Workers in Industrial Processes Involving NORM

What are the examples of activities associated with NORM?

The following industrial activities associated with NORM are, or may be, subject to Regulations.

• Mining and processing of uranium ore.
• Extraction of rare earth elements.
• Production and use of thorium and its compounds.
• Production of niobium and ferro-niobium.
• Mining of ores other than uranium ore.
• Production of oil and gas.
• Manufacture of titanium dioxide pigments.
• Activities in the phosphate industry.
• Activities in the zircon and zirconia industries.
• Production of tin, copper, aluminium, zinc, lead, and iron and steel.
• Combustion of coal.
• Water treatment.

What do I need to know?

Workers involved in the industrial processes involving NORM are occupationally exposed to radiation. Not all industrial processess produce NORM. The volumes and concentrations of NORM vary according to the natural abundance of radionuclides in the materials that are employed or treated. Current exposures to NORM in industrial processes are low; however regulations, controls and monitoring are required to optimize the radiation exposures.

According to the GSR Part 3, occupational exposure due to natural sources is, in general, subject to the requirements for existing exposure situations. In the case of occupational exposure due to radionuclides of natural origin in materials other than these everyday commodities and due to radionuclides in residues in the environment, the applicable requirements depend on the radionuclide activity concentrations, as follows:

• If, in any process material, the activity concentration of any radionuclide in the ²³⁸U decay series or the ²³²Th decay series exceeds 1 Bq/g, or if the activity concentration of ⁴⁰K exceeds 10 Bq/g, the industrial activity is regarded as a practice and the requirements for planned exposure situations apply.
• If, in every process material, the activity concentrations of all radionuclides in the ²³⁸U decay series and the ²³²Th decay series are 1 Bq/g or less and the activity concentration of ⁴⁰K is 10 Bq/g or less, the material is not regarded as naturally occurring radioactive material, the industrial activity is not regarded as a practice and the requirements for existing exposure situations apply.

What is the possible exposure?

The exposure pathways to workers that are most likely to necessitate consideration are those involving external exposure to gamma radiation emitted from process material and internal exposure via the inhalation of radionuclides in dust, as follows:

• The main radionuclides of natural origin contributing to gamma exposure are ²¹⁴Pb and ²¹⁴Bi from the ²³⁸U decay series, and ²²⁸Ac, ²¹²Pb and ²⁰⁸Tl from the ²³²Th decay series. The highest gamma energy (2614 keV) is associated with ²⁰⁸Tl. Exposure to gamma radiation arises mainly from accumulations of mineral concentrates or residues. Dose rates are generally highest near process tanks, piping, filters and large stockpiles of material.
• Airborne dust particles arise from the resuspension of contamination on floors and other surfaces, from releases from processing operations and from the conveying of minerals. For inhalation of such particles by workers in industrial activities involving naturally occurring radioactive material, exposure due to radionuclides in the ²³⁸U decay series and the ²³²Th decay series may be of concern for the purposes of radiation protection.

Consideration of internal exposure via the inhalation of ²²²Rn emitted from process material — leading to exposure due to its short-lived progeny — may be necessary in some activities involving minerals and raw materials. Exposure due to ²²⁰Rn and its progeny is not normally of concern because the half-life of ²²⁰Rn is much shorter than that of ²²²Rn. Attention should be given to ²²⁰Rn in certain workplaces involving minerals with a high ²³²Th content, such as monazite. In such workplaces, it is likely that the exposure would, in any case, be controlled as a planned exposure situation rather than as an existing exposure situation because of the need to control exposure due to other radionuclides in the ²³²Th decay series.

Internal exposure of workers via ingestion is unlikely to require consideration under normal operational circumstances.

The annual effective doses received by workers in industrial activities involving naturally occurring radioactive material are often low, even when the concentrations of radionuclides in the ²³⁸U decay series and the ²³²Th decay series are significantly higher than 1 Bq/g.

Who is responsible for your protection and safety?

The person or organization responsible for any facility or activity that gives rise to radiation risks shall have the prime responsibility for protection and safety, which cannot be delegated.

Organisations/employers are responsible for:

• Devising, implementing, and regularly reviewing their Radiation Protection Programme.
• Regulatory compliance.
• Development a training programme that provides the appropriate level of training and information specific to the worker`s job assignments and also general radiation protection information.
• Induction and ongoing training of workers, including contractors.
• Appropriate dosimetry arragements.
• Record keeping.

What are your responsibilities to the employer and the management of the facility?

Workers are responsible for:

• Providing to the employer (and registrant or licensee, where appropriate) information on work history relevant to developing an effective protection and safety programme for the worker (and others);
• Communicating perspectives on job specific radiation risks gained from education and training, and otherwise cooperating with regard to developing and executing an effective protection and safety programme.
• Following radiation protection practices specified in local rules, procedures and in the Radiation Protection Programmme, including the proper use of monitoring and personal protective equipment as described in those rules and procedures.
• Complying with legitimate instructions of the employer or designated Radiation Protection Officer;
• Participation in radiation protection training.
• Reporting to the employer or designated Radiation Protection Officer identified circumstances jeopardizing protection and safety of the worker or others.
• Abstaining from any wilful action that could put the worker or others in situations not in compliance with the requirements for protection and safety.

What is a Radiation Protection Programme?

The general objective of the radiation protection programme is to fulfil the management’s responsibility for protection and safety through the adoption of management structures, policies, procedures and organizational arrangements that are commensurate with the nature and extent of the risks. The radiation protection programme should cover all the main elements contributing to protection and safety. The radiation protection programme could relate to all phases of a practice or to the lifetime of a facility (i.e., from design through commissioning and operation or process control to decommissioning).

Radiation protection is only one element in ensuring the overall health and safety of workers. The radiation protection programme should be established and managed in close cooperation with those responsible for other areas of health and safety such as industrial hygiene, industrial safety and fire safety.

What are dose limits?

The GSR Part 3 requires annual limits for public and occupational exposure to ionising radiation: 1 mSv for the members of the public and 20 mSv for workers who are occupationally exposed. Despite this, there are different definitions of who is “occupationally exposed” and who should wear personal dosimeters.

References

• Fundamental Safety Principles, IAEA Safety Standards Series No. SF-1, IAEA, Vienna (2006).
• Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, IAEA Safety Standards Series No. GSR Part 3, IAEA, Vienna (2014).
• Occupational Radiation Protection, IAEA Safety Standards Series No. GSG-7, IAEA, Vienna (2018)