The Optimisation of Radiological Protection
1. The document is somewhat unbalanced. While the conceptual and philosophical aspects of the principle of optimisation are dealt with very rigorously and in great detail, the problems associated with the practical application of this principle are little more than set out, with hardly any detailed development.
Thus, for example, the “dose matrix” (paragraphs 72 and 73) constitutes a concept that (in view of its novelty) may have important implications as regards the practical application of the principle of optimisation, despite which it is addressed in the document from an exclusively theoretical perspective, without going into practical details that might be very relevant. For this reason, the SEPR feels that an Annex should be included with a practical example of the application of the aforementioned dose matrix.
2. In the Executive Summary (page 7) it is stated that: “The endpoint of the process is expressed by the Commission as the designation, by the decision maker, of the most appropriate protection option under the prevailing circumstances, duly taking into account the views developed by stakeholders”
Nevertheless, throughout the document important nuances are repeatedly included in relation to the degree of involvement of the stakeholders in the process of optimisation. Thus, it may be deduced from the document that:
- The opinion of the stakeholders constitutes a highly valuable element in decision-making in complex situations, in which social, economic and political considerations prevail (for example, prolonged exposure of members of the public, etc.).
- The opinion of the stakeholders is not so relevant in less complex situations (exposure of professionally exposed workers), since in fact in such cases stakeholder involvement may be reduced (Annex A1, section 4) to simple dialogue between the operator and the workers.
In this context, the SEPR considers that it is strictly necessary for the Executive Summary to include a paragraph clarifying that the degree of participation of the stakeholders in the process of optimisation should be conditioned by the radiological complexity of the situation, by the complexity of decision-making and by the level of radiological risk associated with the situation.
3. Paragraph 25 (and figure 1) establishes that optimisation is a unique process, the systematics of which are applicable, adhering to one same scheme, to any type of situation (planned, existing, emergencies) and to any type of exposure (workers and public). This approach is perfectly valid from a conceptual point of view; however, from the perspective of implementation it might give rise to errors in interpretation and to conflicting situations.
In this respect, the SEPR reiterates what has been stated above as regards the need to keep a clear distinction between the system of protection applicable to situations under control (practices) and the system of protection applicable to emergency or “de facto” situations (interventions). This distinction, which the SEPR considers to be one of the most valuable contributions made by the recommendations of ICRP-60, should not be lost in future recommendations.
4. Special emphasis is placed in the document on the difficulties associated with optimisation in situations implying prolonged exposure (in space and time) of members of the public; it is precisely these difficulties that leads the ICRP to introduce novelty elements (stakeholder involvement, disaggregation of the distribution of individual doses, limited use of collective dose, qualitative factors) with respect to the approach adopted in previous recommendations.
However, the SEPR does not consider it suitable that these new elements aiding decision-making with regard to optimisation (which will undoubtedly be useful in the area of public exposure) should be analogously applied to exposure of the workers, where the difficulties involved are not so great (and where, for example, the collective dose should continue to be a determining factor in decision-making in relation to optimisation).
Indeed, and as indicated in Annex A1 (section 2), the principle of optimisation is well implemented in the area of exposure of the workers (occupational exposures are optimised below limits by proper planning, preparing, implementing, and reviewing). If this is the case, there is no justification for the ICRP’s considering the introduction of new elements for assessment, which will do little more than (unnecessarily) disturb a system that operates correctly.
5. The document introduces important terminological changes with respect to previous ICRP recommendations. Thus, for example:
- The term “dose constraint” is used (instead of “intervention level”) to refer to the restrictions on individual doses applicable to both emergency situations and to controllable existing situations.
- The term “dose constraint” is used (instead of “action level”) to refer to the restrictions on individual doses applicable to exposure to radon.
The SEPR reiterates a comment made above in the sense that the introduction of new terms to refer to concepts already in use and widely accepted (such as “intervention levels” for emergencies and “action levels” for radon) should be avoided unless they are strictly necessary, since this may lead to unnecessary conflicting situations.
Furthermore, the SEPR considers it questionable that one same term (dose constraint) should be used to refer to dose restrictions applicable to situations (planned exposures, emergency exposures, controllable existing exposures, radon exposures) whose management implies significant differences from the point of view of radiological protection. The use of one same term for situations that are so different from the practical point of view will undoubtedly cause confusion and errors in interpretation.
6. Optimisation is repeatedly associated with the concept of the safety culture. The SEPR considers that such association would require explanations additional to those presented in the document.
- There should be a definition of what is understood by the safety culture, since there is no universally accepted definition of the concept.
- There should be a definition of which elements, from among those constituting what is known as the safety culture, determine the efficient implementation of the principle of optimisation.
7. Optimisation is repeatedly associated with the concept of BAT (Best Available Technology), in all cases in relation to emissions to the environment. The SEPR considers this association to be questionable, since the starting points are different for the two concepts:
- The objective of the optimisation of radiological protection is to achieve the best level of protection under the prevailing circumstances.
- The objective of the concept of BAT is to use the best available technology to reduce emissions to levels “close to zero”, this being associated more with the concept of minimisation than with optimisation.
In this context, associating optimisation with the BAT concept might not be consistent with one of the principles established in the document (paragraph 56): “The exclusion levels, as defined in 2005 Recommendations, should not be considered as a relevant end point to optimisation”
8. Paragraph 73 provides criteria-related standards for the prioritisation of the elements that make up the dose matrix (relative weights). The SEPR considers that the prioritisation criterion established (magnitude of individual mean dose) is appropriate only for situations in which there are important differences between the individual mean doses of the different population groups. These differences may not be relevant in certain situations (planned exposures) for which different prioritisation criteria should be established.
9. Throughout the document there are certain statements that the SEPR considers to be questionable an that might, in certain cases, lead to incorrect interpretation:
- Page 28 (paragraph 59): “In the case of existing situations, including those arising from emergencies or past activities, the optimisation aims at the progressive reduction of individual doses towards the levels that are applicable for normal situations”.
This sentence might be interpreted mistakenly, in the sense that the dose restrictions applicable to emergency situations should necessarily approximate to the typical values in normal situations, which contradicts the essence of optimisation (better level of protection under the prevailing circumstances)
- Page 30 (paragraph 79): “Except in cases of regulatory violation, it is not the role of the regulator to focus on specific outcomes for a particular situation, but rather on processes, procedures and judgements”
At least in the field of occupational exposure, the policy applied to date by our regulatory authority, based on meticulous analysis of the results obtained (occupational doses) for each particular situation, has proven to be effective and, therefore, the analysis of the results should continue to be a basic element when evaluating the degree of implementation of the principle of optimisation.
- Page 38 (section 2.4): “Workers exposed to natural radiation should be given the same level of optimised protection as those exposed to artificial radiation.
This sentence might be erroneously interpreted as meaning that workers exposed to natural radiation should have applied to them a protection system similar (with similar dose restrictions) to that applied to professionally exposed workers at nuclear and radioactive facilities.