Radition

In the simplest terms, radiation is energy in transit in the form of high-speed particles or electromagnetic waves. In typical usage, the word radiation means the ionizing radiation, i.e. radiation with enough energy to release electrons in the material it interacts with, such as gamma rays and beta particles. Non-ionizing radiation sources such as microwaves or radio waves can also be a hazard though. Radioactive materials, substances that give off radiation, are found naturally in everything we touch, eat, and inhale. The Earth's atmosphere is continually bombarded with cosmic radiation, some of which reaches the surface. Radiation is a known carcinogen and mutagen to which every human on the planet is exposed to every second of every day. Radiation is a natural part of our environment and it plays important roles in medicine, industry, and academic research.Instrumentation Reference Book (Third Edition)

2003, Pages 994-998

41 - Radiation

Author links open overlay panelL.W.TurnerCEng, FIEE, FRTS(Consultant Engineer)

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https://doi.org/10.1016/B978-075067123-1/50045-4Get rights and content

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Light and heat were for centuries the only known kinds of radiation. The wavelength of the radiations extends from about 100 kilometers to fractions of micrometers. The visible light radiations are near the center of the spectrum. All other radiations are invisible to the human eye. There are three main types of radiation that can originate in a nucleus—alpha, beta, and gamma radiation. This chapter also discusses radioactive decay. Radioactive isotopes are giving off energy continuously, and if the law of the conservation of energy is to be obeyed, this radioactive decay cannot go on indefinitely. The nucleus of the radioactive atom undergoes a change when a particle is emitted and forms a new and often non-radioactive product. The rate at which this nuclear reaction takes place decreases with time in such a way that the time necessary to halve the reaction rate is constant for a given isotope and is known as its half-life.Skip to Main content

Radiation Type

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External and Intermittent Leak Detection System Types

Morgan Henrie PhD, PMP, PEM, ... R. Edward Nicholas, in Pipeline Leak Detection Handbook, 2016

7.6.1 Fixed Infrared and Spectrographic Detectors

This section addresses fixed systems that use electromagnetic (EM) radiation to detect leak signatures.

One EM radiation type is the fixed infrared detector. The infrared spectrum encompasses the frequency range of 0.003–4×104 Hz with a corresponding wavelength range of 1 μm–750 mm. When infrared radiation with wavelengths of 3.3–3.5 mm encounters hydrocarbons, the hydrocarbons will absorb portions of the photon energy. Infrared leak detection systems utilize this absorption rate to identify whether hydrocarbons are present within the area that the infrared beam passes through.

One method of infrared leak detection deployment is through an open path or line-of-sight detectors. Open path systems consist of a transmitter and receiver unit separated by some distance but in line of sight of each other. The infrared signal is transmitted between the two units to determine the potential presence of hydrocarbons. In operation, the system actually transmits two infrared beams. The detection beam is set for the 3.3-μm wavelength. A second beam, called the reference beam, is transmitted at the same time as the detection beam. The reference beam wavelength is selected so that it is slightly different than the 3.3-μm wavelength used by the detection beam. The reference beam wavelength is also selected so that hydrocarbon energy absorption does not occur. The different wavelengths allow the receiving unit to compare the energy level received for each transmitted beam. Comparing the received reference beam magnitude to the detection beam level allows the system to cancel out environmental influences and identify the presence of the targeted hydrocarbon vapor, if present. This results in higher confidence that the system can detect when hydrocarbons are absorbing a portion of the detection beam infrared wavelength energy.

Open-path EM infrared detectors are very effective. At the same time, these systems have several limitations. First, the open channel system must have a clear line of sight between the transmitter and the receiver unit. If the infrared beam is blocked, then it will not function. The second major limitation is length. These systems have a finite operating distance. One vendor specifies that its system will operate up to 150 meters (approximately 492 feet).

Open channel systems are applicable for very specific and localized leak detection. The operating length limitation prohibits this technology's application over several hundreds of miles of buried pipeline.

Another type of EM infrared (IR) leak detector is known as the point IR system. This type of system is fully contained in an instrument case. Rather than test for the presence of hydrocarbons across a long distance, it tests for the presence of hydrocarbons at a fixed point or location. These systems rely on the hydrocarbon vapor entering the fixed point device and altering the infrared signal.

