Uranium background radiation from

We are constantly exposed to background radiation from cosmic radiation (interaction of energy from the sun with the earth s atmosphere), terrestrial radiation from breakdown of uranium in the soil, and natural internal radiation in our bodies from carbon-14 that is present at birth. Man-made radiation sources include diagnostic X-rays, nuclear medicine (bone scans, thyroid scans, etc.), radiation therapy for cancer, nuclear power facilities, and nuclear weapons. 

Based on this same data base, the NRC determined that the maximum uranium dose equivalent of workers on-site was 28 mrem (0.28 mSv). The maximum uranium dose equivalent of off-site individuals was 1.4 mrem (0.014 mSv). However, these radiological doses were small compared to the background radiation level of 106 mrem/year (1.06 mSv/year) in the area from which the data were collected (USNRC 1986). 

Another element that contributes to our background radiation, and hence to our risks of radiation-caused damage, is radon. Radon-222, the most common isotope of radon, is radioactive, with a half-life of 3.82 days. It is a product of the uranium decay series (see Figure 13.5) and results from the alpha decay of radium-226. 

The presence of radiation in the workplace - which is an inevitable consequence of the radioactivity of uranium - requires that additional safety precautions be taken over and above those observed in other similar workplaces. There are generally three sources from which radiation exposure may occur (i) radiation emitted from uranium ore in-situ and/or during handling (ii) airborne radiation resulting from the decay of radon gas released from the ore and uranium dust and (iii) contamination by ore dust or concentrate. Radiation levels around uranium mining and milling facilities are quite low - for the most part only a few times the natural background levels - and they decrease rapidly as the distance from... 

For a signal based on measurement of the positron alone, the background is taken to be any event detectable by Cerenkov radiation and depositing 2 MeV or more of energy in the detector. At ranges down to about 10 km, we v l see that backgrounds from uranium, thorium, and radon contamination in the water exceed the tolerable background rates just defined. This restriction is relaxed considerably by the addition of a dopant. 

Uranium concentration thus determined is usually given in units of ppm eU (parts per million of equivalent uranium) as a raninder that this indirect measurement is based on the daughter nuclide that is assumed to be in secular equilibrium with U-238 (IAEA-TECDOC1363 2003). The data from aerial survey may be corrected for effects arising from the background (cosmic radiation and aircraft radioactivity), altitude (changes in pressure, temperature, and air density effects), the presence of... 

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