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Posted by / 01-Nov-2017 07:24

Cosmogenic nuclide dating

Long-lived radioactive elements such as uranium, thorium and potassium and any of their decay products, such as radium and radon are examples of NORM.These elements have always been present in the Earth's crust and atmosphere, and are concentrated in some places, such as uranium orebodies which may be mined.Material giving rise to these enhanced exposures has become known as naturally occurring radioactive material (NORM).NORM is the acronym for Naturally Occurring Radioactive Material, which potentially includes all radioactive elements found in the environment.However, the term is used more specifically for all naturally occurring radioactive materials where human activities have increased the potential for exposure compared with the unaltered situation.Concentrations of actual radionuclides may or may not have been increased; if they have, the term Technologically-Enhanced (TENORM) may be used.For most human activities involving minerals and raw materials, the levels of exposure to these radionuclides are not significantly greater than normal background levels and are not of concern for radiation protection.However, certain work activities can give rise to significantly enhanced exposures that may need to be controlled by regulation.

For most people, cosmogenic NORM barely contributes to dose – perhaps a few tens of microsieverts per year.

This means that material which is considered radioactive waste in one context may not be considered so in another.

Also, that which may constitute low-level waste in the nuclear industry might go entirely unregulated in another industry (see section below on recycling and NORM).

Excluding uranium mining and all associated fuel cycle activities, industries known to have NORM issues include: Another NORM issue relates to radon exposure in homes, particularly those built on granitic ground.

Occupational health issues include the exposure of flight crew to higher levels of cosmic radiation, the exposure of tour guides to radon in caves, exposure of miners to radon underground, and exposure of workers in the oil & gas and mineral sands industries to elevated radiation levels in the materials they handle.

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