Alcoa of Australia Residue Management
 
Residue and Naturally Occurring Radioactive Materials (NORM)
Bauxite contains small amounts of naturally occurring radioactive trace elements, consistent with those found in the rocks and soils of the Darling Range.  
 
Naturally Occurring Radioactive Materials (NORM) is the term used to describe materials that contain radionuclides that exist in the natural environment.  These are found in a wide variety of sands, clay and soils, rocks, groundwater, coal, oil & gas, metal ores and non-metal minerals.   Radioactive elements of interest include uranium, thorium and potassium.  These have always been present in the earth’s crust.
 
Radiation is actually widespread in our environment.  It comes from sources outside the earth’s atmosphere (cosmic radiation), rocks and soils, and from building materials such as bricks, mortar, concrete and tiles.  It also comes from the food and drinks we consume, and from man-made sources such as dental and chest X-rays.
 
NORMs remain with residue, but are in very low levels and detailed monitoring has shown that these do not pose a risk to those working within the residue operations or to anyone outside of our operations.
 
In Australia, the average annual dose received from natural background radiation is approximately 1.5–2 mSv.  In some parts of the world, this figure may be as high as 200 mSv per year*. (*Source – ARPANSA website,  http://www.arpansa.gov.au/RadiationProtection/Factsheets).
 
The acceptable dose limit for radiation workers is 20 mSv (above background) in a single year or 100 mSv (total) over a period of five consecutive years.  For members of the public, the incremental (above background) acceptable dose limit is 1 mSv per year. 
 
Alcoa has been monitoring radiation levels in bauxite and bauxite residue for more than 25 years.  This has involved comprehensive monitoring of air, water and soil, and has included both fixed position (area) monitoring and personal sampling of members of the workforce who spend most of their time working on the residue surface.  Results documented in scientific reports, and have been provided to employees and relevant government agencies.  Sampling equipment, methods and techniques have been endorsed by relevant statutory bodies such as the Radiological Council of WA and the Department of Industry and Resources.
 
Exposures have been comprehensively studied and all levels have been shown to be below the limits prescribed for the public (1mSv per year).