Fixed EM infrared detectors can be very effective. However, they also have limitations. One limitation is that the hydrocarbon vapor must enter the device. The probability that this occurs is a function of where the hydrocarbon vapor source is, wind direction, and device location. If the quantity and location of detectors are insufficient to provide full area coverage, then detection of the spill could take a long time or might never occur. These systems can generate false alarms because hydrocarbon sources other than a spill can trigger the device. However, their installation is relatively low-cost and there is minimal installation risk.

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Vehicle Communications

William B. Ribbens, in Understanding Automotive Electronics (Eighth Edition), 2017

Abstract

Communication with vehicles (while moving) began with the introduction of AM radio receivers in the 1930s. In this same general era, two-way radio communication via radio was used by law enforcement agencies. The evolution of civilian two-way radio communications advanced relatively slowly until the introduction of cellular phones. Initially, they were often referred to as bag phones since they were relatively bulky and packages in bags. The early cellular phones (now just called cell phones) had telephone-type handsets. It is widely known that the advances in cell phone technology have been very rapid. It is also well known that cell phone communication requires an infrastructure of multiple cell phone transceiver stations (called cell towers). Other wireless communications between moving vehicles and multiple fixed or moving (i.e., satellite) transceivers are developing and have been developed. In this chapter, we refer to such communication as vehicle to infrastructure (often abbreviated as (V2I)).

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Non-Traditional Machining (NTM) processes

K.G. Swift, J.D. Booker, in Process Selection (Second Edition), 2003

Process variations

•

Many types of laser are available, used for different applications. Common laser types available are: CO2, Nd:YAG, Nd:glass, ruby and excimer. Depending on economics of process, pulsed and continuous wave modes are used.

•

High pressure gas streams are used to enhance the process by aiding the exothermic reaction process, keeping the surrounding material cool and blowing the vaporized or molten material and slag away from the workpiece surface.

•

Laser beam machines can also be used for cutting, surface hardening, welding (LBW) (see 7.6), drilling, blanking, honing, engraving and trimming, by varying the power density.

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Tissue-equivalent TL Sheet Dosimetry System for Gamma-ray Spatial Dose Distribution Measurement

Nobuteru Nariyama, ... Yuhzoh Ishikawa, in Recent Advances in Multidisciplinary Applied Physics, 2005

INTRODUCTION

Recently, accelerator facilities providing beam shape radiation are increasing in number, of which the radiation types are various and the energies are distributed widely: synchrotron radiation is a low-energy x-ray beam, and the proton and heavy ion beams used for medical applications have high energies. When the beam radiation is incident to a human body intentionally or accidentally, the dose distribution is extremely localized and cannot be detected with a conventional point-type dosimeter satisfactorily. Furthermore, the spatial dose distribution changes drastically, and so even if many small dosimeters are set for the measurement, such a localized distribution cannot be measured in detail, and the highest dose also cannot be detected if accidentally irradiated. Thus the dose monitoring necessary much differs from that for the traditional radioisotopes and nuclear facilities.

In the situation, position sensitive two-dimensional dosimeters can be expected as a useful tool; several types dosimeters have been developed until the present. In early stages, thermoluminescence (TL) distribution in a millimeter-size area has been measured using a photograph camera [1]. Taking a step forward, optically stimulated luminescence (OSL) from small natural and artificial materials has been measured using a photomultiplier tube [2,3] and a CCD camera [4-6] for several tens μm resolution. For macroscopic dose distribution, a laser-heating thermoluminescent dosimeter system has been developed [7]. However, it was considered that the heat load was large and the space resolution was worse than OSL: the system has not become popular for the practical dose measurements.

