Table 1: Radiological characteristics of cosmogenic NORM NORM and cosmic radiation account for over 85% of an ‘average individual’s’ radiation exposure.
Over time, as potential NORM hazards have been identified, these industries have increasingly become subject to monitoring and regulation.
However, there is as yet little consistency in NORM regulations among industries and countries.
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.
Terrestrial NORM consists of radioactive material that comes out of the Earth’s crust and mantle, and where human activity results in increased radiological exposure.
The materials may be original (such as uranium and thorium) or decay products thereof, forming part of characteristic decay chain series, or potassium-40.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.By contrast, terrestrial NORM – especially radon – contributes to the majority of natural dose, usually over 1000 microsieverts (1 m Sv) per year.Some of the main comsogenic nuclides are shown in Table 1, carbon-14 being important for dating early human activities.The acronym TENORM, or technologically enhanced NORM, is often used to refer to those materials where the amount of radioactivity has actually been increased or concentrated as a result of industrial processes.