3.1. Paragraphs 3.1–3.4 of GSR Part 3 [2] specify the scope of application of the requirements for planned exposure situations. The scope is defined in terms of the practices involved and the exposures to sources within practices. With regard to exposure to radiation from natural sources, para. 3.4 of GSR Part 3 [2] states that such exposure is normally subject to the requirements for existing exposure situations (see Section 5). Only in certain cases do the requirements for planned exposure situations apply (see paras 3.159 and 3.161).
3.2. GSR Part 3 [2] requires any person or organization intending to carry out any activity within the scope of application of the requirements to submit a notification to the regulatory body of such an intention. Notification alone is sufficient provided that the exposures expected to be associated with the practice or action are unlikely to exceed a small fraction of the relevant limits, as specified by the regulatory body, and that the likelihood and magnitude of potential exposures and any other potential detrimental consequences are negligible.
3.3. Where notification alone is not sufficient, the person or organization concerned is required to apply to the regulatory body for authorization, which takes the form of registration or licensing. Typical practices that are amenable to registration are those for which: (i) safety can largely be ensured by the design of the facilities and equipment; (ii) the operating procedures are simple to follow;
(iii) the safety training requirements are minimal; and (iv) there is a history of few problems with safety in operations. Registration is best suited to those practices for which operations do not vary significantly.
3.4. One of the primary responsibilities of management with regard to occupational exposure is set out in Requirement 21 of GSR Part 3 [2]:
“Employers, registrants and licensees shall be responsible for the protection of workers against occupational exposure. Employers, registrants and licensees shall ensure that protection and safety is optimized and that the dose limits for occupational exposure are not exceeded.”
3.5. In terms of para. 3.78 of GSR Part 3 [2], where a worker’s exposure arises from sources that are not required by, or directly related to, the work, the management is required to provide that worker with the same level of protection against such exposure as members of the public.
3.6. In accordance with the graded approach to regulation (see paras 2.20–2.22), the government or the regulatory body is required to determine which practices or sources within practices are to be exempted from some or all of the requirements of GSR Part 3 [2], including the requirements for notification, registration or licensing (see para. 3.10 of GSR Part 3 [2]). Similarly, the regulatory body is required to approve which sources, including materials and objects, that are already within a notified practice or an authorized practice may be cleared from regulatory control (see para. 3.12 of GSR Part 3 [2]). Exemption or clearance is the appropriate regulatory option if the radiation risks are too low to warrant regulatory control or if the imposition (or retention) of regulatory control would yield no net benefit (see paras I.1–10 of GSR Part 3 [2]).
3.7. In terms of paras I.2 and I.11 of GSR Part 3 [2], the general criterion for exemption or clearance without further consideration is an effective dose of the order of 10 μSv or less in a year (or 1 mSv or less in a year in the case of low probability scenarios). However, for bulk material containing radionuclides of natural origin, the 10 μSv criterion is not appropriate, since it is one or two orders of magnitude below the normal variations in exposure to natural background
radiation. For such material, the criterion for exemption is an effective dose of the order of 1 mSv or less in a year (para. I.4 of GSR Part 3 [2]), while the criterion for clearance is an activity concentration of 1 Bq/g or less for each radionuclide in the 238U decay series and the 232Th decay series, and 10 Bq/g or less for 40K (or, for certain residues, an effective dose of 1 mSv or less in a year) (see para. I.12 of GSR Part 3 [2]).
OPTIMIZATION General
3.8. Paragraphs 3.76(b) and 3.77 of GSR Part 3 [2] state that:
“3.76. Employers, registrants and licensees shall ensure, for all workers engaged in activities in which they are or could be subject to occupational exposure, that:
…….
(b) Protection and safety is optimized in accordance with the requirements of these Standards;
…….
“3.77. Employers, registrants and licensees:
(a) Shall involve workers, through their representatives where appropriate, in optimization of protection and safety;
(b) Shall establish and use, as appropriate, constraints as part of optimization of protection and safety.”
