Employers who work with materials that contain small but, from a radiation protection perspective, significant amounts of naturally occurring radioactive substances are required, under the Ionising Radiations Regulations 1999 (IRR99), to take action to restrict radiation exposure of their employees and other persons who may be affected by their work with such materials.
Some processes with a recognised potential to cause significant radiation exposure occur in the oil and gas industry where naturally occurring radium and its daughters, may build up over time as scale in pipes and vessels. Some metal smelting applications may also cause exposure to NORM; here naturally occurring radionuclides may concentrate in foundry slag or may be present in radiologically significant concentrations in refractory sands which contain low concentrations of natural uranium and thorium, . Exposure arising from work with materials that contain NORM, can sometimes come directly from the raw materials themselves , but more commonly results from their processing. The IRR99 apply where such processes could cause employees or other persons to receive an annual dose in excess of 1 mSv and so employers must determine in the health and safety risk assessment, required by the Management of Health and Safety at Work Regulations 1999, whether such exposures are likely and, if so, take the necessary steps to comply with the IRR99 .