The OSL is certainly a suitable method for the two-dimensional dosimeter because of the availability of narrow laser beam for the high space resolution and no heat loading. Nevertheless, rather than the space resolution, tissue-equivalent property is much more significant for the radiation dosimeters to deal with the diversities of the radiation and energies. For OSL, such a phosphor with satisfactory sensitivity has not been discovered. An imaging plate is a high-sensitive OSL detector developed for imaging; the detector shows the energy response over one hundred times higher for 50-keV photons than for Co-60 gamma rays, according to the calculations using the mass energy-absorption coefficients of BaFBr:Eu2 +. Moreover, the phosphor is known to show a strong fading [8]. The other practical used OSL phosphor of Al2O3: also exhibits increase of the energy response in the low energy region.

For the TL, two kinds of tissue-equivalent phosphors are practically used: lithium fluoride (LiF) and lithium borate. Using the phosphors, a tissue-equivalent sheet-type dosimeter is possible. When a CCD camera is used for the TL detection, a conventional ohmic-heating method is applicable, which is easier for the temperature control. Actually, such an equipment is applied to BaSO4:Eu TL sheet [9,10]. Here should it be noted that to make a sheet, TL material powder has to be mixed with a binder material, which inevitably lower the sensitivity than that of the original one, and so high-sensitive TL material is necessary. Therefore, LiF:Mg,Cu,P phosphor was chosen in the present work because of the highest sensitivity among the tissue-equivalent TL phosphors [11].

In this study, a tissue-equivalent thermoluminescent dosimeter (TLD) sheet using LiF:Mg,Cu,P was developed for dose mapping to various radiation. For the heating, a 20-cm-square plate with temperature linearity and homogeneity was also developed, and using the reader system, characteristics of the sheet TLDs were investigated.

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Radiation protection finishes for textiles

G. Rosace, in Functional Finishes for Textiles, 2015

16.7 Future trends and challenges

There is an increasing demand to develop new shielding materials that can be customized according to specific application or radiation type. In a market that is receptive to new products and suppliers, protective clothing may be attractive to companies wishing to diversify. The potential application of nanotechnology for radiation shielding should be explored in depth: it has been demonstrated that by combining the nanoparticles of hydroxylapatite, TiO2, ZnO and Fe2O3 with other organic and inorganic substances, the surfaces of the textile fabrics can be appreciably modified to achieve considerably greater abrasion resistance, water repellency, ultraviolet (UV) resistance, and electromagnetic and infrared protection properties (Sawhney et al., 2008). Nanoparticles of a clinoptilolite, a natural microporous silicate mineral having a crystalline configuration and tetrahedral structure, have been recently applied to textiles to investigate the behaviour of cotton in order to classify the processed textiles into the group of possibly radioactive–protectives (Grancaric et al., 2012). Modification of fibres based on conductive polymers seems to be another interesting approach enabling these new functionalities. However, they are inherently insoluble and infusible due to their strong intermolecular interactions. As reported by Kim et al. (2004), high quality conducting blends with conventional polymers by melt mixing or by solution casting are still in a development stage. Although conducting polymers can be produced electrochemically in fibres or film form, they are too brittle to apply on large applications. Considering this difficulty, thin coating or polymerizing conductive polymers from solutions onto the surface of plastics or textiles should be a reasonable method to create conductive textile structures. Water soluble conductive polymers are also in the phase of development by several research groups. Several parameters such as the bath temperature, the take-up speed of yarns, the duration of the treatment and the surface characteristic of the yarns influence the final result. Currently, the influence of all these parameters has to be investigated and the whole process should be optimized.

Finally, the shielding effectiveness of clothing materials is usually measured to simply evaluate the protective effectiveness in their bidimensional state. To better understand the protective performance of clothing closest to real conditions, electromagnetic simulation software will be used to analyse the damage due to electromagnetic radiation at different frequencies on the human body (Zhang and Chen, 2010).

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Future textiles for high-performance apparels

J. McLoughlin, Roshan Paul, in High-Performance Apparel, 2018

11.4.8 Radiation protection finishes

The exposure to both ionizing and nonionizing radiations can be dangerous to human beings. So there is an increasing demand to develop new shielding materials that can be customized according to specific application or radiation type. An effective radiation shield should cause a large energy loss in a small penetration distance without emission of more hazardous radiation. The focus of the research is to explore the potential application of nanotechnology on textiles for achieving radiation shielding as well as to gain protection from other hazards. It has been demonstrated that by combining various nanoparticles with other organic and inorganic substances, the textile fabrics can be modified to achieve considerably greater electromagnetic protection along with other protection properties. Modification of fibers based on conductive polymers seems to be another interesting approach for enabling these new functionalities.