3.9. For control of occupational exposure in planned exposure situations, guidance on meeting the relevant requirements of GSR Part 3 [2] for optimization of protection and safety is provided in paras 3.10–3.18. Further information of a more practical nature is provided in Ref. [17].
3.10. Optimization of protection and safety should be considered at all stages in the lifetime of equipment and installations, in relation to both exposures from normal operations and potential exposures. As a consequence, all situations — from design through operation to decommissioning and waste management — should be considered in the optimization procedure.
3.11. From a practical viewpoint, the requirements for optimization call for an approach that:
(a) Considers all possible actions involving the source(s) and the way workers operate with or near the source(s).
(b) Implies a ‘management by objective’ process with the following sequence:
planning, setting objectives, monitoring, measuring performance, evaluating and analysing performance to define corrective actions, and setting new objectives.
(c) Can be adapted to take into account any significant change in the state of techniques, the resources available for the purposes of protection or the prevailing societal context.
(d) Encourages accountability, such that all parties adopt a responsible attitude to the process of eliminating unnecessary exposures.
3.12. The quantity collective effective dose can be used as an instrument for optimization, for comparing available radiological technologies and for protection procedures. This quantity takes account of the exposure of all individuals in a group over a given time period or during a given operation executed by this group in designated radiation areas. The collective effective dose is calculated as the sum of all individual effective doses over the time period or during the operation being considered and is expressed in man-sieverts (man Sv).
3.13. The process of optimization should take account of:
(a) The resources available for protection and safety;
(b) The distributions of individual exposure and collective exposure in different groups of workers;
(c) The probability and magnitude of potential exposure;
(d) The potential impact of actions for the purposes of radiation protection on the level of other (non-radiological) risks to workers or to members of the public;
(e) Good practices in relevant sectors;
(f) Societal and economic aspects.
3.14. Some of the options considered in the optimization of protection and safety for workers may lead to increased exposure of other persons or, in the medical field, a reduction in the efficacy of the clinical procedure. Such impacts should be taken into account in the optimization process, especially when considering the establishment of administrative controls and the use of personal protective equipment. In particular, the arrangements for the protection of medical staff
should not lead to a reduction in the protection of the patient or a deterioration in the clinical outcome.
3.15. In general, incremental benefits to be obtained in terms of dose reduction decrease progressively as the associated expenditure increases. Even the cost of considering the ways in which doses may be reduced can become significant compared with the benefit to be achieved. At some stage, the effort might not be worthwhile for low doses. In this context, it is noted that para. 3.10 of GSR Part 3 [2] provides for the exemption of practices from regulatory control when an assessment shows that exemption is the optimum option for protection.
This provision is simply a recognition of the more general concept of diminishing returns.
3.16. The optimization of protection and safety should be considered at the design stage of equipment and installations, when some degree of flexibility is still available. The use of engineered controls should be examined carefully at this stage in defining the protection options. In image guided interventional procedures, for example, where there is a potential for workers to receive a significant dose to the lens of the eye, attention should be paid to the installation of fixed shielding and to the selection of equipment. Even if protection has been optimized at the design stage, however, the requirements for optimization in the operational phase still apply. At this stage, the content and the scale of the optimization process will depend on the situation. For example, when dealing with X ray machines, the optimization process can be quite straightforward, involving local rules and appropriate training of the operators. For nuclear facilities, situations are more complicated, and a structured approach should be followed as part of the radiation protection programme, including the use of decision aiding techniques (see paras 3.24–3.27), the establishment of dose constraints (see paras 3.28–3.33) and the establishment of investigation levels (see paras 3.122–3.128).
3.17. Optimization of protection and safety in operation is a process that begins at the planning stage and continues through the stages of scheduling, preparation, implementation and feedback. This process of optimization through work management is applied in order to keep exposure levels under review and to ensure that they are as low as reasonably achievable. The elaboration of a radiation protection programme, adapted to the specific situation, is an essential element of work management.
