Background radiation normal

In addition to the background radiation normally found at the surface of the Earth, NORM can also be brought to the surface in the natural gas production process. When NORM is associated with oil and natural gas production, it begins as small amounts of uranium and thorium within the rock. These elements, along with some of their decay elements, notably radium-226 and... 

Only in a few instances have the exposures been sufficiently marked to allow attribution, as in the case of a heavily exposed survivor of the A-bombings in Japan who subsequently developed leukemia. From the magnitude of the survivor s radiation exposme and fiwm epidemiological data on the incidence of leukemia in the population at the same exposure level, we might infer that the survivor s increase in risk corresponded to a 2 percent lifetime incidence, in contrast to the normal lifetime leukemia incidence of about 0.5 percent. The attribution would then be 2/2.5, or 80 percent, leaving 20 percent for background radiation and other causes. 

A friend checks the local background radiation with a Geiger counter, which ticks audibly. Another friend, who normally fears most that which is understood least, makes an effort to keep away from the region of the Geiger counter and looks to you for advice. What do you say ... 

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. 

Quality assurance (QA) measurements also are performed with a set of QA gamma-ray sources to confirm that the radiation detection instrument is functioning normally. The measurements are performed at regular intervals and the results are plotted to show the mean value and random deviations by 1 and 2 standard deviations (cr and 2cr). The factors that are considered include the count rate at characteristic control source peaks, the resolution of these peaks, and the background radiation shown by the detector. Any significant deviations beyond the 2-sigma values on the control charts require a repeated measurement and - if confirmed - corrective actions before further measurements are performed. 

Exposure incurred by members of the public from radiation sources, excluding any occupational or medical exposure and the normal local natural background radiation but including exposure from authorised sources and practices and from intervention situations. 

The beam of secondary radiation issuing from the sample consists largely of fluorescent radiation, but there are some other weak components present as well. These are coherent scattered radiation, coherent diffracted radiation, and incoherent (Compton modified) radiation. These components appear as a background on which the spectral lines are superimposed. This background is normally low (see Fig. 15-3), but it may become rather high if the sample contains a large proportion of elements of low atomic number, because the sample will then emit a large amount of Compton modified 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. 

A resultant spectrum is shown in Fig. 2.5 where it is compared with the normal transmission spectrum. The method has the advantage of being more selective in the presence of strong background radiation since the latter will not have a time distribution containing the modulation frequency. However, strong sources are required to obtain the best results, and it is unlikely that the technique will ever replace the very popular velocity-scan systems. 

Background. Radiation induced hepatitis was first described in the 1960s [8] and results in various degrees of hepatic decompensation. It is a well recognized complication of external beam radiation that encompasses the liver [9] since it involves the irradiation of normal parenchyma beyond that which can be tolerated (35 Gy when exposed to uniform radiation fields). However, it is a rare complication after microsphere treatment since this technique allows the safe delivery of radioactive particles to liver tumors with healthy liver tissue sparing [10]. Doses greater than 70 Gy to liver tumors can be delivered without involving the normal liver tissue [11]. 

Radiation is regarded by many people with special fear. Of course, everyone encounters radiation from many sources throughout life and there is radiation in our own bodies, from outer space and from our surroundings, with which our bodies appear to cope extremely well. The background levels vary considerably from place to place, but the records do not show any correlation between the incidents of radiation-related diseases (cancer and leukaemia) and the level of background radiation. All nuclear plants involve some release of radioactive material, but the effect on the environment corresponds to a very small fraction of the normal background, even near the plant. The effect of radiation depends on its intensity, duration and type and the age, food and living habits of individuals. 

Sources of background radiation, which we receive during normal daily life, fall into two categories man-made and natural (Figure 13.6). Of these. 

Normal background radiation from all sources produces 2 dps to 3 dps. (a) True, (b) False. 

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