Submitted by Daniel Storch, Federal Office for Public Health Switzerland Commenting on behalf of the organisation
The Federal Office for Public Health Switzerland acknowledges the usefulness of the document and the integration of recommendations (ICRP 109 and 111) from the different phases into a single document.
Comments:
2.1 Timeline for managing a nuclear incident We deplore that the ICRP do not adopt the same subdivisions to describe the timing of an accident as the IAEA (Arrangements for the Termination of a Nuclear or Radiological Emergency).
The document introduces the concept of Early and Intermediate phases of Emergency Response, with the Early phase being (11) “characterised as the period during which the radionuclides are released into the environment.” “The intermediate phase of the emergency response (12) starts when the source of the release has been stabilized and further significant accidental releases are unlikely”. The definitions of the different phases according to the ICRP are therefore mainly related to the “state” of the source. In the IAEA documents however, the definitions of the different phases are related to the protective actions: urgent protective action during the urgent phase and early protective action (such as relocation) in the early phase.
In Section 3.1: Characteristics of the early and intermediate phases however, ICRP relates the early phase to the “urgent protective action” (89) and the introduction of “other less urgent protective actions” (such as temporary relocation-see 3.4.2.1) to the intermediate phase (90). Consequently, the ICRP’s early phase seems to correspond to IAEA’s urgent phase and the ICRP intermediate phase to the IAEA’s early phase. However, this is not consistent with the prior definitions of the phases, which are based on the state of the source. For example in the case of the accident at the Fukushima NPP, the releases lasted for weeks and as stated in the document urgent protective actions such as evacuation or sheltering are short term protective actions that have to be replaced by other “early” protective action within 48 h to 72 h (or up to one week for evacuation). Depending on the nature and scale of the event, relocation could therefore take place before the end of the release. These different definitions and statements cause a lot of confusion.
We therefore suggest that the ICRP reconsider their definitions of the phases and recommend that the definitions be in good agreement with those of the IAEA, in particular when dealing with the consequences of a large nuclear accident.
The early phase as defined by the ICRP should at least be renamed in order not to be mixed with the “Early phase” according to IAEA as both phases are related to a different stage after the initial accident. For decision makers, defining subdivisions on the base of the protective measures as proposed by the IAEA (urgent protective measure = urgent phase and early protective measure such as relocation in the early phase) is less scenario dependent and easier to delimit and to handle.
Figure 2.1 shows the relationship between the Emergency Exposure situation and the Existing Exposure situation as a continuous transition. The use of a color gradient to show the transition between the emergency and existing exposure situation is confusing. Of course these exposures may coexist in different geographical areas, but within an area the transition from an emergency exposure situation to an existing exposition situation is not a continuous process but a political decision (3.5.2 and 3.5.3) (Termination)
The figure should be adapted to better reflect this point.
2.3.3 Optimization and the use of reference levels (80) For people living in long-term contaminated areas following the emergency response, the Commission recommends that the reference level should be selected within or below the Commission’s recommended 1–20-mSv band taking into account the actual distribution of doses in the population and the tolerability of risk for the long-lasting existing exposure situations, and would not generally need to exceed 10 mSv per year, with the objective to reduce exposure progressively to levels on the order of 1 mSv per year.
Past experiences have shown that reference levels must be flexible and should be selected depending on prevailing circumstances and the long-term view in the aftermath of a large accident with the whole purpose of doing more good than harm. The concept of a reference level whose value is to be set, as low as reasonably achievable, within a predefined band depending on the situation makes sense and corresponds well to the notion of optimization.
Apart from a more complex system with the introduction of an additional value (unknown until now in the radiation protection system), compared to the professional (recovery responder), this recommendation does not provide a significant improvement in protection.
We agree that a value above 10 mSv per year as a reference level for the protection of the public over several years for people living in long term contaminated areas following the emergency response is not appropriate. But if the concept of “the reference level” is understood and properly implemented, the optimization process will allow the reference level to be lowered regularly to accompany the improvement in the radiological situation. Therefore the ICRP should give more importance to the process of defining and re-evaluating the value of the reference level during the long-term phase rather than restricting the band to the lower value from the beginning of the process (of optimization). Not allowing a reference value of 20 mSv/year just after the termination of the emergency response after a large nuclear accident could be contraproductive. For example, in countries that have implemented the 20 mSv-100 mSv band for emergency purposes (replaced here by < 100 mSv), setting a minimal value of 10 mSv/year for the reference level for the protection of the public could prolong the emergency exposure situation unnecessarily.
Arguments like those in (178) “Selecting a value that is too high can be of little incentive to engage authorities and other stakeholders in rehabilitation of their living conditions” should not be taken into account without considering the risk that it may lead to a loss of confidence in the reference level concept and the presumption that the ICRP do not trust the (implementation of the) optimization principle.
The present publication seeks to clarify the Commission's recommendation on the choice of dose bands in the different exposure situations (ICRP 103). The concept of the reference level based on the optimization principle is not easy to explain. But restricting the dose band or abandoning the free choice of a value in a dose band tends to reinforce the misunderstanding in the implementation of reference level mentioned in (74), as it “looks like” the introduction of a dose limit.
Especially in the case of a severe accident at a nuclear power plant, the maximum freedom in the choice of the reference value must be preserved.
Table 6.1. Reference levels for optimization of the protection of people in the case of nuclear accidents.
The concept of distinguishing between on-site and off-site is a promising approach, but may be complicated in view of the vague definition. For instance, nuclear power plants consist of several facilities. ‘On-site’ may refer to one particular reactor unit, a storage building or the entire power plant.
We further recommend that table 3.1 and table 6.1, which do not seem to be entirely consistent, be merged into one table for reasons of clarity and comprehensibility.