible research reactor, the damage of fuel storage/shipping casks, and decommissioning of the damaged Windscale reactor.

This chapter delves into the engineering approaches to releasing the power of fusion. From a comparison of fusion reactions, the deuterium-tritium reaction is seen as that employed in the first generation of fusion reactors. The Lawson criterion provides density and confinement time requirements for practical fusion reactors. Two fundamental confinement approaches, magnetic and inertial, are being pursued. The international ITER tokamak project appears to have the lead in achieving the demonstration of a fusion reactor system.

This chapter tackles the crucial topic of nuclear safety beginning with the realization that it extends far beyond nuclear power plants. Reactor safety is assured through active, passive, and inherent safety mechanisms. As the basic strategy of reactor safety is the retention of the radioactive material present, the plant systems, including containment isolation and cooling and emergency core cooling, serving such a purpose are explained. The discipline of probabilistic risk assessment is explained by example. A major focus of this chapter is to explain the events that took place at three major nuclear reactor accidents, specifically, Three Mile Island, Chernobyl, and Fukushima. After discussing the concept of risk, the nuclear security is briefly considered.

This chapter concentrates on the final disposition of radioactive materials. After explaining the difference between open and closed nuclear fuel cycles, the categories of nuclear waste, such as high and low level, are defined. Spent reactor fuel is stored in pools, generally near the reactor, until sufficient thermal and radioactive cooling occurs. Transportation is regulated by the federal government, and stringent testing is performed on canisters that carry nuclear materials. Although not commercially permitted in the United States, nuclear fuel reprocessing separates radioactive waste from the remaining fissionable materials that can be re-used in a reactor. In the U.S. political issues have delayed the completion of a geologic repository for high-level waste disposal. Low-level wastes are generated by a variety of facilities including universities and hospitals. The nuclear weapons race had a significant negative impact on the environment at those defense sites involved. Several methods have been approved for nuclear power plant decommissioning.

This chapter elucidates the means by which ionizing radiation is detected and measured. Instrument performance is quantified by specifications such as efficiency, dead time, and energy resolution. The gas counters consist of ionization chambers, proportional counters, and the Geiger-Mueller detector. Neutrons are detected by selecting reactions appropriate to the neutron energy within sensors such as fission chambers and He-3 probes. Specialized scintillator materials emit a flash of light when particular ionizing radiations strike the material. Thermoluminescent materials are commonly used in personnel dosimetry. Spectroscopy applications for radionuclide identification and quantification typically employ solid-state detectors. The probabilistic nature of radioactive decay requires applying statistics in radiation counting. Radiation detectors are deployed to assist in intercepting illicit nuclear material shipments and diversions.

The solution of the point-kinetics equations with a neutron source can be expressed in terms of the solution without a source by a simple scaling involving reactivities, with an added constant term. Proof is provided by both the Laplace transform and matrix methods

Publisher Summary Compliance with licensing rules plays an important role in the operation of any nuclear facility. A number of other organizations have evolved to provide technical information, develop standards, protect against diversion of nuclear materials, improve nuclear power operations, and perform private research and development. This chapter discusses the Atomic Energy Acts. The first law in the U.S. dealing with control of nuclear energy was the Atomic Energy Act of 1946. Issues of the times were involvement of the military, security of information, and freedom of scientists to do research. The federal government through the Nuclear Regulatory Commission (NRC) has the authority to license and regulate nuclear facilities of all types, from a multireactor power station down to isotope research in an individual laboratory. The Office of Nuclear Reactor Regulation of the NRC requires applicants for a reactor license to submit a detailed safety analysis report and an environmental report. These documents provide the basis for issuance of a construction permit, and later when the plant is completed, an operating license. The process involves several steps. Once a plant is licensed, the Office of Inspection and Enforcement has oversight. The nuclear operations are subject to continual scrutiny by the resident inspector and periodic inspection by teams from the regional NRC office. Training of operating personnel goes on continuously, with one shift in training while the other shifts running the plant. The chapter also discusses The Energy Policy Act of 1992, which provides comprehensive national goals and requirements on energy efficiency and generation.