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Functional finishes for textiles: an overview

R. Paul, in Functional Finishes for Textiles, 2015

1.4.6 Radiation protection finishes

Exposure to both ionizing and non-ionizing radiations can be dangerous to human beings, so there is an increasing demand to develop new shielding materials that can be customized according to specific application or radiation type. An effective radiation shield should cause a large energy loss in a small penetration distance without emission of more hazardous radiation. Furthermore, the good shielding material should have high absorption cross section for radiation and at the same time irradiation effects on its mechanical and optical properties should be negligible. In a market that is receptive to new products and technologies, this kind of protective clothing may be attractive to companies wishing to diversify.

There is a research focus to explore the potential application of nanotechnology on textiles for achieving radiation shielding as well as to gain protection from other hazards. It has been demonstrated that by combining various nanoparticles with other organic and inorganic substances, textile fabrics can be modified to achieve considerably greater electromagnetic protection along with other protection properties. Modification of fibres based on conductive polymers seems to be another interesting approach for enabling these new functionalities. Although conducting polymers can be converted into fibres, many of them are brittle. Water soluble conductive polymers are also under development.

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In Dictionary of Energy (Second Edition), 2015

radiation Physics. 1. energy transferred through space or other media in the form of particles or waves, especially electromagnetic waves; e.g., visible light, ultraviolet light, and infrared light. Certain radiation types are capable of breaking up atoms or molecules. 2. the complete process by which waves or particles are emitted, pass through a medium, and are absorbed by another body.See below.

radiation Radiation (from Latin radiare, 'to emit beams') is energy transmitted through space as particles or electromagnetic waves or the process of their emission. The most familiar forms of radiation are sunshine and alpha-rays, beta-rays, and gamma-rays emitted by radioactive substances. Particle radiation refers to the radiation of energy by means of small fast moving particles that have energy and mass. Electromagnetic radiation is emitted in discrete units known as photons and are classified (by increasing energy or decreasing wavelength) into radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma-rays. Radiation is separated into two categories, ionizing and non-ionizing, to denote the energy and danger of the radiation. Ionizing radiation is radiation in which individual particle carries enough energy to ionize an atom or molecule. Corpuscular ionizing radiation consists of fast-moving charged particles such as electrons, positrons, or small atomic nuclei. Thermal, epithermal and fast neutrons interact with atomic nuclei creating secondary ionizing radiation and are called indirectly ionizing radiation. Electromagnetic ionizing radiation includes X-rays and gamma-rays. Ultraviolet light also can ionize atom or molecule, but refers usually as non-ionizing radiation. The amount of ionizing radiation, or 'absorbed dose' is measured by the gray. One gray (Gy) is one joule of the energy deposited per kilogram of mass. Some types of radiation, such as neutrons or alpha particles, are more biologically damaging than photons or fast electrons when the absorbed dose from both is equal. To estimate this, dose equivalent, a unit called the sievert (Sv) is used. Regardless of the type of radiation, one sievert of radiation produces the same biological effect. High radiation doses tend to kill cells, while low doses tend to damage or alter the genetic code of irradiated cells. The effect of very low doses is a subject of current debate.

Valery Chernov

Universidad de Sonora, Mexico

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Nuclear Decay

M.I. Ojovan, W.E. Lee, in An Introduction to Nuclear Waste Immobilisation (Second Edition), 2014