3.18. The management should record information on the way in which optimization of protection and safety is being applied and should disseminate the information, as appropriate. This information could cover the following:
(a) The rationale for proposed operating, maintenance and administrative procedures, together with other options that have been considered and the reasons for their rejection;
(b) Periodic review and trend analysis for doses due to occupational exposure of individuals in various work groups, and other performance indicators;
(c) Internal audits and peer reviews, and the resulting corrective actions;
(d) Incident reports and lessons to be learned.
Commitment to optimization of protection
3.19. The primary responsibility for optimization of protection and safety lies with the management. Commitment to an effective protection and safety policy is essential at all levels of the management, but in particular at the senior level.
The commitment of the management should be demonstrated by means of written policy statements that make radiation protection criteria an integral part of the decision process, and by provision of adequate resources and clear and demonstrable support for those persons with direct responsibility for radiation protection in the workplace.
3.20. The senior management should translate its commitment to optimization of protection and safety into effective action by incorporating optimization into an appropriate radiation protection programme, commensurate with the level and nature of the radiation risks presented by the practice. The scope of such a programme is set out in para. 3.60.
3.21. Workers should also have a commitment to protection and safety. The employer should ensure that mechanisms are in place by which workers can be involved, as much as possible, in the development of methods to keep doses as low as reasonably achievable, and have the opportunity to provide their views on the effectiveness of radiation protection measures.
3.22. Optimization of protection and safety is a regulatory requirement. The regulatory body should be committed to optimization of protection and safety, and should encourage its application. Where necessary, the regulatory body should undertake all relevant actions to enforce regulatory requirements on the management to apply this principle.
3.23. The management should ensure that training programmes, with content and duration commensurate with, and adapted to, the functions and responsibilities of the staff concerned, are provided for staff at all levels, including the senior management. The staff of regulatory bodies should have the training necessary to ensure that optimization of protection and safety is appropriately applied and enforced.
Use of decision aiding techniques
3.24. The process of optimization of protection and safety using decision aiding techniques can range from intuitive qualitative analyses to quantitative analyses, but should be sufficient to take all relevant factors into account in a coherent way, so as to contribute to achieving the following objectives:
(a) To determine optimized measures for protection and safety for the prevailing circumstances, with account taken of the available options for protection and safety as well as the nature, magnitude and likelihood of exposures;
(b) To establish criteria, on the basis of the results of the optimization process, for restriction of the magnitudes of exposures and of their probabilities by means of measures for preventing accidents and mitigating their consequences.
3.25. In most situations, a qualitative approach based on professional judgement will be sufficient for deciding upon the most favourable level of protection that can be achieved. In more complex situations, particularly those having significant implications for expenditure (e.g. at the design stage of installations), the use of a more structured approach may be appropriate. Some complex situations may be quantifiable using cost–benefit analysis or other quantitative techniques. In other cases, however, it may not be possible to quantify all of the factors involved, or to express them in commensurate units. It may also be difficult to make a balance between collective doses and individual doses, and between doses to workers and doses to the public, and to take account of broader societal factors.
For these situations, qualitative decision aiding techniques such as multicriteria analysis can be useful.
3.26. A structured approach to the selection of appropriate measures for protection and safety should include the following steps, with account taken of exposures from normal operations and of potential exposures:
(a) Identify all practicable protection options that might potentially reduce the occupational exposure;
(b) Identify all relevant economic, societal, radiological and, where appropriate, non-radiological factors for the particular situation under review that distinguish between the identified options (e.g. collective dose, distribution of individual dose, impact on public exposure, impact on future generations and investment costs);
(c) Quantify, where possible, the relevant factors for each protection option;
(d) Compare all options and select the optimum option(s);
(e) Where appropriate, perform a sensitivity analysis (i.e. evaluate the robustness of the solutions obtained by testing using different values for the key parameters for which recognized uncertainties exist).
3.27. Whatever the situation, decision makers should keep in mind that decision aiding techniques do not necessarily provide the definitive answer, nor do they provide the only possible solution. These techniques should be seen as tools to help structure problems in order to compare the relative effectiveness of various possible options for protection and safety, to facilitate the integration of all relevant factors and to assist in taking coherent decisions.