Publisher Summary A device that permits the controlled release of fusion energy is designated as a fusion reactor in contrast with one yielding fission energy—the fission reactor. This chapter discusses fusion reactors and presents a comparison of fusion reactions. The potentially available energy from the fusion process is enormous. The possibility of achieving controlled thermonuclear power on a practical basis has not yet been demonstrated, but progress in recent years gives encouragement that fusion reactors can be in operation soon. The chapter reviews choices of nuclear reaction, discusses the requirements for feasibility and practicality, and describes the physical features of machines that have been tested. The development of fusion as a new energy source involves several levels of accomplishment. The first is the performance of laboratory experiments to show that the process works on the scale of individual particles and to make measurements of cross sections and yields. The second is to test various devices and systems intended to achieve an energy output that is at least as large as the input and to understand the scientific basis of the processes. The third is to build and operate a machine that will produce net power of the order of megawatts. The fourth is to refine the design and construction to make the power source economically competitive. The chapter gives an overview of the many complex machines devised to generate a plasma and to provide the necessary electric and magnetic fields to achieve confinement of the discharge.

Publisher Summary This chapter provides answers to questions that are related to energy economics. These questions include the comparative costs of electricity from nuclear plants and from coal or oil plants, the expected use for nuclear power in the future, and the choices of nuclear power research and development that must be made. Economics is the study of how societies use scarce resources to produce valuable commodities and distribute them among different people. Half the cost of electric power is for generation. Electricity from plants that use coal or nuclear fuel is comparable in cost, with a tradeoff between capital costs and fuel costs. Costs of construction of nuclear plants and the time to complete them in the United States were exorbitant for several reasons. There have been no orders for new nuclear plants since 1978. The nuclear industry has several opportunities for improvements including license extension but is faced with the challenges of electricity restructuring. Several advanced reactor concepts are being promoted to preserve the nuclear option. A nuclear renaissance involves building additional power plants and carrying out research on new reactor concepts.

Nuclear reactors may be classified by purpose or use, key components, method of heat extraction, power level or neutron flux, or arrangement of component materials. Commercial reactors are also classified by the companies involved in design and building of the facility. Reactors used for power generation, either heat or electrical, propulsion, whether naval vessels or spacecraft, radioisotope production, materials testing, basic research, and training are discussed. The development of nuclear reactors is presented, including information gleaned from the two principal nuclear accidents of the 1980s. The pressurized lightwater reactor is the most common power generation reactor in the United States, but the boiling water reactor is also used. In Canada, heavy-water reactors are usually employed. These and other reactors, such as the molten salt and the fast breeder reactor, are described. Keywords: Reactor components; Nuclear reactors; Alternative heat sources; Research reactors; Classification; Graphite reactors; High temperature gas-cooled reactors; Chernobyl; Hanford N reactor; Pressurized water; Boiling water; Heavy water; CANDU reactors; training; Savannah River; Fast breeder reactors; Aqueous reactors; Aircraft reactors; Naval reactors; Maritime reactors; Space reactors

Publisher Summary Radiation in the form of gamma rays, beta particles, and neutrons is being used in science and industry to achieve desirable changes. Radiation doses control offending organisms, including cancer cells and harmful bacteria, and sterilizes insects. Local energy deposition can also stimulate chemical reactions and modify the structure of plastics and semiconductors. Neutrons and X-rays are used to investigate basic physical and biological processes. This chapter describes some of these important applications of radiation. Diseases such as cancer can be treated by gamma rays. Food spoilage is reduced greatly by irradiation. Medical supplies are rendered sterile within plastic containers. Sewage sludge can be disinfected by irradiation. New and improved crops are produced by radiation mutations. The sterile insect technique has controlled insect pests in many areas of the world. Radiation serves as a catalyst in the production of certain chemicals. Properties of fibers and wood are enhanced by radiation treatment. Desirable impurities can be induced in semiconductor materials by neutron bombardment. The scattering by neutrons provides information on magnetic materials, and interference of neutron beams is used to examine surfaces. Scattered neutrons yield estimations of location and size of minute biological structures. Synchrotron X-rays are required for detailed study of biological molecules.

