Australian comments on the Draft ICRP Recommendations – Part 2 of 2 1. Controllable source ICRP proposal This is a key concept. Practice(s) retained but the distinction between these and interventions is no longer clear. Comments Further clarification on what constitutes a controllable source would be useful. There appears to be a lack of distinction between planned actions and responses to existing situations. More guidance is required. P8 – the term “single sources” could be defined for clarity. 2. Dose constraint ICRP proposal Constraints are quantified for all controllable sources in all situations. Another key concept with broad significance, including retrospective and regulatory use. Comments The broadening of the concept of the dose constraint is a significant change in the ICRP approach to radiation protection. The proposal that regulators should set their own dose constraints would require a considerable effort. P133 explains the purpose of dose constraints but does not state that they are mandatory, while P137 discusses a “mandatory constraint”. The two wordings could be usefully clarified: a mandatory constraint is not felt desirable. The justification for the figures in Tables S1 and 7 on the basis of background levels suggests replacement of the well-developed and defensible risk evaluation approach and would benefit from further explanation. There now seem to be three types of individual and three types of situation: this appears to make matters more complex and may cause confusion. ICRP proposal Figure 2 contains some confusing pictures. Medical exposures are excluded but both the public and worker parts of the diagram contain images that imply “medical”. Comments The confusing images should be removed. S6 – is there any difference in meaning between “responsible national authorities” and “regulators” (used in S3)? If so, their meanings should be clarified; if not, then the wording should be made consistent. ICRP proposal A proposed minimum dose constraint of 0.01 mSv in a year. Possible optimization below this level? Comments The use of the value of 0.01 mSv in a year as a dose constraint would benefit from a clear supporting case. 0.01 mSv in a year has gained some acceptance as being a ‘trivial’ level of dose and has been used as a basis for the exemption of various practices. If intended, the proposal that optimization is carried out at lower dose levels needs explanation. The maximum constraint of 100 mSv in a year applies to high levels of controllable existing exposures. Examples of these would be useful as, in theory, there should be no controllable doses in excess of 20mSv per annum or 50mSv for any one year in five? ICRP proposal P159 states that “The need for action is likely to be high if an effective dose from a single source is more than about a hundred times the global average background dose.” Comments Does this mean there is a need for action if it is possible for a person to receive a dose from a single source that is more than one hundred times the global average background dose or does it mean there is a need for action if, when the source is in normal use, a person may receive a dose from a single source that is more than one hundred times the global average background dose? These are different scenarios. Clarification of the meaning and intent of the sentence would be useful. 3. Justification ICRP proposal Justification is no longer a fundamental principle of protection. ICRP is applying its system of protection to practices that have been declared justified. Comments Justification is an established and accepted fundamental principle and any change must be explained. It is accepted that the responsibility for judging the justification of a practice usually falls on governments and their agencies, and that radiological protection considerations are only one input to the decision. However, that does not reduce its potential value as a fundamental principle. The justification principle is an important element in parts of the Australian legislation. Protective actions to avert dose in intervention situations must still be justified but justification of intervention is not explicitly addressed. It would be useful if the recommendations provided guidance on how intervention situations should be handled since the concepts of intervention and avertable doses are not used. ICRP proposal P18 states that justification is a prerequisite of the system of protection while P20 states that the system of protection may also apply in situations where the practice has not been declared justified. Comments Further clarification would be useful. 4. Exclusion ICRP proposal It is proposed that low doses and those that are not amenable to control be used as the basis for exclusion. This approach is applied to natural and artificial sources. Comments The proposed simplification is welcome. Additional clarification on the meaning of exclusion and how it is distinct from exemption would be useful. ICRP proposal Numerical values in terms of activity concentrations for exclusion are provided (Table S2 and 10). Comments The levels for artificial emitters seem to be the most restrictive of the values proposed by IAEA and for many isotopes these values might safely be exceeded. P206 – an unequivocal definition of “activity concentration” could be helpfully included here. 5. Exemption ICRP proposal Exemption is now regarded as a form of authorization and a regulatory matter. The need for activity concentration levels for practical application is proposed. Comments The need for changes to the approach given in ICRP 65 is not clear. The proposed use of activity concentration levels for practical purposes is welcome. 