Preface, Glossary, Executive Summary

At its meeting in Paris, France, in March 2005, the International Commission on Radiological Protection (ICRP), hereinafter referred to as ‘the Commission’, established a Task Group charged to develop recommendations for assisting regulatory authorities to define the scope of radiological protection regulations, by exploring, in particular, the concepts of exclusion and exemption that are already established in international standards.

The final membership of the Task Group was as follows:

The membership of the Main Commission during the preparation of this report was:

For the preparation of the first draft of the report, the Task Group met at the Laboratories of the UK Health Protection Agency (HPA) in Chilton, UK. The Commission wishes to express its appreciation for the support received by the Task Group from the HPA.

The Task Group benefited from further discussions with consultants convened by the International Atomic Energy Agency (IAEA) to develop working material on scope within the framework of the process being undertaken by international intergovernmental organisations for reviewing the International Basic Safety Standards for the Protection against Ionizing Radiation and the Safety of Radiation Sources. The consultancy meeting took place at the IAEA headquarters in Vienna on 30 January–2 February 2006, and included the participation of Georges H. Coppée, representing the International Labour Organization, John R. Cook (transport aspects), Alan Melbourne, Denis Wymer, and Trevor Boal, as well as Anthony Wrixon. The Commission wishes to express its appreciation to the consultants and the IAEA for their contribution to the Task Group’s work. The Commission is also very grateful for the extensive contributions made to the report by the Nuclear Energy Agency’s Expert Group on the Implications of ICRP Recommendations and the European Commission.

The draft report was reviewed by the Commission at its meeting in Bern, Switzerland, in September 2005 and displayed on the ICRP website for comments in March 2006. Several useful suggestions were received during the web consultation. The subject matter of the present report is such that in a number of respects, several alternative positions could have been defensible; therefore, the report is quite discursive, and many of the comments received were reasoned rather than persuasive. Due to the nature of this report, the web comments have not just been taken into account, but many have, exceptionally, been cited and referenced in the report.

Following revision by an ad-hoc group of the former and current Chairmen of the Commission, Roger Clarke and Lars-Erik Holm, and the Task Group Chairman, the report was approved by the Task Group by postal ballot and reviewed by the Commission at its meeting in Rabat, Morocco, in October 2006. Following the approval by the Commission of its new Recommendations at the meeting in Essen in March 2007, the report was updated and approved by postal ballot by the Commission.

(a) This report offers advice to competent national authorities and relevant intergovernmental organisations for facilitating their definition of the scope of control measures for purposes of protecting people against possible adverse consequences of radiation exposure. As control measures are usually implemented through regulations, the report indirectly provides advice on the scope of radiological protection regulations. While the Commission’s recommendations for radiological protection are not limited in extent, regulations need to be limited in their reach for legal and practical reasons. Since the recommendations are widely used in the formulation of regulations, they influence the definition of the regulatory scope. The relevant basic principles of the recommendations are the justification and optimisation of control measures, within constrained individual doses, and they provide the basis for the advice offered in the report. Such advice should not be construed as interfering with the sovereignty of national legislation and the indispensable rights of the national regulators for establishing the scope of radiological protection control measures.

(b) The main concepts associated with the scope of radiological protection regulations are termed ‘exclusion’ and ‘exemption’. Exclusion refers to the deliberate omission of exposure situations from the scope of regulatory requirements, and exemption refers to waiving regulatory requirements if their application is not warranted. A special case of exemption, termed ‘clearance’, refers to the relinquishing of regulatory control if such control becomes unwarranted.

(c) The definition of scope can differ according to the various types of radiation exposure situation. The relevant situations to consider are: ‘planned exposure situations’, which are situations involving the deliberate introduction and operation of radiation sources; ‘emergency exposure situations’, which are situations that may occur during the operation of a planned situation, or from a malicious act, or from any other unexpected situation, and which require urgent action in order to avoid or reduce undesirable consequences; and ‘existing exposure situations’, which are exposure situations that already exist when a decision on control has to be taken, including prolonged exposure situations that result from radioactive residues that may remain in the long term after emergencies. Planned exposure situations are normally within the scope of regulatory requirements for radiological protection and, therefore, the concepts of exclusion, exemption, and clearance may be used to justify and optimise regulatory control by avoiding the application of unamenable or unwarranted control measures. Conversely, in emergency exposure situations the concepts of exclusion, exemption, and clearance do not play a meaningful role; however, prolonged exposure situations remaining in the long term after math of an emergency exposure situation may be treated as a de-facto existing exposure situation. Many existing exposure situations fall outside the scope of regulatory requirements because the criteria for exclusion are met; however, regulatory controls may be required when it is considered that they are justified and warranted.

