Radiation Protection

William H. Hallenbeck

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000157963
• Edition: 1
• Topic: Tecnologia e ingegneria
• Subtopic: Scienze applicate

This text/reference provides an excellent introduction to fundamental topics in radiation protection, including energetics, kinetics, interaction, external radiation protection, dosimetry, standards, and measurement. Chapters on radioactive waste and radon, topics not normally covered in introductory texts, have been incorporated as well. An extensive glossary of terms, abbreviations, acronyms, physical constants, units, and unit conversions provides a ready source of frequently needed information. Several appendices contain specifications and vendors for commercially available portable radiation survey instruments, personal dosimeters, and radon/radon progeny monitors.

CHAPTER 1

Introduction

An element is characterized by the number of protons in the nucleus (atomic number, Z). There are 106 known elements with 106 unique atomic numbers. See Table 1.1 for a list of the elements. All elements with Z > 92 are man-made. Each element has multiple naturally occurring and/or man-made isotopes. Isotopes are atoms with the same atomic number but different numbers of neutrons (N) and therefore different sums of protons and neutrons (mass numbers, A). They have the same chemical properties but may differ in their nuclear properties.

An atom or nuclide is characterized by its atomic number, neutron number, mass number, and the stability of the nucleus. There are over 1600 nuclides of which about 300 are stable. Of the unstable nuclides (radionuclides), about 80 occur naturally with the remainder being man-made. The existence of an unstable nuclear energy state must be long enough to be observed in order for it to be counted as a radionuclide. Unstable nuclei have halflives which range from fractions of a second to billions of years. All nuclides with Z > 83 are unstable and therefore radioactive.

Radioactivity is a property of certain unstable nuclides which allows the attainment of a more stable nuclear state by either spontaneous emission of a high energy particle and photon or spontaneous nuclear fission. Nuclear instability is a function of nuclear properties only and cannot be altered by temperature, pressure, chemical bonding, or magnetic or electric fields. Nuclear emissions are able to ionize atoms and therefore are referred to as ionizing radiation. Ionizing radiation refers to photons or particles which have sufficient energy to remove orbital electrons from an atom and includes high energy photons (x-ray and gamma) and high energy particles (alpha, beta, electrons, protons, and neutrons). The term ionizing radiation does not include sound or radio waves or visible, infrared, or ultraviolet light. The major sources of exposure to ionizing radiation are as follows:

• Natural: cosmic, cosmogenic, terrestrial, and internal

• Human-induced: medical and dental diagnosis and therapy; industrial activities; military activities; research activities; consumer products; and air travel

Table 1.1. Elements, Symbols, and Atomic Numbers (Z)^a

Element	Symbol	Z	Element	Symbol	Z
actinium	Ac	89	dysprosium	Dy	66
aluminum	AI	13	einsteinium	Es	99
americium	Am	95	erbium	Er	68
antimony	Sb	51	europium	Eu	63
argon	Ar	18	fermium	Fm	100
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