|These comments are made jointly by a group of professional staff members of the Division of Radiation, Transport and Waste Safety (NSRW), IAEA, to whom the topic of scope of radiation protection measures is of particular interest and relevance for the development of international standards.
The draft document on “The Scope of Radiological Protection Regulations” is welcomed as an important step forward in clarifying a number of issues that, until now, have not been properly resolved or have been the subject of differing interpretations and confusion. Such clarification and, importantly, the supporting discussion, will be of great significance and value in the ongoing development and review of the Standards. The document represents a positive step forward in improving understanding (including clarity on the meaning of specific terms) and practicability (e.g. flexibility where it is needed).
The group welcomes in particular the following aspects of the draft document:
• The greater clarification now provided in terms of the use of the concepts of exclusion and exemption for practices, which will in turn lead to a greater consistency of understanding around the world;
• The flexibility provided through the option of using the term ‘generic exemption’ as an alternative to exclusion, thus retaining a common conceptual approach, i.e. defining what can (or cannot) reasonably be controlled, while allowing for differences in national legal practice as to the exact mechanism involved;
• The greater attention now given, in a general sense, to situations involving exposure to radionuclides of natural origin, an aspect that was not sufficiently clear in the past;
• The reduced emphasis on the specific issue of controlling cosmic ray exposure in aircraft;
• The recognition of the fact that the dose criterion for exemption has lost its intended flexibility through having become entrenched at 10 ìSv/a, and the recommendation that this value should be seen more as the bottom end of a range extending up to about 1 mSv/a.
However, the group has identified a few aspects of the document that could lead to unnecessary complications or difficulties in achieving universal acceptance of the recommendations contained therein, and in translating these into standards that are practicable to implement. These aspects, particularly the main concerns outlined in points 1–5 below, would need to be addressed before the group could lend its full support to the publication of the document.
1. The title of the document refers to radiation protection regulations. This could lead to a perception that the Commission is getting too involved in legislative and regulatory matters. Furthermore, the title is not consistent with the fact that the document goes beyond giving recommendations that are applied only through regulation — there are other means of controlling exposures, for instance when dealing with radon exposure in dwellings. The term “regulation” is usually associated only with the control of a practice.
It is suggested that the word “Regulations” in the title (and in the relevant text throughout the body of the document) could be replaced by a more appropriate, broader term such as “Controls” or “Measures”.
2. A related point is the use of the term “exemption”. Up to now, this term has largely been associated with the regulatory decision-making process, in the sense that it implies a decision not to apply regulatory controls because they are not warranted, and is thus a term associated largely with practices. The extension of the use of this term to all types of intervention situations could cause confusion, and seems to be unnecessary. In terms of current ICRP recommendations, and as incorporated into the Standards, intervention situations are handled through the use of action levels that define the threshold below which intervention action is deemed to be unwarranted. The document does not explain why, below the action level, there is a need for a separate exemption level (and, indeed, an exclusion level as well!), and it is suggested that these additional levels serve no useful practical purpose. Furthermore, they clearly add to the level of complexity of the system of radiological protection — the opposite of what was intended. The extension of the concept of exemption in this way would certainly cause problems for adoption into the Standards.
It is suggested, therefore, that the action level (or the lowest value of the action level if a range is specified) should continue to be used as the sole means of defining what should not be considered for intervention — in other words, maintain the status quo.
3. A more specific concern related to that outlined in (2) above is the introduction of an exclusion level of 40 Bq/m3 for exposure to radon. This level corresponds to the arithmetic mean for indoor radon. There is no explanation given as to why such a value is chosen. It would appear to have no sensible foundation, because it would imply that a substantial portion of homes worldwide with ‘normal’ radon levels would become, almost arbitrarily, included within the scope of control for no useful purpose. Even if there were to be merit in setting an exclusion level, it would be logical to set it at the upper end of the range of normal radon concentrations in homes, which would imply a value of at least 100 Bq/m3.
4. There is no clear indication as to the derivation of the proposed exclusion levels of 1 Bq/kg (alpha emitters) and 10 Bq/kg (beta and gamma emitters) and, in particular, the way in which they are supposed to represent the levels at which such radionuclides become ‘amenable to control’. Just because they are “minute and difficult to monitor” (para. (123)) is not a good reason for adopting them as exclusion levels. Furthermore, it should be clarified in para. (123) that they do not apply to radionuclides of natural origin. There does not seem to be any real need for setting exclusion levels corresponding to these values — they are so low that they will be of no practical use, and the specification of such values will be of no obvious benefit to the Standards.
It is suggested that reference to these proposed exclusion levels be removed.
