China
Africa
Explore chapters and articles related to this topic
Radiation units
Published in Alan Martin, Sam Harbison, Karen Beach, Peter Cole, An Introduction to Radiation Protection, 2018
Alan Martin, Sam Harbison, Karen Beach, Peter Cole
A further complication is that different organs and tissues have differing sensitivities to radiation. To deal with the very common situation in which the body is not uniformly exposed, another concept is needed to assist in combining the effects of exposure of different organs of the body to give an overall measure of the detriment. This is called effective dose, E, and is obtained by summing the equivalent doses to all tissues and organs of the body multiplied by a weighting factor wT for each tissue or organ. This is written as follows: E=∑THTwTwhere HT is the equivalent dose in tissue T. The concept of detriment and the basis of the organ weighting factors is discussed further in Chapter 4, Section 4.8. It should be noted that effective dose is also expressed in units of sieverts.
Space Radiation and Its Biological Effects
Published in Paul R. Bolton, Katia Parodi, Jörg Schreiber, Applications of Laser-Driven Particle Acceleration, 2018
Günther Reitz, Christine E. Hellweg
Usually, the absorbed dose is the basic quantity to measure radiation exposure. The absorbed dose is the quotient of the energy deposited by ionizing radiation within an elemental volume to the mass of matter in that volume. The absorbed dose is measured in units of Gray (Gy) (1 Gy = 1 J/kg [= 100 rad]). Whereas different radiation qualities produce the same type of effect, the magnitude of the effect per unit of absorbed dose can be different. For radiation protection, the quality factor (Q) was introduced in order to account for the different relative biological efficiencies (RBEs) of different types of ionizing radiation. This factor depends not only on appropriate biological data, but primarily it reflects a judgement concerning the importance of the biological endpoints. Q is defined in dependence of the linear energy transfer (LET). It is set to 1 for LET < 10 keV/μm, in the LET range from 10–100 keV/μm to 0.32* LET–2.2 keV/μm and for LET > 100 keV/μm to 300/(LET)0.5 [ICRP 1991]. The dose equivalent at a point is defined as the product of absorbed dose and Q. The quantity effective dose equivalent [ICRP 2013] is the sum of all organ doses which can be calculated as product of Q and absorbed dose by additionally applying tissue weighting factors as defined in ICRP103 [ICRP 2007]. The effective dose equivalent is given in units of Sievert (Sv) (1 Sv = 1 J/kg [=100 rem]).
Application of ICRP Biokinetic Models to Depleted Uranium
Published in Alexandra C. Miller, Depleted Uranium, 2006
The risk of harm per mSv differs between organs: for example it is lower for the liver than for the lungs. To take account of this while obtaining an estimate of the overall risk of harm to a person, the equivalent dose to each important organ or tissue is multiplied by a factor (the tissue weighting factor, symbol wT, Table 11.1). This factor can be thought of as representing the risk of harm per mSv to the tissue, compared to the risk of harm per mSv to the whole body. The sum of the weighted tissue equivalent doses is called the effective dose, and is also expressed in Sv. Effective dose provides a measure of the risk of harm resulting from irradiation of a person, taking account of different types of radiation and different doses to different organs. It is, therefore, a useful standardized measure of the risks from exposures to radiation, especially those resulting from intakes of radionuclides, which will often result in very different doses to different tissues. The primary standards of radiation protection (limits and constraints) are mainly expressed in terms of effective dose.
A Framework for Event Detection in Nuclear Facilities Using Wireless Sensors and Actors Networks
Published in Nuclear Technology, 2022
Mohamed Yehia Habash, Nabil M. A. Ayad, Abd Elhady A. Ammar
According to International Atomic Energy Agency publications, the working areas inside any nuclear facility are classified into two types, controlled and supervised areas, whenever there is exposure to occupational radiation. Further, the controlled area can be classified into multiple zones according to its radiation levels. For example, zone one has high radiation levels, and access to it is normally prohibited and may be permitted under certain conditions, such as reactor shutdown. So the threshold value, which is used to detect new events for each radiation detector inside the nuclear plant in different areas, is not the same. This is to control occupational exposure and to make sure that the relevant dose limits are not exceeded. For workers over the age of 18 years, an effective dose is 20 mSv per year (100 mSv in 5 years) and 50 mSv in any single year. For the public, an effective dose is 1 mSv per year. In case an event is detected, the central device will trigger the alarm system of the monitoring and control system to alert the operator to take corrective action.
Short-Term Assessment of Radiological Impact and Potential Risk to Workers and Public from Argonaut Nuclear Reactor Accidental Release
Published in Nuclear Technology, 2021
Paula C. Souza, André S. Aguiar, Adino Heimlich, Celso M. F. Lapa, Fernando Lamego
The effective dose is the primary quantity of radiation protection, which characterizes the exposure of an individual to both internal and external radiation sources in an independent manner from the individual’s body-related parameters (sex, age, physiology, etc.). The basic parameters of biokinetic models describing the fate of inhaled and ingested radionuclides to reference individuals, collectively referred to as reference man, are used in the calculation of dose coefficients for the reference worker and members of the public.9 Thus, the effective dose is not an individual-specific quantity, but rather it is the dose for a reference person under the specified exposure scenarios. For instance, the part of the body exposed, the delivery time span of the radiation dose, and the type of radiation involved are some of the major exposure factors. The effective dose rate (DR) calculation for the exposure under scrutiny considered only the pathways of inhalation and immersion in the plume, disregarding the doses by ingestion and external doses due to depositions on the soil, on the clothes, and on the bodies of individuals. It can be calculated using Eq. (9):
Radiation Protection Design and Licensing for an Experimental Fusion Facility: The Italian and European Approaches
Published in Fusion Science and Technology, 2019
S. Sandri, G. M. Contessa, M. Guardati, M. Guarracino, R. Villari
Both EU Directive 59/13 and the National Italian Law recommend the effective dose limits reported in the second column of Table I. Observing basic ethical principles, population and NRW are considered the same kind of individual with respect to exposure to ionizing radiation. Radiation worker exposure is limited to 20 mSv of annual effective dose, and the RW exposure of Subcategory B is limited to 6 mSv of the same quantity. The same categories of people must be exposed to levels of equivalent dose lower than limits to the organs or tissues reported in Table II. These limits are particularly important for specific exposure scenarios that are not common for DTT workers and are reported here for completeness purposes only.