8/22/2023 0 Comments Radioactive elementsNuclear fallout is the distribution of radioactive contamination by the 520 atmospheric nuclear explosions that took place from the 1950s to the 1980s. For a discussion of environmental contamination by alpha emitters please see actinides in the environment. In cases that radioactive material cannot be contained, it may be diluted to safe concentrations. Radioactive contamination may also be an inevitable result of certain processes, such as the release of radioactive xenon in nuclear fuel reprocessing. For example, if a radionuclide used in nuclear medicine is spilled (accidentally or, as in the case of the GoiĆ¢nia accident, through ignorance), the material could be spread by people as they walk around. It may occur due to the release of radioactive gases, liquids or particles. Radioactive contamination can be due to a variety of causes. The sources of radioactive pollution can be natural or man-made. The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere. Plot of atmospheric 14C, New Zealand and Austria. Global airborne contamination Atmospheric nuclear weapon tests almost doubled the concentration of 14C in the Northern Hemisphere. Cases of widespread radioactive contamination include the Bikini Atoll, the Rocky Flats Plant in Colorado, the area near the Fukushima Daiichi nuclear disaster, the area near the Chernobyl disaster, and the area near the Mayak disaster. A spilled vial of radioactive material like uranyl nitrate may contaminate the floor and any rags used to wipe up the spill. Following an atmospheric nuclear weapon discharge or a nuclear reactor containment breach, the air, soil, people, plants, and animals in the vicinity will become contaminated by nuclear fuel and fission products. The sources of radioactive pollution can be classified into two groups: natural and man-made. It is important to be clear that the contamination gives rise to the radiation hazard, and the terms "radiation" and "contamination" are not interchangeable. The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. Such contamination presents a hazard because the radioactive decay of the contaminants, produces ionizing radiation (namely alpha, beta, gamma rays and free neutrons). Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirable (from the International Atomic Energy Agency (IAEA) definition). The difficult cleanup job will take 40 or more years, and cost tens of billions of dollars. As of 2013, the Fukushima nuclear disaster site remains highly radioactive, with some 160,000 evacuees still living in temporary housing, and some land will be unfarmable for centuries.
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