Industrial practices involving exposure to natural radiation - NORM

In this context, naturally occurring radioactive material refers to uranium and thorium with their decay products as well as potassium-40. Other radioactive substances are also present in small quantities in nature, but the radiation exposure caused by them is usually insignificant.

When materials containing natural radioactive substances are utilized in industrial processes, the equilibrium of natural radioactive substances may change and they may accumulate in, for example, waste, sludge, water, by-products, pipelines or filters. These are internationally known as Naturally Occurring Radioactive Material, NORM (IAEA Safety Glossary 2018). In Finnish legislation, the term NORM is not used.

Industrial practices involving exposure to natural radiation exploit naturally occurring soil, rock or other materials occurring in nature or the materials brought about by the use of the aforementioned. Examples of such industrial activities involving exposure to natural radiation are mining and underground excavation, metal ores enrichment, the operation and maintenance of coal and peat power plants and groundwater treatment. For example, various heat-resistant mineral-based materials or materials containing zircon may also contain natural radionuclides. The handling of such materials may result in exposure to natural radiation.

Radioactive materials that occur in nature which are accumulated in materials can cause either internal exposure to the population and workers through respiratory air and food or external exposure from penetrating gamma radiation. In industrial practices involving exposure to natural radiation, radioactive materials that occur in nature do not pose an immediate radiation hazard, but the exposures are typically small. However, exposure to natural radiation must be taken into account in radiation protection if necessary, as ionizing radiation may cause health hazards in the long term. The objective of radiation protection is to keep the exposure of employees and the general public as low as reasonably achievable through practical measures.

Under the Radiation Act, practices that cause exposure to natural radiation give rise to obligations for the operator, such as the obligation to investigate radiation exposure. STUK supervises compliance with the Radiation Act.

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