The application of the requirements for naturally occurring radioactive material has practical impacts for all mining and processing operations
This is an excerpt from a paper that was presented at Minesafe International 2017, which was held in Perth from 1-2 May.
The international standards for the management of naturally occurring radioactivity in natural materials are complex and sometimes contradictory and have the potential to result in wide-ranging impacts in many mining and minerals processing operations.
The standards are developed by the International Atomic Energy Agency (IAEA) and are generally adopted in their entirety around the world in national laws and regulations. The IAEA framework for managing naturally occurring radioactive material (NORM) is based on a logical graded approach to regulation that aims to ensure that the risks of radiation remain in perspective and that controls are commensurate with the actual magnitude of the risk. However, at a practical level, the application of the NORM standards is generally simplified, and a criterion is used that is based on the absolute concentration of radionuclides in a material. This is generally applied irrespective of the risk.
There are consequences of this simplification. The most important is that it undermines attempts to ensure that radiological hazards remain in perspective with other health, safety and environmental hazards and risks. In practice, the simplification of the standards leads to additional and unnecessary project and operational costs or operating constraints in licences. It also results in heightened regulatory and public scrutiny.
This article provides an overview of the IAEA NORM standards and looks at how they are applied in radiation protection legislation in Australia and other countries. The article also provides examples of where application of the simplified approach results in significant problems.
Naturally occurring radioactivity is ubiquitous. In all mining and minerals processing operations, naturally occurring radioactivity exists through the presence of low levels of naturally occurring uranium and thorium. The concentration of the uranium and thorium varies depending upon the mineralogy of the deposit and the processes used to produce the final products.
Material containing naturally occurring radioactivity is known as NORM (naturally occurring radioactive material), and in recent years there has been increasing requirements for the management and control of the potential radiological hazards of NORM to both people and the environment.
Compared to other product contaminants, materials with radioactivity tend to carry a higher level of scrutiny and regulatory concern. In some cases, the presence of radionuclides in any quantities attracts unwarranted significant public concern and adverse media publicity. This is usually irrespective of the actual radiological risk.
Naturally occurring background radiation is variable and causes radiation exposure to people everywhere. Exposures result in a ‘dose’, which is a standardised means of measuring the impacts to people, taking into account different chemical, biological and mechanical aspects of the exposure. ‘Dose’ is measured in sieverts (Sv), and people all around the world generally receive on average two to three millisieverts (mSv) per year from natural background radiation, although this can be one or two orders of magnitude higher in some areas.
For mining and minerals processing, radioactivity and radioactive materials are always present, and appropriate management and regulation that is commensurate with the actual risk is important. This avoids over-regulation due to perception.
International approach to naturally occurring radioactive material
Around the world, the recognised approach to managing NORM is based on published guidance and standards from the IAEA. The IAEA outlines a framework that is based on a graded approach to regulation, which is dependent upon the actual risk and includes cut-off concentrations for radioactivity in materials, above which investigation of the material is required.
For materials to be classified as radioactive, and therefore potentially subject to regulation, the following definitions are provided in the IAEA safety glossary (IAEA, 2007):
- a material is defined as ‘radioactive’ when it is ‘designated in national law or by a regulatory body as being subject to regulatory control because of its radioactivity’
- NORM is defined as material (irrespective of whether it is processed or not) ‘that contains no significant amounts of radionuclides other than naturally occurring radionuclides’
- for naturally occurring radioactive material, moderate quantities of materials containing natural uranium (Unat) and thorium (Thnat) greater than 1 Bq/g are defined as radioactive material.
Note that Bq/g is an abbreviation for ‘becquerels per gram’, which is a measure of the amount of radioactive per mass of material. Unat and Thnat are abbreviations for naturally occurring uranium and thorium respectively, with their decay products in secular equilibrium. In a practical sense, 1 Bq/g of Unat is equivalent to approximately 80 ppmU and 1 Bq/g of Thnat is equivalent to approximately 240 ppmTh.
The IAEA (2007) advises that in all cases, a ‘graded approach to regulation of NORM’ should occur. Specifically, controls for radiation protection should be commensurate with the actual radiological risk. In practice, this is a complex and sometimes legally difficult requirement to implement because there are many factors that need to be taken into account in the risk assessment.