2.10 Radionuclide Characteristics

Important characteristics of the radionuclides which are often present in radioactive wastes are given in Table 2.3. Indicated here are the decay modes, which include α and β emission, EC, isomeric transition to a lower energy (IT) and spontaneous fission (SPF). Table 2.3 also gives the major radiation energies in MeV/disintegration for the total electron (∈), gamma and X-ray photon (γ) emissions and the sum of the average energies (termed Q-values) for different radiation types in MeV/disintegration or W/Ci, which includes alpha and beta particles, discrete electrons and photons. The Q-value indicates the amount of energy that could be deposited in the form of heat in a radioactive material from each decay event if none of the radiation escaped from the material (neutrinos are not included). Problems with particular radionuclides present in waste arise from their ability to deliver high doses associated with long radioactive half-lives, high radiotoxicity (e.g. from α particle or high-energy β emission), high mobility (Section 3.2), ease of assimilation and long residence times in living organisms – for example long biological half-lives, which are defined as the necessary periods of time to evacuate one-half of absorbed elements from the organism (Chapters 9 and 10Chapter 9Chapter 10).

Table 2.3. Characteristics of Some Radionuclides

NuclideHalf-LifePrincipal Mode of DecayMajor Radiation Energies (MeV/dis)Q-valueSpecific Activity (Ci/g)Daughter(s)α∈γMeV/disW/Ci3H12.33 yearβ0.005685.68×10−33.37×10−596503He14C5730 yearβ0.04954.95×10−22.93×10−44.45714N36Cl3.01×105 yearß (98.1%)0.24602.460×10-11.458×10-33.299×10-236Ar40K1.277×109 yearß (89.33%)0.45450.15596.104×10-13.62×10-36.983×10-640Ca60Co5.271 yearß0.09582.50582.60161.541×10-2113160Ni59Ni7.5×104 yearEC0.00430.00246.72×10-33.98×10-58.079×10-259Co63Ni100.1 yearß0.01711.71×10-21.01×10-461.6863Cu79Se<6.5×104 year0.05295.29×10-23.13×10-46.966×10-279Br85Kr10.72 yearß0.25050.00222.53×10-11.50×10-3392.385Rb90Sr28.5 yearß0.19581.96×10-11.16×10-3136.490Y93mNb13.6 yearIT0.02810.00182.99×10-21.77×10-4282.693Nb94Nb2.03×104 yearß0.14541.57151.71691.018×10-21.873×10-194Mo93Mo3500 yearEC0.00510.01071.58×10-29.37×10-51.1093Nb99Tc2.13×105 yearß0.08468.46×10-25.01×10-41.695×10-299Ru106Ru1.020 yearß0.10041.004×10-15.951×10-43346106Rh107Pd6.5×106 yearß0.00939.3×10-35.5×10-55.143×10-4107Ag113Cd9.3×1015 yearß0.09339.13×10-25.412×10-43.402×10-13113In113mCd13.7 yearß (99.9%)0.18341.83×10-11.08×10-3216.8113In126Sn~1×105 yearß0.12490.05731.82×10-11.08×10-32.837×10-2126Sb125I60.14 dayEC0.01790.04236.02×10-23.57×10-417,370125Te129I1.57×107 yearß0.05560.02488.04×10-24.77×10-41.765×10-4129Xe134Cs2.062 yearß0.16391.55551.7191.019×10-21294134Ba135Cs3.0×106 year–0.05635.63×10-23.32×10-41.151×10-3135Ba137Cs30.17 yearß (94.6%)1.1761.1766.96×10-386.98137mBa133Ba10.54 yearEC0.05470.40454.592×10-12.722×10-3250.0133Cs146Pm5.53 yearEC (66.1%)0.09280.75428.47×10-15.02×10-3442.8146Ndß (33.9%)146Sm147Pm2.6234 yearß0.61966.20×10-23.67×10-4927.0147Sm151Sm90 yearß0.12511.25×10-17.41×10-426.31151Eu152Eu13.33 yearEC (72.08%)0.12751.16281.2907.646×10-3172.9152Smß (27.92%)152Gd154Eu8.8 yearß0.27941.25311.5329.081×10-3269.9154Gd155Eu4.96 yearß0.06500.06331.28×10-17.59×10-4465.1155Gd153Gd241.6 