Optimisation of radiological protection

Draft document: Optimisation of radiological protection
Submitted by Ted Lazo, NEA
Commenting on behalf of the organisation

Comments on the ICRP draft "foundation documents", submitted to NEA CRPPH by the Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit. 1. Assessing Dose of the Representative Individual, 2. Reference Animals and Plants and 3. Optimisation of Radiological Protection. BMU-RS III 2 1. Assessing Dose of the Representative Individual for the Purpose of Radiation Protection of the Public Section 9 of the Introduction on page 2 states that guidance for the protection of individuals in the case of disposal of long-lived radioactive waste is provided in ICRP Publication 81. It remains unclear whether the document under consideration is thus to be regarded as supplementation to ICRP 81 or whether long-term protection of individuals against impacts from disposal has already been regulated adequately in ICRP 81. This clarification is necessary. Should this document be regarded as supplementary regulation, the explanations in the individual sections would have to be discussed and assessed in detail. 2. The Concept and Use of Reference Animals and Plants for the Purpose of Environmental Protection The report does not clearly show in which way the presented concept shall be applied with regard to the disposal of radioactive wastes and, in particular, the demonstration of long-term safety of repositories. If such an application should be intended, it remains unclear for which period of time during the post-operational phase this approach shall be followed. GRS points out that the long-term safety analyses provide potential contaminant concentrations in the groundwater for very long periods of time. The individual doses or risks calculated from these analysis results are not to be understood as a quantitative prognosis of a radiological exposure but only as indicators for the isolation capacity of a repository. The approach generally applied in the safety demonstrations at present, i. e. to assess the safety analyses by means of the safety indicators “dose” or “risk” and other indicators, would have to be supplemented by indicators of the reference biosphere. In this respect, the following issues should also be clarified: • How realistically can the natural and the additional radiation exposures of these reference organisms be determined? • To which extent can the postulated dose-effect relations for these organisms be extrapolated? • Which impacts are tolerable? Which assessment criteria have to be applied? Further, such changes in the biosphere are to be expected when considering very long periods of time that a reference biosphere with reference animals and reference plants cannot be defined on a scientifically sound basis. For example, dry-out or flooding of the habitat, heat or cold, or a climate change as occurred periodically in the past contribute increasingly to risks for individual species and will probably contribute to the extinction of some species in their habitats but also to a recolonisation by other organisms better adapted to the new environmental conditions. Thus, before introducing such an approach for the assessment of the safety of a repository in the post-operational phase, the question has to be answered which reliable contribution it can provide for the assessment of the safety of a repository and, in particular, for long periods of time. Assessment parameters regarding radiological exposures of non-human biota can only be indicators for the assessment of the isolation capacity during the long-term phase (as is already the case for individual dose and risk). Therefore, it is not to be expected that their determination will provide additional information on the safety functions of a repository. But it is exactly the assessment and improvement of these safety functions the research and development work should concentrate on. 3. Optimisation of Radiological Protection In this report, the disposal of radioactive wastes is not addressed explicitly. In this respect, it remains unclear whether it should be taken into account in the considerations. The report is strongly based on the ICRP 82 recommendations to substantiate the optimisation process described. ICRP 82, in turn, explicitly excludes the disposal of radioactive wastes. Therefore, it has to be clarified whether the proposal presented includes the disposal of radioactive wastes.