Nuclear reactors for dual use in training and research were established at about 50 universities in the period since 1950, with assistance by the U. S. Atomic Energy Commission and the National Science Foundation. Most of the reactors are in active use for a variety of educational functions--laboratory teaching of undergraduates and graduate students, graduate research, orientation of visitors, and nuclear power plant reactor operator training, along with service to the technical community. As expected, the higher power reactors enjoy a larger average weekly use. Among special programs are reactor sharing and high- school teachers' workshops. (auth)

This chapter focuses on neutron chain reactions. The possibility of a chain reaction involving neutrons and a nuclear fuel such as uranium is dependent on the number of neutrons produced per absorption, η . Its value must be more than one because of inevitable losses of neutrons. However, to achieve a self-sustaining chain reaction, one in which no neutrons need to be supplied, a certain amount of uranium must be brought together, the “critical” mass. The power developed by a reactor is a quantity of great interest for practical reasons. Power is related to the neutron population, and also to the mass of fissile material present. In a reactor, it is necessary to add fuel very infrequently because of the very large energy yield per pound, and the fuel content remains essentially constant. The presence of large amounts of neutron-moderating material such as water in a reactor greatly changes the neutron distribution in energy. Fast neutrons slow down by means of collisions with light nuclei, with the result that most of the fissions are produced by low-energy (thermal) neutrons. Such a system is called a “thermal” reactor in contrast with a system without moderator, a “fast” reactor, operating principally with fast neutrons.

Publisher Summary This chapter describes several methods by which isotopes of uranium and other elements are separated. It presents the calculations on the amount of material that must be processed to obtain nuclear fuel. It also provides estimates of costs. Four methods that depend on differences in mass number are ion motion in a magnetic field, diffusion of particles through a membrane, motion with centrifugal force, and atomic response to a laser beam. The separation of isotopes requires a physical process that depends on mass. In the electromagnetic method, as used in a mass spectrograph, ions to be separated travel in circles of different radii. In the gaseous diffusion process, light molecules of a gas diffuse through a membrane more readily than do heavy molecules. The amount of enrichment in gaseous diffusion depends on the square root of the ratio of the masses and is small per stage, requiring a large number of stages. By the use of material balance equations, the amount of feed can be computed, and by the use of tables of separative work, costs of enriching uranium for reactor fuel can be found. An alternative separation device is the gas centrifuge, in which gases diffuse against the centrifugal forces produced by high speeds of rotation. Laser isotope separation involves the selective excitation of uranium atoms by lasers to produce chemical reactions. Several methods of separating deuterium from ordinary hydrogen are available.

Publisher Summary A device that provides forces on charged particles by some combination of electric and magnetic fields and brings the ions to high speed and kinetic energy is called an accelerator. Many types have been developed for the study of nuclear reactions and basic nuclear structure, with an ever-increasing demand for higher particle energy. This chapter reviews the nature of the forces on charges and describes the arrangement and principle of operation of several important kinds of particle accelerators. Charged particles such as electrons and ions of light elements are brought to high speed and energy by particle accelerators, which employ electric and magnetic fields in various ways. In the high-voltage machines, a beam of ions is accelerated directly through a large potential difference, produced by special voltage multiplier circuits or by carrying charge to a positive electrode. In the linear accelerator, ions are given successive accelerations in gaps between tubes lined up in a row. In the cyclotron, the ions are similarly accelerated but move in circular orbits because of the applied magnetic field. In the betatron, a changing magnetic field produces an electric field that accelerates electrons to relativistic speeds. In the synchrotron, both radiofrequency and time-varying magnetic field are used. High-energy nuclear physics research is carried out through the use of such accelerators. Through several nuclear processes, high-energy charged particles can produce large numbers of neutrons, which can create new fissile materials for use as fuels.

This chapter focuses on nuclear reactor concepts. Although the only requirement for a neutron chain reaction is a sufficient amount of a fissionable element, many combinations of materials and arrangements can be used to construct an operable nuclear reactor. Several different types or concepts have been devised and tested over the period since 1942, when the first reactor started operation, just as various kinds of engines have been used—steam, internal combustion, reciprocating, rotary, and jet. The majority of reactors in operation or under construction have as purpose the generation of large blocks of commercial electric power. Others serve training or radiation research needs, and many provide propulsion power for submarines. Also available are tested reactors for commercial surface ships and for spacecraft. In most modern reactors, the fuel is isolated from the coolant in what is called a heterogeneous arrangement. The alternative is a homogeneous mixture of fuel and moderator or fuel and moderator-coolant.