(d) Societal attitudes to the control of exposure situations may vary and be dichotomous. Usually, people have higher demands for controlling ‘artificial’ exposure situations than for dealing with ‘natural’ exposure situations. When dealing with natural radioactivity, determining whether or not a given situation should be subjected to radiation protection requirements is particularly complex. However, natural sources of exposure should, in principle, be controlled coherently and consistently with other sources regardless of their origin or magnitude. Nevertheless, account should be taken not only of the justification and optimisation of controlling measures, but also of the different expectations of those affected by the exposure situations.

(e) Depending on the relevant national regulatory systems, legislators or regulators should consider application of the concept of ‘exclusion’ to any exposure situation that is considered to be either uncontrollable or unamenable to control through regulation. These comprise many exposures arising from the natural environment, including exposures from cosmic radiation at ground level and from natural radioactive constituents of the human body. They may also include radioactive residues from past activities and events, and radioactive releases that were lawfully discharged to the environment from regulated human activity, but which may have become unamenable to further control. The concept of exclusion may also be considered for application to raw material extracted from the ground that contains radionuclides of natural origin in concentrations below a specified value.

(f) For planned exposure situations, radiological protection regulations should provide for the application of the concept of ‘exemption’ from specified regulatory requirements. Exemption allows regulators to release legal persons (which include natural persons with legal capacity) from compliance with specified requirements if they judge that the application of such requirements is unwarranted. The Commission recommends that exemption may be granted only if the following conditions are met: individual radiation risks to be incurred by those exposed must be acceptably small; protection must be considered to be optimised; there must not be appreciable likelihood of unintended scenarios that could lead to a failure to meet the previous conditions; and the legal persons to be exempted must be conducting activities that are considered to be justified. Materials or sites subject to regulatory requirements, but for which regulatory requirements have become unwarranted, can be exempted through the application of the concept of ‘clearance’. Regulatory control is relinquished upon clearance. The criteria for clearance should ensure that relinquishing control must, at least, not lead to an exposure situation that would fail to meet any of the conditions for exemption.

(g) For situations involving artificial sources of radiation, an individual dose criterion of approximately 10 μSv/year has been widely used for the purposes of exemption without further consideration. However, this should not be taken to be the sole criterion for granting exemption. It is the principle of optimisation rather than just the triviality of individual doses that should be considered as the basis for exemption. For situations involving radionuclides of natural origin, the national authority may establish levels for the purposes of exemption that are consistent with exemption being the optimum regulatory option.

(h) Agreements on generically derived exemption and clearance levels are being reached under the aegis of international intergovernmental organisations. They are expressed in terms of the following quantities: activity of a source at any one time; activity concentration in low amounts of material; activity concentration, irrespective of the amount of material, in a given situation or for unrestricted release; and activity or activity concentration of transported materials, irrespective of the amount, while the material is in transport. The Commission neither specifically endorses nor disapproves the use of these levels, but considers that this type of consensual intergovernmental generic guidance is very useful for purposes of international standardisation. While exemption levels are basically to be decided by national regulators, the use of those levels being developed under the aegis of competent international intergovernmental organisations should be encouraged. These generic levels, which seem to be widely accepted, should promote international coherence and consistency in matters of regulatory scope.

(i) For emergency exposure situations, the concepts of exclusion and exemption do not have a meaningful role. However, authorities responsible for emergency management may specify circumstances under which no emergency protective actions would be justified and warranted; but this would depend on optimisation of the protective strategy according to the specific situation. Prolonged exposure situations caused by radioactive residues remaining in the long-term aftermath of an emergency may be treated as a special case of an existing exposure situation.

(j) For existing exposure situations, the definition of scope should address whether or not the extant exposure is high enough for regulatory intervention to be justified, and whether the justified control measures are warranted or the protection is already optimised. The issue therefore is not whether or not regulations are justified or the expected increase in exposure is large enough to warrant the application of regulatory requirements (as in the case of planned exposure situations). Many existing exposure situations involving natural radiation and radioactive materials may be either excluded from the regulatory scope on the basis that regulation is not justified, or exempted from the application of regulatory requirements that are not deemed to be warranted. In these situations, regulations or their application would not be expected to lead to an improvement in protection sufficient to offset the societal efforts and possible detriment arising from regulatory enforcement and implementation. However, in some situations, regulations may specify levels defining a type of non-action ceiling above which some regulatory requirements would apply. For the existing exposure situations that may remain in the long-term aftermath following an emergency, consideration should be given to specifying optimum levels of activity of residual radioactive material above which regulatory requirements would apply to the legal person responsible for remediation. For levels corresponding to a residual annual dose of the order of 1 mSv and higher, control measures are likely to be justified, but higher or lower values may be appropriate in particular circumstances.

