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Radiochemistry
Radioactive materials encountered in the environment arise from numerous sources including both man-made and natural materials. Naturally occurring radioactive material (NORM) contains radioactive nuclides from the decay of uranium and thorium. NORM frequently form as scale in pipes or monitoring wells. Insoluble calcium compounds are formed and radium (a decay product of uranium and thorium which has chemistry similar to calcium) co-precipitates. Under some conditions, uranium and thorium can also co-precipitate. Daughter products of radium such as various isotopes of radon, polonium, bismuth, and lead are also deposited in the scale. NORM is often associated with petroleum production, phosphate and titanium dioxide mining, and with coal ash. Treatment and disposal of materials contaminated with NORM is strictly controlled by the NRC and the EPA.
Radiation detectors are extremely sensitive with counting efficiencies of close to 100% for some types of radiation. This is possible because of the large amounts of energy deposited in the detector by the radiation. Selection of the type of detector used is primarily based on the type (and hence the penetration power) of radiation. Alpha particles have little penetrating ability and are best detected by thin-window or windowless gas proportional counting or by liquid scintillation. Beta particles have limited penetrating ability and are best detected by liquid scintillation. Gamma rays have high penetrating ability and are best detected with semi-conductor counters such as GeLi or HPGe.
Information on Radiochemical Analyses is available on the world wide web.
DOE Methods for Evaluating Environmental and Waste Management Samples.
Information on Radiation Protection and NORM is available on the world wide web.
The EPA provides a search engine for documents viewing and online ordering service.
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Last update: August 31, 2003.