|STUK Comments, Part 1 of 2
1. Principal Remarks
1.1. Connection of the new draft document to the old recommendations
The proposed draft of the new ICRP 2005 Recommendations presumes good knowledge of the old ICRP Recommendations, and therefore it is not a good, basic, radiation safety document. It should be clearly indicated whether the 2005 Recommendations is expected to be a stand alone document or whether it should be read together with the 1991 recommendations. The first alternative is preferable, although it would require a lot of redrafting.
1.2. Justification principle
The present draft does not anymore discuss the justification principle, except very briefly (items 8, 18, 20) and specifically only in relationship with medical exposures. Combining this with the intro-duction of the concept of minimum dose constraint (item 164) raises the question of whether all prac-tices with low doses will then be justified. Justification is one of the pillars of radiation safety, and needs greater concern.
1.3 Application of the exclusion levels
Artificial radionuclides: In paragraph 8.1 there is a reference to the IAEA Safety Guide No. RS-G-1.7 gApplication of the concepts of exclusion, exemption and clearanceh. The values of activity con-centration of the Safety Guide are not intended to be applied to the control of radioactive discharges of liquid and airborne effluents from authorised practices, or to radioactive residues in the environ-ment. Accordingly, the values do not exclude any material below the given levels from being radio-active material and from a radiation protection system. They do not define what is radioactive. The general radiation protection system recommended by ICRP should also follow the same line of think-ing and refrain from defining numerical concentration values to define what is to be considered ra-dioactive. A further minor comment: in paragraph 8.1, it is stated that the CODEX recommendations of activity concentrations in foodstuffs have been revised in 2004. The revision process is, however, not yet finalised.
Natural radionuclides: There are circumstances where the application of the suggested exclusion values for natural radionuclides (Table S2) will lead to such high exposures that they can not be ex-cluded from the scope of some sort of regulatory control. For example, it can be easily calculated that in a block of apartments made of concrete, complying with the suggested values (1 Bq/g of Th-232 and U-238 respectively, and 10 Bq/g of K-40), the external gamma dose rate inside the building will be over 2 ƒÊSv/h. With an annual occupancy time of 7000 hours this will result in way over 10 mSv/a (effective dose) to an inhabitant! Additional doses would also be caused by radon released from the material. Allowing the construction of such buildings without any limitations would be in clear con-tradiction with Table S1, for example.
When the IAEA Safety Guide RS-G-1.7 was prepared, such situations were considered and taken into account appropriately. Paragraph 5.1 of the Guide reads:
gIt is usually unnecessary to regulate radioactive material in activity concentrations below the val-ues given in Table 1. However, there are some situations (such as the use of some building materials containing natural radionuclides) for which exposures from materials due to radionuclides with ac-tivity concentrations below those given in Table 1 would necessitate consideration by the regulatory body for some types of regulatory control. Regulatory bodies should retain the authority to investi-gate such situations and to take whatever action is considered necessary.h
The ICRP should consider including a similar statement in the 2005 Recommendations.
1.4 Dose constraints
The new draft ICRP Recommendations emphasize the responsibility of the regulatory authority to set dose constraints. The optimisation should not become too administrative. It could easily lead to a situation where the management of a practice is satisfied when these set constraints are not exceeded, even though optimisation under the constraints should also be executed.
In the new draft, it is said (item 136) that sometimes also the management of a practice could set con-straints for themselves. This leads to a possibility for confusion as the same name is used for values set by the authority and for those set by the management itself.
The ICRP should make a clear distinction (preferably by using different names) between values set by the regulatory authority and any values set by the management of a practice for their own optimi-sation purposes.
The attempt to fit the concept of action level for radon (ICRP 65) under the umbrella of gconstraintsh leads to confusion. As described in items 179-180, in case of radon, optimisation takes place only as part of the process of setting an appropriate gnational constrainth (that is, an action level). Once this gconstrainth is set, there is no optimisation in individual cases that are under this value. This is totally different from how all the other gconstraintsh are used (that is, optimisation in individual cases when under the constraint level). As these are two totally different concepts, it is very confusing to use the same name for both of them. The ICRP should consider preserving the concept of action level for radon, because it has been widely accepted and has turned out to be a very clear and practical con-cept for radiation protection work.
1.5 Collective dose
The concept of Lcollective doseL (effective or equivalent), defined as the mean individual dose multi-plied with the number of exposed individuals, has been downplayed in the present draft. In the sum-mary it is not mentioned at all. However, it is still an important tool for expressing the total detriment in any situation where a large number of individuals are exposed to low doses. The statement (item 200) ga large dose to a small number of people is not the same as a small dose to a large number of peopleh is only true for situations where the magnitude of individual doses is a cause of concern. It is not relevant, however, for cases in which all individual doses are well below any limits and the indi-vidual risks are low, but there remains a need to consider the total detriment. For all such situations, the collective dose continues to be a relevant quantity and, according to the LNT model, is a good measure of the total harm. It is not true that collective dose excessively aggregates information in these cases. In our experience, collective dose is also a very useful concept in explaining radiation detriment and protection principles to non-professionals, political decision makers, for example, and its use for this purpose will continue. The concept should also be retained and treated in the sum-mary. The statement in item 118 of ICRP 60, gThe collective effective dose is an adequate repre-sentation of the collective detrimenth, is still valid for administrative decision making, for example, and should be retained.
1.6 Effective dose
The effective dose, as a quantity, should be defined as clearly and explicitly as possible. This clarity would need to be further improved in the present draft, especially for the special cases discussed in the detailed remarks below: (i) the case of the exposed people belonging to just one gender and (ii) the exposed groups having different age distributions (or the exposed person being a child or an adult).