6. Quantities and units ICRP proposal Radiation weighted dose and RBE weighted absorbed dose are proposed. Comments The attempt to simplify the units is welcome. ICRP proposal Changes in radiation and tissue weighting factors are proposed. Comments The changes do not appear to have any significant safety implications. A considerable amount of work could be involved in making changes to the operational quantities. ICRP proposal The Commission is considering a new special name for radiation weighted dose so as to avoid the use of the name ‘Sievert’ for both radiation weighted dose and effective dose. Comments This is welcome and the introduction of this term should preferably be incorporated within the 2005 Recommendations. P41 (and elsewhere) – the word “fluctuations” could perhaps be usefully replaced by the word “variations”. P76 could be read as implying that epidemiological studies are the sole basis for an assessment of the RBE for other radiations. LET is mentioned in a number of places but there does not appear to be a clear explanation within the document as to what LET is? 7. Annual Limits of Intake ICRP proposal ALI values are explicitly not provided. Comments As the Commission itself notes, ALI values can be useful in various situations. Presumably, ICRP will continue to provide coefficients from which ALIs can be derived? Is ICRP resurrecting the concepts and information provided in ICRP 30? If so, this is welcome and the statement could be made clearer. 8. Changes in terminology ICRP proposal The replacement of the terms “deterministic effect” and “stochastic effect” by “tissue reaction” and “cancer development and inheritable disease” is proposed. Comments Any attempt to simplify the terminology is welcome and “tissue reactions” reads well and perhaps conveys a more relevant interpretation. The use of the term “cancer development and inheritable disease” might give the impression of equal weight/concern being applied to these two different effects when heritable effects comprise only a small component of the overall detriment. P111 – is it still legitimate to assume an adult working life to be between the ages of 20 to 64 and, as a consequence, are our lifetime dose expectations and associated calculations being unnecessarily cautious? ICRP proposal P113 states that the nominal risk coefficient given will tend to be an over-estimate of risks in the future. Comments Although the document argues this point later on it would be useful to include here an explanation of how this statement is legitimized. P117 – is the data which monitors IQ losses a sufficiently scientific and rigorous measurement for reference? 9. Types of worker ICRP proposal Workers in ‘controlled areas’ are categorised as a separate group of informed individuals. Other workers appear to be included in the group of general individuals, and treated as members of the public. Comments Most legislation treats workers exposed to radiation not directly related to their work as if they were members of the public. However, there is generally no distinction between those workers in controlled and those in supervised areas. There appears to be an implication is that workers working routinely in controlled areas are different from other workers with radiation? 10. Dose constraints and limits ICRP proposal The dose limits are unchanged from ICRP 60. The maximum dose constraint for workers is 20 mSv in a year (Table 7). Exceeding a dose constraint may be an offence, reflecting that their role has changed. Comments This appears to be a significant change. In ICRP 60 dose constraints were to be used prospectively for the optimization of protection: they were not regulatory limits. This implies that dose constraints are equivalent to current limits. 11. Optimization of protection ICRP proposal Optimization is now described as “broader than just considering the doses so as to assure safety culture”. Comments ICRP have previously stated that optimization of protection and ALARA are essentially the same thing. It is not clear what this broadening of the meaning of optimization means and further clarification would be useful. ICRP proposal P140 states that “The operator is responsible for providing input to the optimisation that will establish the authority for the operation of licensed practices, as well as for day-to-day optimisation.” Comments Clarification on the meaning and intent of this sentence would be useful. P194 could be read as promoting the use of ALARP rather than ALARA? 12. Radon ICRP proposal Radon is regarded as a controllable source. The maximum value of the action level in ICRP 65 is now the maximum constraint. Countries are to develop their own constraints and then, through optimization, ‘to arrive at the most applicable level at which to act’. Comments This appears to be a significant change. It is noted that countries establishing their own constraints and arriving at their own “most applicable level to act” is likely to result in considerable differences. The establishment of constraints and optimization of protection to find “the most applicable level” at which to act could take considerable effort. This appears to be the effect of the ‘blurring’ of the previous distinction between practices and interventions? 