Comments on Federation of Electric Power Companies iJAPANj on the draft ICRP 2006 Recommendations
Nuclear power is a very useful energy for our society. For us to benefit from it, a balance between its benefits and acceptable risks is important.
The draft new Recommendations imposes dose constraints below the dose limits to be applied or used in all situations, despite the absence of new findings indicating health effects requiring an upward revision of the previous risk assessments. This has raised concern among operators in Japan that if the new Recommendations are enacted into national regulations, both dose constraints and dose limits would exist simultaneously particularly in planned situations, possibly resulting in (misleading) double regulations. This could eventually compromise current regulations based on the 1990 Recommendations and hamper optimization efforts by operators.
Optimization of protection against occupational exposure requires effort by site staff (operators) commensurate with the site (source) conditions before adequate protection can be achieved. Though risks may be invariable, the draft new Recommendations requiring all countries to change their regulatory frameworks, may invite confusion at every site without providing real benefits to anyone. Regarding the optimization of protection against public exposure as well, we also want the Recommendations be refined to avoid the imposition of uniform regulations and to allow flexible responses suited to needs for optimizing in different national contexts or exposure scenarios.
Thus, although it is important for the basic concept of radiological protection to be delineated by the ICRP, flexible application on a country-by-country or industry-by-industry basis should be permitted provided that international consistency is ensured. The new Recommendations ought to take into consideration a country like Japan, where rigorous control has already been established under national regulations; hence its text should be tailored accordingly, so that the officials concerned can readily appreciate that they do not necessarily have to adopt the new Recommendations into their national laws.
On the other hand, we appreciate that new findings such as biological data are reflected and warnings as to the abuse of collective doses incorporated in the draft new Recommendations.
We expect the ICRP to endeavor to avoid possible confusion that the new Recommendations may cause to nuclear power developments and nuclear power sites. We, therefore, request further scrutiny by the ICRP of the numerous comments from various countries concerning the optimization process, dose constraints, the definition of a single source, the relationship with dose limits, and the scope to be covered by regulations, which however, do not require immediate conclusions as presented by Chairman Holm at the OECD/NEA Asia Conference.
Based on the above general remarks, we have focused particular attention on the following draft new Recommendation issues:
(1) Dose constraints
‡@ Selection of dose constraints for occupational exposure
At a nuclear power station, work plans are developed and dose control implemented for the respective periodic inspections and for each operation. It goes without saying that doses vary according to the state of the plant and depending on whether or not there are special operations. Therefore, optimization can only be achieved through on-site decision-making. Dose constraints are not the kind of values that can be defined in a uniform manner by regulatory authorities.
Publ.75 (para. 51) which contains recommended general principles pertaining to radiological protection for workers, states that "As a general rule, it would be more appropriate for the regulators to encourage the development of constraints within particular industries and organizational groupings, subject to regulatory oversights, than to stipulate values of constraints."
Therefore, in the section concerning the dose constraints for occupational exposure (5.8.4), it should be laid down that operators are allowed, if necessary, to select values adapted to given situations and use them as target values for optimization.
‡A Selection of dose constraints for public exposure
Fixed values such as 0.1 or 0.3 mSv/year should not be uniformly applied, but rather it should be possible to discretionary select optional values suited to specific situations (it ought to be possible to differentiate according to national contexts or exposure scenarios). Also, in order to prevent the use of constraints corresponding to an extremely low dose range, it should be stipulated in the section (5.8.6) concerning dose constraints for public exposure that no doses equal to or below one-tenth of natural BG radiation (0.1 mSV/year or less) should be treated as constraints.
‡B Effective dose bands
The values of 100 mSv, 20 mSv and 1 mSv listed in Table 4 tend to be construed as requiring doses to be confined in these boundaries. The emergency dose limit "500 mSv," the occupational exposure dose limit "50 mSv" and the public exposure dose limit "5 mSv" specified in the 1990 Recommendations should be introduced as prescribed values of protection criteria, so as to provide a gradation scale of dose limits from which values suited to given situations can be selected on a case-by-case basis.
(2) Definition of a single source
With respect to single sources subject to dose constraints to be applied to all situations, the Recommendations should only provide a conceptual definition to allow for flexible case-by-case treatment. What is important now is to accumulate case data on the actual use of single sources. This issue requires further discussion.
(3) Protection of the environment
Protection of the environment is acceptable as an evaluation method to address the effects on animals and vegetation, but there is concern that it may lead to excessively strict regulations to protect animals and vegetation. We expect your inquiries into this issue to involve careful discussions with adequate consideration for scientific data-based comparison with other factors (environmental chemicals, etc.) and criteria in actual use, with close attention to reaching a balance between risks and benefits.
(4) Collective doses
The draft new Recommendation states (para. 147), "The computation of cancer deaths based on collective doses involving trivial exposures to large populations is not reasonable and should be avoided." We support this concept regarding the application of collective doses, though this concept, in fact, has been neglected. Based on the background level of natural radiation, "a few mSv/year" should be adopted as the lower limit applicable to collective doses, and a better defined application scope should be laid down.
(5) Cancer risks
It is stated in the draft new Recommendations (para. 55) that "c..supports the view that in the low dose range under 100 mSv it is scientifically reasonable to assume that the increase in the incidence of cancer or hereditary effects will rise in direct proportion to an increase in the absorbed dosec.." This may lead to the false impression that the substantial uncertainties associated with the law dose range under 100 mSv have been resolved both epidemiologically and biologically although no epidemiological and biological data obtained hitherto has provided compete answers to those uncertainties.
In view of the fact that LNT has set a conservative range for radiological protection where no risk may be detected, the above statement should be revised as follows: "c..supports the view that in the low dose range under 100 mSv it is conservative and, from a regulatory point of view, reasonable to assume that the increase in the incidence of cancer or hereditary effects will rise in direct proportion to an increase in the absorbed dosec..."