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Naturally Occurring Radioactive Material and Technically Enhanced NORM

Most human activity exposes the body to radiation in one form or another. Background radiation, which is present in terrestrial, cosmic, and cosmogenic sources, is always around us.1Thomas Crampton, May 24, 2001, “Flying on Top of the World: A Radiation Risk,” The New York Times, [OHC1] The sun’s rays contain radiation, and Naturally Occurring Radioactive Material (NORM) are found throughout the environment. NORM primarily contains uranium, radium, thorium and potassium of natural origins and is found throughout the oil and gas industry.

Technologically Enhanced NORM or TENORM means that the radiological, physical, and chemical properties of the NORM have been concentrated or further altered by having been processed, beneficiated, or disturbed in a way that increases the potential for human and/or environmental exposures. TENORM is generated by many industries such as wastewater treatment, mining, and energy production including coal combustion, oil and gas production and natural gas processing.2EPA, 2023, February 15, Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM),

Radiation in TENORM includes the radioactive particles Radium-226 (Ra-226), Radium-228 (Ra-228), Lead-210 (Pb-210), Polonium-210 (Po-210) and Radon generated from the decay of unstable NORM particles. NORM and TENORM are found in produced water, precipitate scale, sludge, and contaminated equipment.3EPA, 2022, July 14, Radioactive Waste Material From Oil and Gas Drilling, This means that anyone on an oil and gas site can be exposed to NORM or TENORM at various stages of hydrocarbon production.      

Additionally, Radon is gaseous under standard conditions and easily inhaled. It can move up from the subsurface into buildings through cracks and openings in floors and crawlspaces that are in contact with the ground. Overtime it can accumulate in low areas and pose a serious health hazard; radon gas inhalation is the second leading cause of lung cancer after smoking.4Colorado Dept of Public Health & Environment, Radon, accessed April 15, 2023, Radon can also dissolve in groundwater, and when well water is drawn into homes or facilities it may release, collect in low places, and expose inhabitants to increased radiation through inhalation.

Currently, there are no specific federal regulations for NORM or TENORM. States regulate both in various programs which may involve radiological, public health and environmental agencies along with the state oil and gas commission. In Canada NORM and TENORM is regulated by the provincial and territorial governments each having its own specific regulations.5Canadian Nuclear Safety Commission, 2012, October 10, Naturally Occurring Radioactive Material, In 2022, STRONGER, The State Review of Oil and Natural Gas Environmental Regulations, published a document with recommendations for the regulation of NORM and TENORM. Major recommendations from the report are for states to identify consistent definitions of NORM and TENORM, to develop regulations that focus on defining action levels, licensing and permitting of disposal facilities, and building worker protection standards. Additional aspects would include establishing remediation criteria, identifying disposal options, and conducting surveys to identify NORM and TENORM6State Review of Oil & Gas Environmental Regulations, 2017, Naturally Occurring Radioactive Materials,, accessed April 15, 2023 from


Oil and gas operations concentrate NORM, which can raise the radiation levels of various types of equipment.

Different materials can stop different kinds of radiation. Courtesy Alpheus Media.


Different materials can stop different kinds of radiation.

Radiation occur in the form of alpha particles, beta particles and gamma rays. The particles are stopped by thin layers of plastic or metal, but gamma rays pass through many materials including the human body. Those who encounter TENORM should wear protective clothing and respirators to limit radiation exposure. However, the best defense against radiation is knowledge. A Geiger counter measures total radiation in a particular area of screening, but an approach that provides personal radiation detectors to everyone who may encounter TENORM allows every individual to monitor their exposure in real time. This empowers every individual to make the most informed decision about her or his own exposure.

One of our experts explains the finer details of NORM sources and monitoring and how to maintain a safe working environment for oil and gas sites.


Naturally Occurring Radioactive Material in Oil & Gas Operations – Mike Arthur – Penn State

Most human activity exposes the body to radiation in one form or another whether from the sun shining overhead or from elements within earth. This is referred to as naturally occurring radioactive material or NORM. Lifestyle and occupation can change one’s exposure rates to NORM. Also, industrial activities like mining and processing can concentrate naturally occurring radioactive material in the environment. We call this technically enhanced NORM or TENORM. It is critical for personnel in the petroleum industry to understand how they might be exposed to TENORM and how to mitigate the risks.