(k) For adventitious exposure to low-energy or low-intensity external exposure, some sources may be considered as candidates for exemption without further consideration. Apparatus and devices emitting radiation that are of a type approved by the regulator may be exempted if they meet the following criteria: (i) in normal operating conditions, they do not exceed an effective dose criterion that corresponds to an ambient dose equivalent rate or a directional dose equivalent rate, as appropriate, exceeding approximately 1 μSv/h at a distance of 0.1 m from any accessible surface of the apparatus or device; or (ii) the maximum energy of the emitted radiation is no greater than approximately 5 keV. Similarly, apparatus and devices containing radioactive material that are of a type approved by the national authority, and are not otherwise exempted, may be exempted provided that: (i) the radioactive material is in the form of a sealed source that effectively prevents leakage and direct contact with the material, and, (ii) in normal operating conditions, does not exceed an effective dose criterion that corresponds to an ambient dose equivalent rate or a directional dose equivalent rate, as appropriate, exceeding approximately 1 μSv/h at a distance of 0.1 m from any accessible surface of the apparatus or device.

(l) For regular exposure situations to cosmic radiation above the earth’s surface, such as in air travel, there seems to be no obvious reason to recommend additional regulatory controls to those already in place. National authorities may wish to monitor these situations until more information becomes available. Exceptional cases of cosmic radiation exposure, such as exposure in space travel, where doses may be significant and some type of control warranted, should be dealt with separately, taking into account the special type of situations that can give rise to this type of exposure.

(m) For exposure situations involving specified processed materials and by-products containing radionuclides of natural origin, consideration may be given to extending the use of exclusion beyond the case of raw materials, whenever their regulation is unjustified and should the legal national conditions permit. In jurisdictions where the mechanism of exclusion may not be appropriate, the concept of exemption may be applied to these products in order to achieve an equivalent objective. International intergovernmental organisations have developed guidance on criteria for exclusion and exemption in such exposure situations.

(n) For exposure situations to radon in buildings and workplaces, levels of activity concentration should be specified for which protection is considered to be optimised. Above these levels, controlling measures should be applied. (Such levels would therefore serve a different purpose from the reference levels recommended by the Commission, which delineate a dose level above which it is judged to be inappropriate to plan to allow exposures to occur, and below which optimisation of protection should be implemented.) In the case of workplaces, a single concentration value may continue to be used; this has been established through intergovernmental harmonisation for triggering the application of monitoring requirements for occupational radiological protection.

(o) For commodities containing small amounts of radionuclides, international intergovernmental organisations have developed radiological criteria applicable to international trade. These criteria cover non-edible commodities, foodstuffs, and drinking water. Again, these generic levels seem to be widely accepted, and should promote global coherence and consistency, and facilitate international trade.

(p) Whatever regulatory mechanisms are employed to address the different types of exposure situation, the recommendations in this report are intended to assist in defining what can be or needs to be the subject of regulatory requirements for radiological protection and, conversely, what does not. The application of regulatory control should achieve a net benefit in protection; otherwise, regulatory control is not justified. Similarly, regulatory requirements should be applied in a manner that optimises protection; otherwise, the application of regulatory requirements would not be warranted. Application of the concepts of exclusion and exemption, including clearance, can lead to regulatory systems that are justified and optimised for each exposure situation.

(i) The terminology used in this report is generally coherent and consistent with the glossary included in the Commission’s 2007 Recommendations (ICRP, 2007). The specific meaning given in the report to a number of terms and concepts is described hereinafter roughly alphabetically.

(ii) The adjective ‘adventitious’ is used to describe radiation exposure that is incidental to the use of apparatus and devices emitting ionising radiation.

(iii) The term ‘control’ is specifically used to mean restrictions imposed by regulatory authorities in order to manage radiation exposure situations. In languages other than English, the term is sometimes used to mean a different concept, such as verifying, authenticating, substantiating, corroborating, and confirming, but these are not the meanings intended in this report. Thus ‘control measures’ is used to denote the means for achieving the purpose of imposing regulatory restrictions on specific radiation exposure situations.

(iv) The adjective ‘dichotomous’ is firstly used to express the different and contrasting social perceptions of different exposure situations and their subsequent, consequent controls. This is particularly evident in the case of control of natural versus artificial exposure situations. ‘Dichotomous’ may imply a negative interpretation of the rationale behind differences; therefore, the term ‘non-uniform’ is used when referring to decision-making approaches to dichotomous situations (This term is more neutral, and reflects more accurately the fact that the bases for decisions may well be different in different cases.)

