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Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volts (eV), which is enough to ionize atoms and molecules and break chemical bonds. This is an important distinction due to the large difference in harmfulness to living organisms.
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.
The unit of radioactivity from the System International of units (SI system) is the becquerel (Bq) defined as the radioactive decay or disintegration of one radionuclide per second. Radioactivity is a measure of the total, local rate of radionuclides decaying per unit time and is dependent upon the total number of atoms, decay constants , and ...
Surface contamination may either be fixed or "free". In the case of fixed contamination, the radioactive material cannot by definition be spread, but its radiation is still measurable. In the case of free contamination, there is the hazard of contamination spread to other surfaces such as skin or clothing, or entrainment in the air.
R. Radiation detection; Radiation portal monitor; Radiation therapy; List of radioactive nuclides by half-life; Radioactive source; Radioactive tracer; Radioactive waste
The distribution coefficient K d is the ratio of the soil's radioactivity (Bq g −1) to that of the soil water (Bq ml −1). If the radioactivity is tightly bonded to by the minerals in the soil then less radioactivity can be absorbed by crops and grass growing in the soil. Cs-137 K d = 1000; Pu-239 K d = 10000 to 100000; Sr-90 K d = 80 to 150 ...
Radiobiology (also known as radiation biology) is a field of clinical and basic medical sciences that involves the study of the action of radioactivity on biological systems. The controlled action of deleterious radioactivity on living systems is the basis of radiation therapy.
Radioactivity originating from the Northern Hemisphere [12] is observable dating back to the mid-20th century. Some highly toxic radionuclides have particularly long radioactive half-lives (up to as many as millions of years in some cases [2]), meaning they will virtually never disappear on their own. The impact of these radionuclides on ...