The likelihood of exposure to non-routine radiation sources in oil fields and refineries depends on both the region and source of hydrocarbons. For example, the relatively geologically young oil sources and reservoirs in California are not highly radioactive in comparison to the much older rocks and reservoirs of the Appalachian basin. There are different types of radiation and different ways of being exposed to it. The two most common elements composing NORM from geological sources are uranium, primarily uranium 238, and radium, typically, radium 226.

Radiogenic isotopes of some other common elements such as thorium, potassium and lead also emit measurable amounts of radiation. Radiation emitted by these elements occurs in the form of alpha particles, beta particles or gamma rays depending on the isotope. Because they are particles, alpha and beta radiation is easily stopped by thin layers of plastic or metal. Gamma rays, on the other hand, are high-intensity waves of electromagnetic radiation. These waves easily pass through many materials. Gamma radiation is considered an external hazard to living tissue and requires containment with thick layers of lead.

Appropriate protective clothing and respirators can provide protection from alpha and beta particles, but it would not prevent exposure to gamma rays. Alpha and beta decay is almost always accompanied by gamma decay. Gamma rays are electromagnetic waves with very high frequencies and energy, so protective clothing can minimize total radiation exposure, but it won’t block more harmful gamma radiation. Hydrocarbon production can concentrate NORM, as large quantities of materials from beneath earth’s surface are collected, transported and stored. This means workers can be exposed to radiation in a variety of ways and at different stages of hydrocarbon production. Radioactive uranium and thorium may be found in formations above and within hydrocarbon reservoirs and may be found in well cuttings brought to the surface. This is particularly problematic in unconventional shale wells with long horizontals that penetrate hydrocarbon bearing shales with high uranium and radium contents.

Fluids are another area of risk. Uranium and thorium are generally sparsely soluble in fluids, but radium mobilizes with produced water and hydrocarbons and can precipitate as a radioactive mineral scale in well casing, pipelines and tanks. Radium can be filtered from solution using clay cakes or precipitated as a component of carbonate minerals. Radioactive gas can contaminate the air. Radon, a gas, migrates with natural gas, but because of its short half life of 3.8 days is generally less of a problem. Radon can, however, build up in enclosed spaces.

Exposure to radiation from TENORM has two kinds of effects, acute and delayed. High levels of radiation immediately cause certain blood chemistry changes, nausea, fatigue, cataracts and a skin effect resembling sun burn. Long-term exposure to uranium has been linked to cancer, and kidney and liver damage. Radium mimics calcium in the body, increasing the risk of bone and blood cancers. The Environmental Protection Agency mandates maximum contaminate levels for uranium and radium in drinking water. However, these levels differ for waste water and landfill disposal of sludges and other solid wastes. The allowable levels are much higher for waste water and sludges taken to landfills. That’s why appropriate safety procedures must be followed when handling these materials.

For oil field workers or inspectors, the most common exposure to radiation will be through pipes, tanks, logging tools, produced water and cuttings. The key to avoiding radiation exposure is to know when it’s there. This is done through monitoring. There are several ways to monitor radiation levels. Probing near the surface with an uncompensated Geiger-Muller tube will measure alpha and beta particles released by decaying elements. Gamma ray screening can be accomplished with a sodium iodide base detector. Although gamma rays have no charge and thus no detector is directly sensitive to them, gamma rays do interact with matter and produce charged particles, typically electrons.

The electrons in a sodium iodide crystal scintillate to produce an amount of light. These light pulses are converted to electrical pulses in a photo multiplier tube. Although these detectors sometimes overestimate the gamma dose rates, these crystals are particularly useful because charged particles produce an amount of light directly proportional to their energy. A compensated Geiger-Muller tube provides a slower measurement but a more accurate indication of present radiation. This gas-filled tube scintillates when a charged particle enters the tube. This type of counter measures total radiation and does not distinguish particles types. In recent years, technology has advanced to the point that workers can wear a small device that measures total radiation levels. Personal radiation detectors or PRDs are relatively inexpensive and typically accurate to plus or minus 15%. Workers who may be exposed to radiation should be outfitted with these devices.

Petroleum production carries with it many safety risks. That’s why personnel must be educated, procedures must be followed and appropriate technology must be employed to ensure a safe working environment.

Images: “Trinity Site Fence” by marsupialrobot licensed under CC BY NC ND 2.0; “Graphic” by Coleman Tharpe