dayEC0.03990.10151.414×10-18.381×10-43526153Eu157Tb150 yearEC0.00310.00508.10×10-34.802×10-515.19157Gd158Tb150 yearEC (82%)9.02×10-15.347×10-315.08158Gdß (18%)158Dy187Re4.6×1010 yearß0.00072.591.535×10-23.823×10-8187Os210Pb22.32 yearß0.03433.43×10-22.029×10-476.30210Bi209Po102 yeara (99.74%)4.9794.96452.943×10-116.8205Pb210Po138.4 daya5.30445.3043.144×10-24.493×103206Pb226Ra1600 yeara4.77410.00350.00674.7842.836×10-29.887×10-1222Rn227Ac21.77 yearß (98.62%)0.06730.01250.00028.00×10-24.74×10-472.33227Th229Th7340 yeara4.86200.03434.8962.902×10-22.127×10-1225Ra230Th7.54×104 yeara4.66510.00044.6652.765×10-22.109×10-2226Ra232Th1.405×1010 yeara4.00560.00024.0062.375×10-21.097×10-7228Ra231Pa3.276×104 yeara4.92300.04830.03995.0112.970×10-24.723×10-2227Ac232U68.9 yeara5.30650.00025.3073.146×10-221.40228Th233U1.592×105 yeara4.81410.00550.00134.8212.857×10-29.680×10-3229Th234U2.454×105 yeara4.77320.00014.7732.829×10-26.248×10-3230Th235U7.037×108 yeara4.37850.04260.15614.5772.713×10-22.161×10-6231Th236U2.342×107 yeara4.47930.01080.00154.4922.662×10-26.469×10-5232Th238U4.468×109 yeara4.19450.00950.00134.2052.492×10-23.362×10-7234Th236Np1.550×105 yearEC (91%)0.19670.14113.38×10-12.00×10-31.317×10-2236U237Np2.140×106 yeara4.76040.06400.03274.8572.879×10-27.049×10-4233Pa236Pu2.851 yeara5.75210.01260.00205.7673.418×10-2531.3232U238Pu87.74 yeara5.48710.00990.00185.4993.2593×10-217.12234U239Pu2.411×104 yeara5.10110.00015.1013.024×10-26.216×10-2235U240Pu6563 yeara5.15495.1553.056×10-22.279×10-1236U241Pu14.4 yearß0.00010.00525.3×10-33.2×10-5103.0241Am242Pu3.763×105 yeara4.89010.00810.00144.9002.904×10-23.818×10-3238U244Pu8.26×107 yeara (99.875%)4.57510.00070.00014.5762.712×10-21.774×10-5240USPF (0.125%)Fission products241Am432.7 yeara5.48010.03040.02875.5393.283×10-23.432237Np242mAm141 yearIT (99.55%)0.02320.04030.00496.84×10-24.05×10-49.718242Ama (0.45%)238Np243Am7380 yeara5.26560.04815.31373.1496×10-21.993×10-1239Np243Cm28.5 yeara (99.76%)5.83800.11290.13166.0833.605×10-251.62239Pu244Cm18.1 yeara5.79650.00165.7983.437×10-280.90240Pu245Cm8500 yeara5.36310.13420.11785.6153.329×10-21.717×10-1241Pu246Cm4730 yeara5.37640.00720.00145.3853.192×10-23.072×10-1242Pu247Cm1.56×107 yeara4.94750.31525.2633.119×10-29.278×10-5243Pu248Cm3.40×105 yeara (91.74%)4.65244.65242.7577×10-24.251×10-3244PuSPF (8.26%)Fission products252Cf2.645 yeara (96.908%)5.93080.00510.00115.93703.5191×10-2537.8248CmSPF (3.092%)Fission products

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Modelling radionuclide transport in the environment and calculating radiation doses

M. Thorne, in Radionuclide Behaviour in the Natural Environment, 2012

Absorbed dose, equivalent dose and effective dose

In the introduction to this subsection, radiation dose has been used in a broad colloquial sense. However, for assessment purposes clear definitions are required, particularly because several conceptually different types of radiation dose quantities are used in radiological protection. The most fundamental quantity is absorbed dose, D. This is the amount of energy absorbed per unit mass of material. It has units of J kg−1, and 1 J kg−1 is given the special name gray (symbol Gy). The average absorbed dose to a tissue or organ is also designated DT,R (i.e. T for tissue and R for radiation type).

