E-Book, Englisch, 264 Seiten, Format (B × H): 191 mm x 235 mm
Obodovskiy Fundamentals of Radiation and Chemical Safety
1. Auflage 2015
ISBN: 978-0-12-802053-1
Verlag: William Andrew Publishing
Format: EPUB
Kopierschutz: 6 - ePub Watermark
E-Book, Englisch, 264 Seiten, Format (B × H): 191 mm x 235 mm
ISBN: 978-0-12-802053-1
Verlag: William Andrew Publishing
Format: EPUB
Kopierschutz: 6 - ePub Watermark
Fundamentals of Radiation and Chemical Safety covers the effects and mechanisms involved in radiation and chemical exposure on humans. The mechanisms and effects of these damaging factors have many aspects in common, as do their research methodology and the methods used for data processing. In many cases of these types of exposures the same final effect can also be noted: Cancer. Low doses of radiation and small doses of chemical exposure are continuously active and they could influence the entire population. The analysis of these two main source hazards on the lives of the human population. The analysis of these two main source hazards on the lives of the human population is covered here for the first time in a single volume determining and demonstrating their common basis. Fundamentals of Radiation and Chemical Safety includes the necessary knowledge from nuclear physics, chemistry and biology, as well the methods of processing the experimental results. Intended for students, graduate students and professionals in the fields of physics, chemistry, biology, ecology, and a range of interdisciplinary sciences. The book can also be used by practitioners as a reference in order to find more detailed information on special issues of radiation and chemical safety. Tis title focuses on the effects of low radiation dosage and chemical hormesis as well as the hazards associated with, and safety precautions in radiation and chemicals, rather that the more commonly noted safety issues high level emergencies and disasters of this type.
- Brings together, for the first time, the problems of radiation and chemical safety on a common biophysical basis.
- Relates hazards caused by ionizing radiation and chemicals and discusses the common effective mechanisms
- Outlines common methodology and data processing between radiation and regular chemical hazards
- Concerns primarily with low levels of radiation and chemical exposure
Zielgruppe
<p>Chemists, physical chemists, chemical engineers, physicists, biologists and radiation experts and safety officers, governments and radiation protection agents.</p>
Autoren/Hrsg.
Fachgebiete
Weitere Infos & Material
Introduction 1. Basic Nuclear Physics 2. Basic Biology 3. Evaluation of the Action of Hazardous Factors on a Man 4. Effects of Ionizing Radiation on Biological Structures 5. Effects of Chemicals on Biological Structures 6. Radiation and Chemical Hormesis 7. Synergy of Radiation and Chemicals 8. Pharmcological Methods of Defense 9. Control of Radiation and Chemical Safety Conclusion References
1 Basics of Nuclear Physics
Abstract
This chapter introduces in a quite popular form some selected questions of nuclear physics that need to be understood in order to read and absorb the main contents of the book. The reader will find a compact summary of constitution of the atomic nucleus, radioactive decay, and the main properties of nuclear radiations. The radioactive decay in which alpha or beta particles are emitted is described, in addition to gamma transitions. Energy diagrams clearly explain the patterns of decays. The chained series of transformations of heavy elements are considered because they make an important contribution to the natural external background. To understand the dangers posed by nuclear radiation, it is necessary to know the rules of interaction of radiation with matter. Relatively great attention is paid to dosimetry herein. In particular, the difference between dosimeters and radiometers is discussed. Toward the end of the chapter, the various components of the natural background are discussed. The author underlines that all life on Earth is immersed in the ocean of ionizing radiation since its origin up to the present. Keywords
Atomic nuclei protons neutrons electrons nuclear radiations alpha particles gamma quanta X rays radioactive decay radiation dosimetry radiation background interaction of radiations with matter 1.1. Peculiarities of the Processes in Microcosm
The processes in which ionizing radiations participate, as well as their production and interaction with matter, are taking place in the microcosm. It is reasonable to recall what are the peculiarities of the microcosm and how they differ from our familiar world of macroscopic bodies. 1. Microparticles exhibit not only particle properties but also wave properties. Particles can be described not only by the pulse p and the laws of movement of material bodies but by the wave length ?. The connection of these values is given by the expression of the de Broglie wave ? = h/p, where h is the Planck constant. The dimension of the Planck constant is the product of energy and time. In mechanics, such value is called action. In many problems of quantum mechanics, in the case of spherical geometry, the value h/2p = appears. Correspondingly, in the case of the de Broglie wave, the reduced value = /p is used. In the case of a wave form of movement, the principle of superposition plays an important role. It means that waves in a “collision” overlap, increasing or decreasing their amplitude depending on the phases, and then they diverge unchanged, unlike particles that in a collision change their energy and the direction of movement. 2. Electromagnetic radiation reveals not only the wave properties but also the corpuscular ones. The energy of electromagnetic quantum (photon) with frequency ? is expressed by the Planck formula E = h?. Quantum of electromagnetic radiation has no rest mass, but has a relativistic mass m = h?