Radiological Protection from Naturally Occurring Radioactive Material (NORM) in Industrial Processes

The Dutch Radiation Protection Society (NVS) department of Industrial Radiation Protection requested several members working in the “NORM arena” to comment on the recent ICRP draft “Radiological Protection from Naturally Occurring Radioactive Materials (NORM) in Industrial Processes”. It turned out that several of those NVS members are involved in various bodies that also take care of commenting on the ICRP draft. In this respect these comments can be viewed as a ‘partly NVS’ comment but it does not cover the ‘averaged’ opinion of the NVS.

The review of the draft ICRP document has been carried out from a practical point of view.  NORM is an international phenomenon and inconsistencies in NORM management will influence the international trade of raw and/or partly processed resources contaminated with Naturally Occurring Radionuclides. In this respect it is hoped that the ICRP provides a ground laying document, on which a consistent NORM management – both from a regulatory and industrial point of view – may be founded. Our comments are provided along the following lines:

• Appreciation of the “ICRP NORM document” (thumbs up)
• Ambiguity in the terminology used
• Hints of missing information
• Suggestions for improvement (of the text)
• Typographical errors

The received NVS comments appreciate the following characteristics of the draft document (‘thumbs up’):

• … not using the term ‘NORM industries’ (“the main products of the car industry are cars, what would be the main product of the NORM industry”?) and using “industries involving NORM”. Only on line 115 there is a suggestion of NORM industries (viz. ‘NORM industrial activities”, see comments below)
• … that “the Commission recommends the use of an integrated approach for the management of radiation and other hazards.” A good risk comparison paper q. document would be very helpful in this respect (wishful thinking): line 1181 “… the conclusion proper balance between the different hazards …”.
• … that “NORM is not considered in splendid isolation”, but that industrial processes may be associated with multiple hazards. Radiation protection remains a very specialized skill within the full HSE spectrum of hazards. However, for industries in general, radiation protection should be included within the HSE organization “it is just another hazard to be considered”.
• … that the Commission proposes “a graded approach, commensurate to the level of the risk as well as other considerations such as economic and societal, is appropriate and particularly relevant for industries involving NORM due to economic importance of industries, large volumes of residues and wastes and limited options for management, moderate level of doses, and potentially high cost of regulation in relation to reduction in exposure.” and advocates pragmatism.
• … that “NORM associated with industrial processes is” considered as “an existing exposure …”, so it is not a practice deliberately exploiting q. using radioactivity.

The draft document is ambiguous in the use of some terminology or misses out some definitions or extra information:

• there is no appropriate definition of NORM. In some instances the document is referring to primordial (or secondary) terrestrial Naturally Occurring Radionuclides (NOR’s), while in other instances the document refers to materials (or process streams) contaminated with NOR’s (NORM). Disassembling both concepts - NORM and NOR’s - will lead to less confusion as often present in the open literature.
• furthermore, the term ‘NORM’ is a misnomer

-     ‘naturally occurring’ refers to the radionuclide's in the “material” (matrix) and not (necessarily) to the ‘material’ (a [by]product / residue / waste of a physical, chemical or thermal industrial process) itself

-     radionuclide’s of natural origin (NOR’s) are ubiquitous in our environment, it could be argued that consequently all natural resources or ‘materials’ are effectively NORM (scientific vs. regulatory point of view)

• the term ‘material’ (Oxford Dictionary: The matter from which a thing is or can be made) may also refer to process streams. In this respect the term ‘material’ – more or less referring to solid substances – is somewhat restricted and may be replaced by ‘substances’ (Oxford Dictionary: A particular kind of matter with uniform properties) that may include a (uniform) gaseous stream, liquid or particulate (solid) process streams, internal deposits or scale.

Another option may be the use of the term ‘matrix’ (cf. line 332). “… the physical and chemical matrices in which the radionuclides are incorporated…”. It can even be considered to redefine the acronym NORM as Naturally Occurring Radionuclide Matrix (NORM) and in this sense the terminology of “NORM materials” as often noted in the literature becomes correct.

The NVS is missing the following definitions and/or additional information

Line 291               “Details on these work activities are provided in Appendix 1.”

  There is no proper definition, what is meant by ‘work activities’.

Line 297/299      “5. Manufacture of titanium dioxide pigments.”/”7. The zircon and zirconia industries.”

                                 It is not only the manufacture that may lead to enhanced exposures. Enhanced radiation doses may already be contracted during the mining of mineral sands (especially the rutile and ilmenite components, but mineral sands also may contain monazite and ‘zircon’)

Line 298               “6. The phosphate processing industry.”

  Mining and beneficiation of phosphate rock may also lead to enhanced exposure.