5. There is not enough discussion of the use of collective dose. It is important for comparing practices or remediation actions, but there seems to be no clear value in using it as a criterion for exemption. Indeed, it causes confusion and problems when attempts are made to apply it in this manner to practices involving NORM, for instance in the use of phosphate fertilizer (collective dose 10 000 man•Sv in a year) or the use of phosphogypsum as a soil conditioner. It is stated in para. (50) that the individual dose is always the limiting criterion. This implies that the use of collective dose for exemption purposes should be discontinued, and a statement to this effect would be useful.
The group has also identified some other, more specific points that may warrant attention, as follows:
• The discussion relating to a value of 1 mSv/a as representing a possible criterion for case by case exemption of practices involving NORM could be better stated. More emphasis should be given to exemption being an outcome of controllability considerations and the optimization of protection (i.e. regulation should produce a positive net benefit), and to the value of 1 mSv/a being merely an indication of the upper end of the range of doses likely to be received from exempt practices involving NORM.
• It could be argued that too much emphasis is placed on the use of international agreements as the basis for various recommendations, especially in cases where no independent review by the Commission has been carried out. References to such international agreements should perhaps take the form of examples only.
• The statement that the international agreements reached on radiological criteria for foodstuffs could provide the basis for exemption could lead to confusion because these criteria were determined for use during the aftermath of an emergency. A more thorough explanation is needed. Moreover, it is questionable whether the use of the exemption concept is even appropriate for foodstuffs, or for drinking water, if exemption is deemed to apply only to practices. Perhaps an action level approach would be better.
• Figure 2 is very useful in helping to illustrate the system of exemption and clearance. Would it be possible to extend this is some way to illustrate how waste disposal and authorized discharges fit into the picture?
• In para. (i) of the Executive Summary, it is incorrect to refer to the “sum of the activity concentrations”. The formula to which this refers (given in para. (101)) is a sum of quotients, not a sum of activities.
• In para. (l) of the Executive Summary, the items mentioned in (ii) are candidates for conditional exemption, and are thus not strictly in the same category as those in (i). In general, para. (l) is important and maybe not sufficiently emphasized. However, the levels given could arguably be adopted as exclusion levels rather than exemption levels. This needs further consideration.
• In para. (o) of the Executive Summary, it does not make sense to say that certain sources complying with exemption criteria might still need notification or registration. This is a contradiction in terms.
• Para. (p) of the Executive Summary is of fundamental importance, and should be stated much earlier rather than at the end of the summary. Unfortunately, the position adopted in this statement is not maintained consistently throughout the body of the document — for instance, contrary to what is stated in para. (p), the Commission is quite categorical about the use of exclusion and exemption in its discussion on radon. This needs to be addressed to avoid inconsistencies and contradiction.
• In para. (33), it is stated that judgement on the part of the legislator on what is unamenable to control, and thus excluded, may be influenced by cultural expectations and can therefore differ substantially around the world. This is true, but perhaps not enough emphasis is given in the document to the importance of overcoming or avoiding these differences in the interests of harmonization. It should be clarified that differences in public acceptance can be accommodated in dealing with the justification of practices and the setting of intervention levels, but this does not mean that the same reasoning can apply to exclusion.
• In para. (69):
(i) The references to “IAEA 1999” should be to “IAEA 1996”.
(ii) In the seventh line, immediately before the sentence beginning with “The requirements...”, it is suggested that the following new sentences be added: “However, the intervention levels in the BSS [IAEA 1996] do not address all protective actions (e.g. individual decontamination). Moreover, the guidance in Schedule IV, which relates to the occurrence of deterministic health effects, does not address all important organs or exposure pathways (e.g. it does not address inhalation of radionuclides emitting particles with high LET).”
(iii) In line with the general concern mentioned in (2) above, the suggestion in this paragraph that the concepts of intervention and action levels could be considered as de facto exemption levels is likely to lead to confusion — it is again stressed that the application of the concept of exemption should not be extended to cover intervention situations.
(iv) It is suggested that the following sentences be added at the end of the paragraph: “The issue of an extended framework for intervention levels in an emergency exposure situation has recently been addressed in IAEA TECDOC 1432 Development of an extended framework for emergency response criteria [IAEA 2005], which forms the basis for an IAEA Safety Guide currently in preparation, on criteria for use in planning response to nuclear and radiological emergencies.”
• In the penultimate line of para. (76), “generic intervention level” should presumably be “generic exemption level”;
• The wording of para. (107) needs further refinement. While abnormally high levels in homes are reasonably controllable, normal ambient levels are not. Furthermore, while the incorporation of radon control requirements into national building codes is certainly happening in some countries, it is questionable whether this has yet reached the level of “common practice” on a worldwide basis;
• In para. (114), more emphasis should be given to restating the existing recommendation that the radon action level for remedial action in workplaces should also become the level at which the exposure to radon starts to become treated as a practice if reasonable remediation efforts are unsuccessful in achieving the necessary reductions in radon concentration.