/c2 and a momentum p = h?/c, where c is the speed of light. At the beginning, L. de Broglie, who was the first to suggest the idea of wave properties of matter, and then other physicists, supposed that wave property is a fundamental property of matter, or that matter is “spread” over space. Correspondingly, a theory of particle behavior in the microcosm that soon appeared received the name “wave mechanics.” But then, mainly due to work by M. Born, it became evident that de Broglie waves are not the real waves of matter but they only reveal the opportunity to reveal microparticles. So, electron wave function characterizes the probability of electron finding, but electron itself is a point particle. 3. Particles in microcosm, if in bonded state, can take only definite energetic levels; that is, their states are quantized. Angular momentum and some other characteristics are also quantized. As quantization is one of the most important properties of microcosm, and “waves of matter” are virtual ones, then the name “wave mechanics” has been changed for “quantum mechanics.” Although processes in the microcosm are ruled by quantum mechanics, the quantum-mechanical concept and methods of calculation should not be necessarily used in all cases. Common experience, elementary considerations of common sense, and traditions of academic physics lead to the fact that principles of material body behavior and the principles of classical mechanics are more evident and are understood more easily and deeply than the principles of wave behavior and the concepts of quantum mechanics. The classical description is simpler and clearer than the quantum one, so it is used in all cases when accuracy of results obtained is sufficient. 4. One of the fundamental principles of quantum mechanics is the uncertainty principle – which states that the energy and pulse of a particle or the energy and duration of a process cannot be noted simultaneously with an unlimited degree of accuracy. The relations that express the uncertainty principle are as follows p ?x=h; (4.1) E ?t=h; (4.2) where p, x, E, and t are the uncertainties in the value of pulse, coordinate, energy, and process duration, respectively. 5. The particles in the microcosm have their own mechanical moment, called “spin.” Spin is a solely quantum-mechanical phenomenon; it does not have a counterpart in classical mechanics (despite that the term spin is reminiscent of classical phenomena such as a planet spinning on its axis). Spin is a vector quantity; it has a definite magnitude and a direction. The spin value is measured in fractions of . Depending on the type of a particle, it can be equal to 0, /2, , 3/2 and so on. For description of large numbers of particles, one needs to use statistical methods. It is shown in quantum mechanics that particles with a half-integer value of spin obey the Fermi–Dirac statistics and are known as “fermions,” the particles with an integer value of spin obey Bose–Einstein statistics and are known as “bosons.” The two families of particles have different roles in the world around us. A key distinction between the two families is that fermions obey the Pauli exclusion principle that was formulated by W. Pauli in 1925. According to this principle, there cannot be two identical fermions simultaneously in the limits of one quantum system, which means they cannot be present in the same place with the same energy, or in quantum language, they cannot have the same quantum numbers. In contrast, bosons have no such restriction, so they may “bunch” together even if in identical states. 6. In many cases, microparticles move with velocities that are close to the speed of light c. In this case, the rules of the theory of relativity should be considered. Such particles are called relativistic. 7. As a rule, SI units should be used exclusively in books, but in practice, in nuclear physics, SI units are never used to describe energy. In nuclear physics, the energy of particles E is mostly expressed in the extra-systemic unit “electronvolt” (eV). It is commonly used with the SI decimals prefixes – kiloelectronvolt (keV), megaelectronvolt (MeV), and gigaelectronvolt (GeV). The particles with energies in fractions of eV are the subject of chemistry and thermodynamics. The particles with energies in tens and hundreds of eV are the subject of atomic physics. Nuclear physics begins from the energies of the order of 1 keV. The energies of nuclide sources, which determine radiation practically in all applications and radiation background as well, are in the range of MeV: fractions of MeV to several MeV. 8. Most of the known radiations are unstable particles that decay over time into stable ones. Almost all unstable particles have a very small span of life – small parts of seconds. Only a free neutron lives for an average 14.8 minutes (the period of half-life T1/2 = 10.23 minutes). Physicists know only several stable particles with very great, most likely infinite, life spans. They are as follows: electron, proton (i.e., the nucleus of the hydrogen atom), and heavier nucleus. The nucleus of the helium atom is the most well known among them. At last, photon must be pointed out here. 1.2. Constitution of Nucleus
The atomic nuclei consist of positively charged protons and electrically neutral neutrons. If the electric charge is neglected, the properties of the proton and neutron are so similar that they both are called by one name – nucleon. The number of protons in a nucleus determines the electric charge and hence the number of electrons in an atom. The number of protons is numerically equal to the ordinal number of...