Paragraph 81     For several industries it is essential to make a distinction between normal operation and maintenance activities. If no  open vessels or units are applied in the industrial process (e.g. gas/oil industry, geothermal heat production) the whole facility can more or less considered to be a ‘closed source’, where only external exposure pathway (for operational workers) may be relevant. Upon maintenance activities installations are opened up for entry (cleaning, change malfunctioning parts, etc.), where – dependent on the actual activities carried out – all exposure pathways are relevant. For maintenance activities the population of workers will be much wider as well, as workshop workers or third-party (contracted) workers must be included as well.

                                  Some fine tuning, when taking for instance samples from NOR-contaminated process streams during normal operations additional pathways may become relevant to include in dose assessment.

• This paragraph should mention “operational conditions” vs. “maintenance conditions” as well.

Paragraph 82     You promote realistic conditions. For external radiation during normal operations I always take the external radiation level (measured with suitable, explosion-proof [an additional hazard to consider] monitor at 1 m height and at 1 m from the surface of the unit/vessel/reactor) and assess the exposure time via an interview with operational workers. Especially to measure dose rates at 1 × 1 m may be suggested in your text, as still often the dose rate measured at the surface of the unit/vessel/reactor is used for dose assessments (to impress HSE management, or to force – in many cases unnecessary – HSE measures.

• consider providing minimal guidance (measure at approximately 1 m height and 1 m from the unit/vessel/reactor surface) to measure realistic external dose rates under normal operational conditions.

Paragraph 85     You suggest periodic review, but it is also very important to repeat such a review non-periodical in case of change of feedstock (origin), minor changes in the process, taking an additional well into a production, maturing of an oilfield (change in water cut or water breakthrough), etc.

• consider to include special cases for review.

The NVS suggest the following changes for (textual) improvement

Line 41                  insert “may”: Industries involving NORM may give rise to multiple hazards …

Line 53                  replace “An integrated approach to NORM processes …” by “An integrated approach to processes involving Naturally Occurring Radionuclide’s (NOR’s) …”

Line 56                  replace “…a graded response to the magnitude of the hazards … ” to “a graded response to the magnitude of all relevant hazards …”

Line 115               replace “NORM industrial activities are controllable, …” by “Industrial activities involving Naturally Occurring Radionuclide’s are controllable, ...”

Line 136               replace “… naturally radionuclides …” by “… Naturally Occurring Radionuclides (NOR’s) …”

Line 304               insert “(heat)”: 11. Geothermal (heat) energy production.

Line 319               “(23) Work with NORM can give …“

                                This sentence starts a bit fuzzy. What is meant by “work with NORM”?

Line 323               replace: “…the way NORM occurs in the workplace, …” by “… the way NORM appears in the workplace, …”

Line 370               insert “consequently”: “These estimates are subject to uncertainties and consequently are often conservative.

Line 389               insert “beneficiation”: “2. Mineral beneficiation and processing,”

Line 395               “(29) The presence of NORM with elevated radionuclide concentrations could be an issue”

                                See our remarks under ambiguity.

Line 397-402       “(30) By-products and residues from a one industry involving NORM can be used as feedstock by other industry involving NORM and/or in common practices (e.g. building materials). In that sense, after being brought to surface (or else introduced into the industrial sector by another means), NORM enters a cycle, which is possibly endless (i.e. NORM can be moved and/or reprocessed from place to place), and enhanced exposures due to NORM may occur during all stages of the cycle.”

                                  Ambiguous use of the term NORM. As soon as some chemical processing occurs the naturally occurring radionuclides (NOR’s) will end up in another matrix (that due to the fact that the NOR’s move to this matrix is called NORM again. So here is also a mix up of the process stream NORM (may be ‘waste’ for industry 1) that is reused in another process in industry 2 thereby forming a new NORM process stream etc.

Line 434               “The process in which NORM in raw materials is concentrated, …”

                                  Actually the concentration of NOR’s becomes higher when these elements move  from the raw material into the reuse or waste stream. Here the term NORM clearly point to the radioactive elements themselves.

Line 539               “If an ongoing industrial process involving NORM, not previously identified …”

  See remarks under line 397-402. Again the naturally occurring radionuclides are meant, neither the NORM going into the process, nor the NORM produced by the process.

Line 543               “(48) For industries involving NORM in the national list, when a new process using NORM is to be implemented …”

                                  Again ambiguous (maybe even dubious) use of the term NORM. See remarks under line 397-402 and 539.

Line 548               “… a decision that the NORM process, as a whole, would need to be considered unjustified.”

                                  A better descriptive, less dubious term is needed taking into account the remarks under line 397-402 and 539.