Although the gray is a well-defined physical unit, it is not adequate for radiological protection purposes. This is because various types of ionising radiation differ in the effectiveness with which they induce biological damage. Particles such as electrons only induce a low density of ionisations along their tracks and these widely separated ionisations cannot interact very effectively to induce relevant types of damage (e.g. double-strand breaks in DNA). In contrast, alpha particles induce a high density of ionisations along their tracks and are very effective at inducing damage. These distinctions in biological effectiveness are typically assessed by relating the Relative Biological Effectiveness (RBE) of a radiation to its Linear Energy Transfer (LET). The RBE is the ratio of a dose of a low-LET reference radiation to a dose of the radiation considered that gives an identical biological effect. RBE values vary with the dose, dose rate and biological endpoint considered. The LET is the amount of radiation energy deposited per unit length of path through a material (e.g. a tissue). The fundamental unit of LET is J m−1, but it is often given in keV μm−1.

Values of RBE can be measured for a wide variety of biological systems. However, for radiological protection, the wide variety of experimental results is condensed into a limited number of radiation weighting factors (wR values) that are judged to be broadly applicable in the context of the induction of stochastic effects in humans. The wR values currently recommended by the International Commission on Radiological Protection (ICRP, 2007) are summarised in Table 14.2.

Table 14.2. Radiation weighting factors

Radiation typeRadiation weighting factor, wRPhotons1Electrons and muons1Protons and charged pions2Alpha particles, fission fragments and heavy ions20NeutronsA continuous function of neutron energy, ranging from 2.5 to 20

Source: ICRP, 2007.

In an environmental context, the main radiations of interest are photons (X-rays and gamma rays), electrons and muons (the latter chiefly of relevance as a component of cosmic ray flux at ground level) and alpha particles. Thus, distinction is generally between use of a wR value of 1.0 for low-LET radiations and a value of 20 for high-LET radiations.

It is emphasised that this scheme of radiation weighting factors is grossly simplified. It does not, for example, take account of observed differences in RBE between X-rays and gamma rays, or the somewhat enhanced biological effectiveness of very low-energy beta particles (electrons) such as those emitted by tritium (3H).

If the average absorbed dose to a tissue or organ is multiplied by the appropriate radiation weighting factor, the product is termed the equivalent dose (Ht) to that organ or tissue, defined by:

HT=ΣwRDT,R

where the sum is performed over all types of radiations involved.

The unit of equivalent dose is J kg−1, but the special name in this case is the sievert (Sv).

In addition to distinguishing between different types of radiation, it is important to recognise that the various tissues and organs of the body differ in their sensitivity to the induction of stochastic effects. The ICRP (2007) takes these differences in sensitivity into account by the use of tissue weighting factors (wT). The currently recommended values are listed in Table 14.3. The tissue weighting factors are set to sum to 1.0.

Table 14.3. Tissue weighting factors

Tissue or organTissue weighting factor, wTBone marrow (red), colon, lung, stomach,0.12breast, remainder tissues⁎Gonads0.08Bladder, oesophagus, liver, thyroid0.04Bone surface, brain, salivary glands, skin0.01

⁎Remainder tissues comprise adrenals, extra-thoracic region of the respiratory system, gall bladder, heart, kidneys, lymphatic nodes, muscle, oral mucosa, pancreas, prostate, small intestine, spleen, thymus and uterus/cervix.

Source: ICRP, 2007.

The effective dose, E, is defined by summing the products of equivalent doses in each of the tissues and organs of the body and the tissue weighting factors for those tissues and organs. Thus:

E=ΣwTHT=ΣwTΣwRDT,R

where the sum is performed over all tissues and organs of the human body considered to be sensitive to the induction of stochastic effects.

If several radiation types need to be considered, this summation is simply extended as shown to a double summation over radiation types and tissues and organs.

The unit of effective dose is J kg−1, and the special name is the sievert (Sv), as it is for equivalent dose.

Because the values of wT sum to 1.0, in the case of uniform whole body irradiation the effective dose is equal to the equivalent dose in any tissue or organ.

