Radioactivity background radiation

Safety considerations are based on the magnitude of the half-life, shielding, distance from the radioactive source, time of exposure, and type of radiation emitted. We are never entirely free of the effects of radioactivity. Background radiation is normal radiation attributable to our surroundings. 

Background Radiation. If the radiation from a radioactive source is measured, the spectmm also includes contributions from the radiations from the surrounding environment. This includes radiations from the radioactivity in the materials in and around the detector, including the stmcture of the building or nearby earth. There is also cosmic radiation that comes from space and interacts with the earth and atmosphere to produce radiations that may enter the detector, and thus is observed. 

There is always some level of ambient radioactivity in an environment. This radiation is known as background radiation. Measure and record the background activity by recording the counts registered by the gamma ray detector in 30-s intervals for 5 min. Record the data in Data Table 1. 

Measure background radiation and radiation emitted by a radioactive isotope. 

Radiation exposure from both natural and human sources varies widely. Background radiation depends on the local geology and elevation. Areas where radioactive rocks are located close to the surface or where mining has exposed mineral deposits have higher background levels. Higher... 

Background Radiation amount of natural radiation detected in the absence of nonnatural radioactive sources Base a substance that yields hydroxide ions in solution or accepts protons Becquerel SI unit for activity equal to one disintegration per second, abbreviated Bq... 

Figure 19. Spectral analysis of radioactivity in a sample of human liver. Two radionuclides, 137Cs and °K, were detected. The unidentified photopeaks represent background radiation...

Reduction of background radiation owing to natural radioactivity in the metal parts of the detector chamber and shielding can be reduced as shown by using electrolytic quality metals. In addition, backscatter can be reduced significantly by improvements in the counting geometry. These improvements are worthy of consideration. 

K is a (3 -emitting nuclide that is the predominant radioactive component of normal foods and human tissue. Due to the 1460-keV 7 ray that accompanies the (3 decay, it is also an important source of background radiation detected by 7-ray spectrometers. The natural concentration in the body contributes about 17 mrem/y to the whole body dose. The specific activity of 40K is approximately 855 pCi/g potassium. Despite the high specific activity of 87Rb of 2400 pCi/g, the low abundance of rubidium in nature makes its contribution to the overall radioactivity of the environment small. 

Radioactive contamination as some background radiation from natural sources, such as radon, occurs in some regions of the world, but there is particular concern over the contamination of surface water and groundwater by radioactive compounds generated by the production of nuclear weapons and by the processing of nuclear fuel. Many of these areas have remained unrecognized because of government secrecy. 

Exempt Radioactive Wastes. The radioactive waste classification system in the United States does not include a general class of exempt waste (see Table 1.1). Rather, many products and materials that contain small amounts of radionuclides (e.g., specified consumer products, liquid scintillation counters containing 3H and 14C) have been exempted from requirements for use or disposal as radioactive material on a case-by-case basis. The various exemption levels are intended to correspond to low doses to the public, especially compared with dose limits in radiation protection standards for the public or doses due to natural background radiation. However, the exemption levels are not based on a particular dose, and potential doses to the public resulting from use or disposal of the exempt products and materials vary widely. 

A second consideration that has been important, at least implicitly, in developing classification systems for radioactive waste is natural background radiation. The presence of a ubiquitous and unavoidable background of radiation and its description in terms of radiation dose provide a measure of the significance of potential exposures of radiation workers and members of the public to any radioactive waste. Levels of radiation in waste materials compared with levels of natural background radiation have played an important role in radioactive waste classification. 

Outputs from the LSC must be corrected for background radiation and counting efficiency. The parts-per-million (ppm) equivalent to the radioactive chemical in a biological, soil or water sample can then be determined by accounting for aliquot size, specific activity, and other correction factors specific for the sample. Partitioning characteristics and chromatographic data can be treated in a like manner. Although many... 

Humans were exposed to naturally occurring background radiation of course, from sunlight, cosmic rays, and the decay of naturally occurring radioactive elements. Pauling agreed with most geneticists of the day that this... 

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