(v) The glossary in the Commission’s Recommendations (ICRP, 2007) includes the formal definitions of dosimetric quantities. In this report, ‘effective dose’ is used as the relevant quantity. The effective dose is taken to mean the sum of the time integral, over a period of time, of the effective dose rate due to external irradiation and the committed effective dose due to internal contamination caused by all intakes of radionuclides during that time. Normally, the effective dose will simply be termed ‘dose’ in the report, and generally used as an annual dose. While the unit of dose is the sievert (Sv), the unit used for this quantity in the report will be the millisievert (mSv), namely a thousandth of an Sv, and the microsievert (μSv), namely a millionth of an Sv. The report also uses a number of relevant dose-related terms, which are useful for the different exposure situations covered in the report, as follows.

• For planned exposure situations, the ‘additional dose’, which is a relevant concept in the context of exemption from regulatory control, is the dose that would arise should the situation be introduced. The additional dose would be added to the existing dose, which can be expected to increase marginally as a result of the introduction of a planned exposure situation.

• For emergency exposure situations, the ‘projected dose’, the ‘averted dose’, and the ‘residual dose’ are used. Projected doses are those that would be expected to be incurred due to an emergency, either if a specified countermeasure (i.e., a protective action, such as sheltering or evacuation), a set of countermeasures, or, in particular, no countermeasures were to be taken or not. Averted doses are those prevented or avoided by the application of countermeasures. Residual doses are those remaining after all protective actions have been undertaken.

• For existing exposure situations, the ‘existing or extant dose’, namely the dose in existence or being incurred, is used and usually expressed as an annual dose.

• The operational quantity ‘ambient dose equivalent’ is also used for defining exemption for specific apparatus and devices.

(vi) The term ‘naturally occurring radioactive material’ means radioactive material containing only radionuclides of natural origin. The term ‘radionuclides of natural origin’ is used restrictively just to mean ⁴⁰K and radionuclides in the decay chains of the primordial radionuclides. ⁴⁰K is a generalised contributor to exposure by virtue of its widespread distribution in nature, and because it is an important constituent of the human body. The primordial radionuclide decay chains are: the thorium series, headed by ²³²Th, the most abundant of all naturally occurring radionuclides and constituted mainly by ²²⁸Ra, ²²⁸Ac, ²²⁸Th, ²²⁴Ra, ²²⁰Rn, ²¹⁶Po, ²¹²Pb, ²¹²Bi, ²¹²Po, ²⁰⁸Tl, and ²⁰⁸Pb (stable); the uranium series, headed by ²³⁸U and constituted mainly by ²³⁴Th, ^234mPa, ²³⁴U, ²³⁰Th, ²²⁶Ra, ²²²Rn, ²¹⁸Po, ²¹⁴Pb, ²¹⁴Bi, ²¹⁴Po, ²¹⁰Pb, ²¹⁰Bi, ²¹⁰Po, and ²⁰⁶Pb (stable); and, less important for the purpose of this report, the actinium series, headed by ²³⁵U and constituted mainly by ²³¹Th, ²³¹Pa, ²²⁷Ac, ²²⁷Th, ²²³Fr, ²²³Ra, ²¹⁹Rn, ²¹⁵Po, ²¹¹Pb, ²¹¹Bi, ²⁰⁷Tl, and ²⁰⁷Pb (stable). Radionuclides produced by the action of cosmic rays such as ³H (tritium), ¹⁴C, and ²²Na, which are isotopes of elements with metabolic roles in the human body, and several other natural radionuclides, such as ⁸⁷Rb, ¹³⁸La, ¹⁴⁷Sm, and ¹⁷⁶Lu, are widespread in nature but at such low levels that their contribution to human exposure is negligible. Therefore, they have been excluded from consideration in the definition of ‘radionuclides of natural origin’ used in this report, simply because they are of trivial importance for the purpose of the report.

(vii) The concepts of ‘practices’ and ‘intervention’ were introduced by the Commission in Publication 60 (ICRP, 1991a, Para. 106), and defined as human activities that increase the overall exposure to radiation and that can decrease the overall exposure, respectively. The Commission now uses a situation-based approach to characterise the possible situations where radiation exposure may occur, and considers that the term ‘planned exposure situations’ better characterises its intentions for practices and ‘emergency exposure situations’ and ‘existing exposure situations’ for interventions. The term ‘practice’ has, however, become widely used in radiological protection for referring to human endeavours and activities whose introduction could lead to a planned exposure situation and may cause an increase in exposure to radiation or in the risk of exposure to radiation, as appropriate; therefore, the term ‘practice’ will be used in the report. The generic word ‘intervention’, and its derivatives, implying the concept of action or process taken to protect, will be used in the report but this should not be confused with the previous formal definition of intervention.

