Naturally-occurring radioactive material (NORM) is the term used to describe materials that contain radionuclides that exist in the natural environment. Of particular interest are the long-lived radioactive elements uranium and thorium, and any of their radioactive decay products, such as radium and radon, elements that have always been present in the earth’s crust and within the tissues of all living species.
Although the concentration of NORM in most natural substances is low, almost any operation in which any material is extracted from the earth and processed can concentrate NORM in product, by-product, residue or waste streams.
Waste containing naturally occurring radionuclides, may originate from the mining or processing of ores and minerals, including:
- phosphate minerals
- mineral sands
- some gold bearing rocks
In some cases NORM from mining and processing of mineral ores has to be managed as radioactive waste—for example, the processing of phosphate ore or oil and gas production.
Disposal of naturally occurring radioactive material
A number of disposal options exist that may be appropriate for NORM wastes, depending on its waste classification level, including:
- near surface burial
- disposal to municipal tips or landfill
- disposal into underground mines as cemented backfill
- injection into old oil wells slated for abandonment and plugging with some form of encapsulation (such as cement grout)
- disposal into mine waste rock dumps, smelter slag dumps, mine tailings dams or power plant ash ponds (this option, however, may only be an interim measure in some cases).
Except in unusual circumstances, storage of NORM wastes/residues should not be considered as a long term management option, because the very long half-lives would not lead to significant reduction in exposures over typical storage timeframes.
The choice of an appropriate approach to management and disposal of NORM wastes can depend on factors such as radionuclide concentrations in the waste, the physical form of the waste (solid, liquid or gas) and the chemical form of the waste. Environmental impact can be limited by reducing the mobility of the waste. This can be achieved through solidification of liquids and/or the use of engineered barriers.
Regulation of naturally occurring radioactive material
The regulatory approach to NORM issues within Australia is guided by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). The Commonwealth and each state and territory government has a regulatory system for radiation protection, including the use of radioactive materials. In each jurisdiction the regulations include exemption limits on, for example, the total activity and activity concentration of radioactive material to be regulated.
Waste rock, process tailings, and products containing elevated concentrations of naturally occurring radionuclides are covered by the ARPANSA Code of Practice and Safety Guide Radiation Protection and Radioactive Waste Management in Mining and Mineral Processing (2005).
The Code of practice for the near-surface disposal of radioactive waste in Australia (NHRMC, 1992) (currently under revision) is applicable to bulk NORM residue disposal. Those seeking information on NORM can also consult the ARPANSA Safety Guide for Management of Naturally Occurring Radioactive Material (NORM) (2008).
The facility to be established under the National Radioactive Waste Management Act 2012 is for the express purpose of managing waste arising from the beneficial medical, industrial and research uses of radioactive material in Australia. As such, the facility is not intended to manage NORM wastes.
For more information about naturally occurring radioactive material see ARPANSA and State/Territory regulators.