Dose constraints
3.28. Paragraph 1.22 of GSR Part 3 [2] states that:
“Dose constraints…are used for optimization of protection and safety, the intended outcome of which is that all exposures are controlled to levels that are as low as reasonably achievable, economic, societal and environmental factors being taken into account. Dose constraints are applied to occupational exposure and to public exposure in planned exposure situations.”
For occupational exposures, a dose constraint is a source related value of individual dose used to limit the range of options considered in the process of optimization, and it will always be a fraction of the dose limit. Paragraph 1.22 continues that:
“Dose constraints are set separately for each source under control and they serve as boundary conditions in defining the range of options for the purposes of optimization of protection and safety. Dose constraints are not dose limits: exceeding a dose constraint does not represent non-compliance with regulatory requirements, but it could result in follow-up actions.”
3.29. Paragraph 1.23 of GSR Part 3 [2] states that:
“While the objectives of the use of dose constraints for controlling occupational exposure and public exposure are similar, the dose constraints are applied in different ways. For occupational exposure, the dose constraint is a tool to be established and used in the optimization of protection and safety by the person or organization responsible for a facility or an activity.... After exposures have occurred, the dose constraint may be used as a benchmark for assessing the suitability of the optimized strategy for protection and safety...that has been implemented and for making adjustments as necessary. The setting of the dose constraint needs to be considered in conjunction with other health and safety provisions and the technology available.”
3.30. The objective of applying a dose constraint is to place a ceiling on values of individual dose — doses from a source, a set of sources in an installation, a practice, a task or a group of operations in a specific type of industry — that could be considered acceptable in the process of optimization of protection for those sources, practices or tasks. Depending on the situation, the dose constraint can be expressed as a single dose or as a dose over a given time period. The setting of any dose constraints should be such that dose limits for occupational exposure are complied with when workers incur exposures from multiple sources or tasks.
3.31. To apply the optimization principle, individual doses should be assessed at the design and planning stage, and it is these predicted individual doses for the various options that should be compared with the appropriate dose constraint.
Options predicted to give doses below the dose constraint should be considered further; those predicted to give doses above the dose constraint should normally be rejected. Dose constraints should not be used retrospectively to check compliance with the requirements for protection and safety.
3.32. Dose constraints should be used prospectively in optimizing radiation protection in various situations encountered in planning and executing tasks, and in designing facilities or equipment. They should, therefore, be set on a case by case basis in accordance with the specific characteristics of the exposure situation.
Since dose constraints are source related, the source to which they relate should be specified. Dose constraints should be set in consultation with those involved.
Regulatory bodies may use them in a generic way — for categories of similar sources, practices or tasks — or specifically, in authorizing individual sources, practices or tasks. The establishment of constraints may be the result of interaction
between the regulatory body, the affected operators and, where appropriate, workers’ representatives. As a general rule, it would be more appropriate for the regulatory body to encourage the development of constraints for occupational exposure within particular industries and organizational groupings, subject to regulatory oversight, than to stipulate specific values of constraints.
3.33. The process of deriving a dose constraint for any specific situation should include a review of operating experience and feedback from similar situations, if possible, and considerations of economic, societal and technical factors. For occupational exposure, experience with well managed operations is of particular importance and should be considered in setting constraints. National surveys or international databases that capture a large amount of experience with exposures relating to specific operations can be useful for such purposes.
DOSE LIMITATION
3.34. Paragraph 3.76(a) of GSR Part 3 [2] states that:
“Employers, registrants and licensees shall ensure, for all workers engaged in activities in which they are or could be subject to occupational exposure, that:
(a) Occupational exposure is controlled so that the relevant dose limits for occupational exposure specified in Schedule III are not exceeded”.
3.35. In accordance with para. III.1 of GSR Part 3 [2]:
“For occupational exposure of workers over the age of 18 years, the dose limits are:
(a) An effective dose of 20 mSv per year averaged over five consecutive
(a) An effective dose of 20 mSv per year averaged over five consecutive