13. Dose constraints ICRP proposal A new emphasis on source-related dose constraints is proposed. The maximum dose constraint is 1 mSv in a year (the average annual dose limit). Comments The differences between the concept of the dose constraint for occupational exposure and that for members of the public could usefully be made clearer. The changes to the concept of constraint are likely to require revisions to regulatory guidance. Careful consideration of dose constraints for the public is needed. The value of 0.3 mSv in a year as a maximum dose constraint for discharges is not used in Table 7 but has gained some acceptance. 14. Optimization of protection ICRP proposal See occupational exposure. Disaggregation of doses resulting in a ‘dose matrix’ proposed. Comments Addressing stakeholder involvement is an ongoing effort. Further practical guidance in this area would be helpful. Further explanation and an example of the use of dose matrix would be of assistance. The concept that optimization of protection is reached when there is consensus needs further explanation. The term ‘stakeholder’ is often used but without a clear definition. It would be useful if ICRP further clarified who are the stakeholders and their various roles. 15. Radon in dwellings ICRP proposal A maximum constraint of 600 Bq.m-3 is proposed. National authorities are to establish constraints below this level. Countries are to develop their own constraints and then, through optimization, ‘to arrive at the most applicable level at which to act’. Comments The establishment of constraints and optimization of protection to find “the most applicable level” at which to act could take considerable effort. The need for changes to the approach given in ICRP 65 is not clear. Countries establishing their own constraints and arriving at their own “most applicable level to act” is likely to result in considerable differences. The levels referred to need to be clarified. 16. Critical group ICRP proposal Age-averaged effective dose coefficients and age-averaged habit data is proposed for the purpose of assessing compliance with the specified constraint. Comments This appears to be a pragmatic approach and could potentially simplify matters. 17. Dose constraints for workers ICRP proposal 100 mSv in a year dose constraint for emergency response proposed (Table 7). Comments This is a new feature and more explanation would be useful. The more conservative value of 100 mSv will have an impact on emergency arrangements and the necessity is not explained. 18. Dose constraints for public ICRP proposal 100 mSv in a year dose constraint for the public for evacuation and relocation and 20 mSv in a year for sheltering, iodine prophylaxis proposed (Table 7). Comments Again, the use of the dose constraints, which is new in the context of emergencies, needs more explanation: it is not clear to whom the dose constraints will apply in emergencies – is it emergency service providers or persons exposed as a result of their involvement in an emergency. The application of constraints to countermeasures, such as iodine prophylaxis, is also difficult to understand. The concept of avertable dose – which was seen as useful – appears to have been discarded. There is no obvious linkage between specific countermeasures and their effectiveness. 19. Potential exposures ICRP proposal Source-related ‘risk constraints’ proposed. Comments Further clarification is required. Examples of generic risk constraint values based on generalisations of normal occupational exposures would be useful. The generation of generic risk values for regulatory purposes could take considerable effort. ICRP proposal P236 appears to imply that probability assessments such as those used to justify extra engineered and other controls in reactors, for example, are of little benefit. Comments While this is may be correct, the text does not provide an alternative process for dealing with such matters. Is ICRP indicating that scenarios which have very low probabilities should not be assessed, despite the very significant consequences of the scenario? How does this approach compare with how other hazards are treated and is it consistent? 20. Justification ICRP proposal P19 states that “The medical use of radiation is a practice that should be justified, as is any other practice, although that justification lies more often with the profession rather than with government.” Comments This sentence requires clarification. “The medical use of radiation consists of a number of distinct practice types which should be justified, particularly on a patient by patient basis, and that justification lies more often with the profession rather than with government” is suggested as a replacement. ICRP proposal P19 states that “…a particular procedure falls on the relevant medical practitioners.” Comments The sentence “…a particular procedure in the diagnosis or treatment of a particular clinical condition falls on the relevant medical practitioners.” is suggested as a replacement. 21. Optimization Comments P189 could usefully include the need to engage in an optimization process in the delivery of radiation for medical purposes. 22. Dose constraints ICRP proposal Maximum dose constraint of 20 mSv in a year proposed (Table 7). Comments The maximum dose constraint of 20 mSv for comforters and carers is seemingly an increase and the necessity is not explained. If this is required, then it could sensibly have caveats added that state that this maximum would not be appropriate for all persons. S9 does not directly address medico-legal exposures or exposures for occupational health and safety reasons. P19 could usefully include mention of nurses and other non-medical persons who refer for radiographs. P220 could usefully include some of the quantitative information presented in P117 and at other points earlier in the document. P225, sentence 3 appears to confuse constraints and limits.