Effective dose and measures derived from it are the quantities of greatest relevance in evaluating the health impacts of environmental radioactivity (though equivalent doses may be of interest in some specific contexts, e.g. evaluating the risks of induction of thyroid cancer following the Chernobyl accident). Under the LNT hypothesis, the risk of inducing stochastic effects is directly proportional to the effective dose received. In setting the tissue weighting factors, consideration was given to the induction of fatal cancer, non-fatal cancer and genetic effects, with a weighting for the assessed severity of each condition. Thus, effective dose is associated with a quantity termed health detriment that includes contributions from each of these conditions. In general terms, health detriment can be thought of as equivalent to fatal cancer risk, with the other conditions taken into account by considering their severity relative to fatal cancer. The ICRP (2007) has estimated that the detriment to a population of all ages is 5.7 × 10−2 per Sv of effective dose.

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Radiation Type

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Amplifier

Photodiodes

Gamma Ray

Photons

Ionising Radiation

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External and Intermittent Leak Detection System Types

Morgan Henrie PhD, PMP, PEM, ... R. Edward Nicholas, in Pipeline Leak Detection Handbook, 2016

7.6.1 Fixed Infrared and Spectrographic Detectors

This section addresses fixed systems that use electromagnetic (EM) radiation to detect leak signatures.

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Vehicle Communications

William B. Ribbens, in Understanding Automotive Electronics (Eighth Edition), 2017

Abstract

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Non-Traditional Machining (NTM) processes

K.G. Swift, J.D. Booker, in Process Selection (Second Edition), 2003

Process variations

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Laser beam machines can also be used for cutting, surface hardening, welding (LBW) (see 7.6), drilling, blanking, honing, engraving and trimming, by varying the power density.

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Tissue-equivalent TL Sheet Dosimetry System for Gamma-ray Spatial Dose Distribution Measurement

Nobuteru Nariyama, ... Yuhzoh Ishikawa, in Recent Advances in Multidisciplinary Applied Physics, 2005

INTRODUCTION

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Radiation protection finishes for textiles

G. Rosace, in Functional Finishes for Textiles, 2015

16.7 Future trends and challenges

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Future textiles for high-performance apparels

J. McLoughlin, Roshan Paul, in High-Performance Apparel, 2018

11.4.8 Radiation protection finishes

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Functional finishes for textiles: an overview

R. Paul, in Functional Finishes for Textiles, 2015

1.4.6 Radiation protection finishes

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In Dictionary of Energy (Second Edition), 2015

Valery Chernov

Universidad de Sonora, Mexico

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Nuclear Decay

M.I. Ojovan, W.E. Lee, in An Introduction to Nuclear Waste Immobilisation (Second Edition), 2014

2.10 Radionuclide Characteristics

Table 2.3. Characteristics of Some Radionuclides

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Modelling radionuclide transport in the environment and calculating radiation doses

M. Thorne, in Radionuclide Behaviour in the Natural Environment, 2012

Absorbed dose, equivalent dose and effective dose

Table 14.2. Radiation weighting factors

Source: ICRP, 2007.

If the average absorbed dose to a tissue or organ is multiplied by the appropriate radiation weighting factor, the product is termed the equivalent dose (Ht) to that organ or tissue, defined by:

HT=ΣwRDT,R

where the sum is performed over all types of radiations involved.

The unit of equivalent dose is J kg−1, but the special name in this case is the sievert (Sv).

Table 14.3. Tissue weighting factors

Source: ICRP, 2007.

The effective dose, E, is defined by summing the products of equivalent doses in each of the tissues and organs of the body and the tissue weighting factors for those tissues and organs. Thus:

E=ΣwTHT=ΣwTΣwRDT,R

where the sum is performed over all tissues and organs of the human body considered to be sensitive to the induction of stochastic effects.

If several radiation types need to be considered, this summation is simply extended as shown to a double summation over radiation types and tissues and organs.

The unit of effective dose is J kg−1, and the special name is the sievert (Sv), as it is for equivalent dose.

Because the values of wT sum to 1.0, in the case of uniform whole body irradiation the effective dose is equal to the equivalent dose in any tissue or organ.

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