To assist in the regulation and management of NORM, the IAEA (2004) developed the concepts of ‘exclusion’, ‘exemption’ and ‘clearance’ of materials to assist national regulatory authorities. The summarised definitions are as follows:
- ‘Exclusion’ refers to radionuclide concentrations being below the trigger level and therefore not subject to regulation. This refers to material that is ‘…unamenable to control’ and includes cosmic radiation, natural levels of radon and radiation from K40.
- ‘Exemption’ refers to materials that are above the trigger level but where it can be shown that the impacts of the material do not warrant radiological control and that the ‘risks [are] so low as to not warrant regulatory control or provide any net benefit’. Exemption can only be determined and granted by the appropriate regulatory authority, with automatic exemption for moderate quantities of materials <1 Bq/g (Unat or Thnat).
- ‘Clearance’ refers to materials that are above the trigger levels and are already being used and for which it can be shown the impacts do not warrant regulatory control or further regulatory control. This is referred to as ‘…removal of material from further control…’ and is applicable, for example, for equipment, material, residues and wastes.
In summary, the IAEA guidance says that once a material containing naturally occurring radioactivity exceeds the trigger level of 1 Bq/g, an assessment should be undertaken to understand the actual risk and then the material should be managed accordingly.
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Regulation of naturally occurring radioactive material in Australia
The IAEA safety guides and standards for radiation protection are almost universally adopted in countries around the world and end up in national legislation, and this is also true for Australia.
Australian states and territories are responsible for developing and implementing regulations for activities and actions within their specific jurisdiction, including for radiation protection. Australia aims for a
nationally uniform system of laws and regulations; however, this is generally not the case in practice, with requirements differing from jurisdiction to jurisdiction. Care needs to be taken to ensure that the correct laws and regulations are being followed.
For radiation protection and NORM, an important national body is the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), which is the Australian Government’s primary authority on radiation protection and nuclear safety.
ARPANSA regulates federal entities that use radiation or are involved in nuclear activities. It also undertakes research and provides radiation protection services. Key functions of ARPANSA are to align Australia with recognised international practices and promote and encourage national uniformity.
To fulfil this latter function, ARPANSA publishes a series of documents that are part of its Radiation Protection Series.
A key ARPANSA NORM-related document is the ‘Safety Guide for the Management of Naturally Occurring Radioactive Material (NORM)’ (ARPANSA, 2008). This document essentially follows the guidance provided by the IAEA.
- The document describes the following:
- identification of industries where NORM radiation protection issues may arise
- radiological issues in NORM management
- regulatory issues in NORM management
- operational issues and development of a NORM management plan
- remediation of legacy sites.
The document also provides a practical set of further guidance for industries with NORM, including:
- oil and gas production
- the bauxite and aluminium industry
- the phosphate industry.
ARPANSA has advised that the document is being updated to include metal extraction, coal mining, electricity generation and the iron and steel industries.
State and territory-based regulation in Australia
The regulation of NORM across different states and territories varies. Individual jurisdictions have ultimate responsibility for regulation and have their own versions of radiation protection and control acts with associated regulations. The versions tend to cover similar aspects, but focus on the particular issues present in that jurisdiction. Generally, the versions refer to national codes of practice and guidance documents (such as those produced by ARPANSA), but this is not always the case, with some jurisdictions writing their own guidance documents.
In practice, NORM management generally consists of:
- licence requirements
- reference to the national standards (ARPANSA codes and guides)
- identifying the prescribed activities
- establishing dose limits
- certification of equipment and for use
- development and approval of management plans.
For NORM-related operations, a NORM management plan is required as part of project approval, licencing or permitting. These documents cover aspects such as:
- overview of the project
- identification of potential sources of health impacts on workers and the public and any radiological impacts to the environment
- management of the impact on workers, members of the public and the environment
- remediation and close-out requirements for operational sites
- non-radiological issues.
Naturally occurring radioactive material management in practice
Radiation generally attracts unnecessary scrutiny and regulatory concern. There are many cases where the presence of radionuclides (and radiation), in whatever quantities, has resulted in public concern and negative media publicity. This is despite the fact that almost every substance contains naturally occurring quantities of radionuclides.
At a practical level, the IAEA guidance of 1 Bq/g results in materials containing naturally occurring uranium and thorium being classified as ‘radioactive’ and therefore subject to regulation.
The 1 Bq/g requirement also applies to all of the naturally occurring radionuclide decay products. Table 1 gives a comparison of the mass concentrations of long-lived radionuclides in the uranium (U238) decay chain for comparison.
The application of the requirements for NORM has practical impacts for all mining and processing operations.