(viii) The term ‘[radiological protection] regulation’ (and its derived qualifier, ‘regulatory’) is used to mean the prescribed rules and authoritative directions in matters of radiological protection. These usually encompass not only the relevant legislation, or assembly of laws providing the legal basis for the radiological protection, but also the regulation proper that derives from the legislation. The latter includes the byelaws, governing principles, procedures and code of practice, standards and norms, directives (or authoritative instructions, directions, or order), and any other authoritative decision or pronouncement by a competent national authority. (Guidelines or general pieces of advice are sometimes considered de-facto regulations.) Thus, the term is normally used with the connotation of the system of rules and authoritative directions recognised by a country or community for regulating the protection against exposure to ionising radiation. It should be noted, however, that the use of regulatory terminology in the report should not lead to a perception that the Commission is getting involved in legislative and regulatory matters. The terms should be understood in the broader context of measures, control, or control measures (see below). The terms are used throughout the report and may sometimes be interpreted as referring to what is ‘in’ and what is ‘out’ of regulation. The recommendations for radiological protection are not limited in extent, but regulations need to be limited in their reach for legal and practical reasons. Therefore, the issue is not what is ‘in’ or ‘out’ of regulations, but rather what is or is not controlled. Legislation and regulation are necessary to define what is ‘controlled’ and what is not. To implement this concept, the word ‘control’, as in ‘radiological protection control regulation’, has been added in various points in the text to clearly emphasise this point.

(ix) Consequently, the term ‘regulator’ is used to mean those entrusted by the legislation to control or supervise radiation exposure situations by means of the radiological protection regulations. In legal systems derived from Roman civil law, it is used as a synonym of the term ‘procurator’ in the sense that it is a governmental agent representing the interests of those exposed to radiation. ‘Legislators’, on the other hand, are members of legislative bodies who make laws and establish legislation, including legislation entrusting regulators.

(x) The Commission uses the term ‘source’ to indicate any physical entity or procedure that results in a potentially quantifiable radiation dose to a person or group of persons. It can be a physical source (e.g. radioactive material or an x-ray machine), an installation (e.g. a hospital or a nuclear power plant), or procedures of groups of physical sources having similar characteristics (e.g. nuclear medicine procedures, or background or environmental radiation). If radioactive substances are released from an installation to the environment, the installation as a whole may be regarded as a source; if they are already dispersed in the environment, the portion of them to which people are exposed may be considered a source. Most situations will give rise to a predominant source of exposure for any single individual, making it possible to treat sources singly when considering protective actions. In general, the definition of a source will be linked to the selection of the relevant protection strategy, as appropriate, for the optimisation of protection. Difficulties will arise if the policy is distorted, e.g. by artificially subdividing a source in order to avoid the need for protective action, or by excessively aggregating sources to exaggerate the need for action. Provided that the national authority and the user (where one can be defined) both apply the spirit of the Commission’s broad policies, practical agreements can be made on the definition of a source (ICRP, 2007, Paras 174 and 175).

(xi) The adjective ‘unamenable’, i.e. not amenable (and its derivatives unamenability, etc.), is used throughout the report to mean incapable of being acted upon. Thus, a radiation exposure situation is said to be unamenable to control if it is reasonably unfeasible for the regulator to impose radiation protection restrictions on the situation. It is noted that in formal English, the term ‘unamenable’ is also used relating to persons with an implication of influencing their reasoning or willingness, or relating to their legal status or responsibility (Brunner, 2006), but these are not the meanings intended in this report.

(xii) The adjective ‘unwarranted’ is used to indicate that the application of regulatory requirements for radiological protection purposes may be considered unnecessary.

(xiii) The term ‘(radioactive) waste’ is used to mean radioactive material in gaseous, liquid, or solid form for which no further use is foreseen. ‘Waste disposal’ is the term used to describe the discarding of waste with no intention of retrieval, which usually covers the discharge of effluents and the disposal of solid waste. The whole sequence of operations starting with the generation of waste and ending with disposal is usually termed ‘waste management’. The report refers to the use of the term ‘clearance’ in some legal texts as equivalent to a lower boundary for the definition of radioactive waste. Radioactive materials for which no future use is foreseen, with activity levels above clearance levels, would be regarded as radioactive waste, whereas if their activity levels are at or below clearance levels, they would not be regarded as being radioactive for regulatory purposes.