Line 570               “…, NORM processes may pose environmental risks from other constituents, …”

                                  Apart from the term NORM processes (cf. remark line 548) it is not clear what is mentioned by this phrase (likely? ‘other environmentally hazardous constituents  can be released in the process than only naturally occurring radionuclides’).

Line 645               replace “…, the distribution of individual doses for both workers and members of the public may be very large.” by “…, the distribution of individual doses for both workers and members of the public may be very wide.”

Line 646               insert/replace “The protection efforts should focus individuals on the higher dose tail…” between/by “The protection efforts should focus on individuals in the higher dose tail…”

Line 769               replace “… the aim of identifying the distribution of NORM radionuclides and their activity concentrations throughout the industrial process, …” by “… the aim of recognising the identification and the distribution of naturally occurring radionuclides (NOR’s) and their activity concentrations throughout the industrial processing units, …”

Line 771               replace “… particulates, NORM distribution …” by “… particulates, naturally occurring radionuclide (NOR) distribution …”

                                  Clear example of ambiguity of the term NORM. Here you are actually like to refer to the radionuclides themselves, not to the material/matrix where these radionuclides are embedded.

Line 779               replace “… work with NORM.” by “… work with NORM.”

Line 833               replace “… as mineral processing plants can be very dusty, …” by “… as mineral processing plants may be very dusty, …”

Line 944               “… radionuclide mobility” add “… radionuclide mobility under ambient conditions”

                                mobility of elements [(radio)nuclides] may change upon bringing the nuclides into an oxidic environment (e.g. U not mobile under reducing conditions, but becomes mobile in aqueous after/by complex formation (UO₂)²⁺ uranyl-ions)

Line 979               replace “Depending on level of radioactivity …” by “Depending on the activity concentration …”

Paragraph 125   This paragraph makes no sense. Please rewrite.

Line 1083             replace “… disturb the NORM radionuclides equilibrium.” by “… disturb the secular equilibrium of ²³²Th and/or ²³⁸U decay series.”

Line 1095             replace “… on elevated NORM activity concentration in the …” by “… on elevated naturally occurring radionuclide (NOR) activity concentration in the …”

Line 1108             “(129) The EIA should consider the total impact of NORM activity, which for the specific purpose of protecting the environment from the harmful effects of radiation entails:

• Radiological characterisation of NORM discharge, including the data on background NORM levels;”

  Again the impact of the naturally occurring radionuclides (NOR’s) should be considered, where the chemistry of the matrix, in which these NOR’s are contained ultimately determines the NOR-mobility. Please adapt this paragraph, so that it clear what is actually mentioned.

Line 1121             “(130) For radiological characterisation of NORM released in the environment, it is necessary to perform the site-specific analysis of radionuclides with respect to their physical and chemical forms and activity concentrations in source, …”

  Guess one likes to identify the NORs present in the matrix released to the environment. Furthermore, it will be very hard for non-supported naturally occurring radionuclides (NOR’s) like ²²⁸Ra, ²²⁸Th (ingrowth, unsupported when no ²³²Th is present), ²²⁴Ra, ²²⁶Ra, ²¹⁰Po, as physical and chemical form analysis depends on standard analysis methods (e.g. XRD). For these type of analysis the NOR concentrations are below detection/identification limits.

Paragraph 133   This paragraph is a bit fuzzy. Please rewrite.

Line 1155             “(134) NORM in industrial processes may …”

                                  It is not the NORM calling for attention, the presence of naturally occurring radionuclides (NOR’s) in a certain matrix that calls for attention. The correlation between “industries involving NORM” is that they all exploit natural resources from the ‘soil’ or even (much) deeper geological layers. So, initially the matrix may be a gas (e.g. radon in natural gas), liquid (e.g. radium and/or lead [ions] in aqueous media) or solid (e.g. primordial ²³²Th and ²³⁸U generally in full secular equilibrium within their decay series).

The NVS observed the following typographical errors

Line 130               “Th-232” should be “²³²Th”

Line 375               Table 2.2 for the activity “Use of metal recycling slag for road construction” the “radionuclide with the highest activity concentration” is “²²³Ra”. This should be ²²⁶Ra instead of ²²³Ra.

Line 444               “The relevant dose criteria is the reference level, …” the sentence should be phrased either as singular or as plural, so “The relevant dose criterion is the reference level, …”or “The relevant dose criteria are the reference levels, …”

Line 447               “(ICRP, 20014a).” should be “(ICRP, 2014a).”

Line 701               “Radon” should be “radon”

Line 1133             delete “… are which present …” delete ‘are’ “… are which present …”