Perceptions about low levels of radioactivity vary, and it is important that any radiation protection system does not re-enforce the wrong perceptions. Unfortunately, the system in practice seems to have encouraged the following incorrect perceptions for NORM:
- radiation is dangerous at low levels
- the 1 Bq/g criterion is a limit
- when a limit is exceeded, the situation is unsafe
- when a material is defined as radioactive, it needs to be controlled, therefore it is dangerous
- a material from a licenced radioactive facility must be dangerous.
An example of where systems reinforce the wrong perception can be seen in the Australian Environmental Protection and Biodiversity Conservation Act, which requires operations handling material exceeding 1 Bq/g to be referred for assessment as a ‘nuclear action’. The impression therefore is that NORM is as dangerous as nuclear material.
Application of the system
A major concern for operators is whether their materials are actually dangerous enough to require such a seemingly high level of scrutiny and management.
A material containing 0.9 Bq/g (eg naturally occurring uranium at a mass concentration of approximately 70 ppm) would be considered to be automatically exempt from regulation, while a material containing 1.1 Bq/g (for example uranium at a mass concentration of 90 ppm) would be defined as a radioactive material and therefore subject to regulatory consideration.
An organisation is likely to invest significant sums of money to ‘get the radionuclides below the limit’. However, this may be easier said than done, because radionuclides would exist in the materials in only trace amounts (as seen in Table 1).
The capacity chasm
Uranium, mineral sands and some rare earth producers maintain expertise in radiation protection. Within these operations, the radiation protection culture is mature. Controls are built into designs of processes as well as into management systems. The operations employ radiation protection specialists.
On the other hand, the ‘non-radioactives’ tend to have a lack of internal expertise on radiation protection. There is a heavy reliance on external advice and assistance. Decisions are more likely to be made based on absolutes, such as being able to get below the limit, rather than from a risk-management perspective, such as understanding potential doses and managing them. These organisations are much more conservative and wary when it comes to radiation, which is based on a genuine fear of the physical and environmental effects of radioactivity through to its potential impact on the business image and the image of its products.
The presence of radioactivity or radioactive materials can have the unintended consequence of diverting attention from other potential high risks that could result in a higher level of harm.
For any operation, there are a range of risks and hazards that need to be controlled and managed, both acute exposure hazards (such as rockfalls and vehicle accidents) and chronic exposure hazards (such as noise and dust). Maintaining radiation and all of these other hazards in perspective is important for optimising the overall safety and environmental protection of the project.
The overemphasis on radiation for intended or unintended reasons means that the perspective is difficult to maintain. Lack of knowledge, difficult regulations, complex requirements
and perceptions usually mean that any radiation hazard requires additional attention.
For example, airborne dust monitoring may identify elevated radionuclide concentrations in air, and the cause may be linked to the radionuclide concentration in the source of the dust. One solution may be to limit the radionuclide content of the dust source. However, attention must remain on the overall situation and the fact that dust is present and it is more likely that the elevated radionuclides in the air is due to more dust in the air as a result of inadequate ventilation.
The contradiction is that that the low levels of radioactivity that exist in some material can be seen to be the most important aspect of the material, resulting in an overemphasis on one risk and the masking of other potential risks.
The IAEA framework for radiation protection of materials containing low levels of naturally occurring radioactivity is complex and unclear. This promotes uncertainty for all parties and, in practice, leads to the application of the simplest framework.
While the intent of the IAEA framework is to have a graded approach to the regulation of such materials, in practice, most regulatory systems are based on the simple requirement of materials containing more than 1 Bq/g. This is regardless of the actual risk of the material.
Radiation is an emotive subject and it is recommended that there is more emphasis in national guidance on providing clearer standards to avoid perception-driven regulation. To do this requires additional education and information and consideration of the practical implementation of international and national guidance.
A key factor is that radiation protection professionals need to ensure that the systems for control are better understood by proponents, regulators and legislators in order to ensure their appropriate application.
Feature photo: The Vienna International Centre, which houses the International Atomic Energy Agency. Photo by Rodolfo Quevenco/IAEA. Used under CC BY-SA 2.0.
Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), 2008. Safety guide for the management of naturally occurring radioactive material (NORM), Radiation Protection Series no. 15.
International Atomic Energy Agency (IAEA), 2004. Application of the concepts of exclusion, exemption and clearance, Safety Guide Series No. RS-G-1.7.
International Atomic Energy Agency (IAEA), 2007. IAEA safety glossary: terminology used in nuclear safety and radiation protection: 2007 edition.