background radiation
background radiation
| Noun | 1. | background radiation - radiation coming from sources other than those being observed |
| 单词 | background radiation | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 释义 | background radiationbackground radiation
background radiationbackground radiationSee cosmic background radiation; microwave background radiation.Background Radiation(also natural radiation, natural background radiation), the ionizing radiation from cosmic rays and naturally occurring radionuclides. Cosmic rays are streams of high-energy particles that enter the earth’s atmosphere from outer space. Naturally occurring radionuclides, which belong to the group of highly dispersed elements, are always present in the environment (seeRADIOACTIVITY OF ROCKS, RADIOACTIVITY OF WATER, and RADIOACTIVITY IN THE ATMOSPHERE) and in plants and animals. All organisms are subjected to background radiation; the average annual doses to which humans are subjected are given in Table 1. Depending on the height above sea level and the quantity of radionuclides in the environment, the background radiation varies within wide limits. In areas with a high concentration of radionuclides, the level can exceed 1,000 millirads per year (mrad/yr). Life appeared and developed on earth under conditions that included ionizing radiation. The biological effect of background radiation, however, has not yet been definitively established. It is believed that the radiation plays a part in some mutations, that is, changes in heredity, in animals and plants.
Nuclear explosions and the discharge into the environment of wastes from nuclear power plants and certain other enterprises using radioactive materials have raised the level of background radiation. Annual doses from global radioactive fallout have ranged up to tens of millirads. For the most part, these doses are determined by measuring the quantity of the artificial radionuclides 90Sr and 137Cs entering the body. In regions receiving local fallout, the doses of external and internal radiation are higher. Here, an important part is played by short-lived isotopes of fission products (131J, 89Sr, 140Ba). An increase in background radiation can lead to a buildup of harmful mutations in humans and other organisms. REFERENCESSivintsev, Iu. V. Fonovoe obluchenie chelovecheskogo organismo. Moscow, 1960.Belousova, I. M., and Iu. M. Shtukkenberg. Estestvennaia radioaktivnost’. Moscow, 1961. Moiseev, A. A., and V. I. Ivanov. Spravochnik po dozimetrii i radiatsionnoi gigiene, 2nd ed. Moscow, 1974. Ionizing Radiation: Levels and Effects. A Report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly (with annexes), vol. 1. New York, 1972. I. IA. VASILENKO background radiation[′bak‚grau̇nd ‚rād·ē′ā·shən]background radiationback·ground ra·di·a·tionbackground radiationThe amount of ionising (electromagnetic) radiation to which a person is exposed from natural sources, including terrestrial radiation due to natural radionuclides in the soil (e.g., radon), cosmic radiation and fallout in the environment from anthropogenic sources.background radiationRadiation The amount of ionizing-electromagnetic radiation to which a person is exposed from natural sources including terrestrial radiation due to natural radionuclides in the soil–eg, radon, cosmic radiation, and fallout in the environment from anthropogenic sources. See Radon.back·ground ra·di·a·tion(bak'grownd rā'dē-ā'shŭn)back·ground ra·di·a·tion(bak'grownd rā'dē-ā'shŭn)background radiation
Words related to background radiation
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