Naturally occurring radioactive material

Naturally occurring radioactive materials (NORM) and technologically enhanced naturally occurring radioactive materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium-40 (a long-lived beta emitter that is part of natural potassium on earth) and any of the products of the decay chains of the former two, such as radium and radon. Produced water discharges and spills are a good example of entering NORMs into the surrounding environment.

Natural radioactive elements are present in very low concentrations in Earth's crust, and are brought to the surface through human activities such as oil and gas exploration, drilling for geothermal energy or mining, and through natural processes like leakage of radon gas to the atmosphere or through dissolution in ground water. Another example of TENORM is coal ash produced from coal burning in power plants. If radioactivity is much higher than background level, handling TENORM may cause problems in many industries and transportation. If a mineral has naturally occurring radioactive material present, the tailings may have a higher concentration of radioactive substance than the ore had. By mass perhaps the biggest example of such material is phosphogypsum where radium-sulfate is left with the gypsum that results from treating apatite with sulfuric acid to extract phosphoric acid. Another example is in rare earth-mining where ores such as monazite may contain thorium and its decay products which are subsequently found enriched in the tailings.