Addressing current knowledge gaps on radionuclide transfer to reptiles

Model intercomparison exercises have identified radionuclide transfer predictions as the greatest source of uncertainty in biota dose assessments. One wildlife group for which few transfer data exist is reptiles. Given that reptiles are an important, and often protected, component of many ecosystems and that assessments of radiation impact on ecosystems are becoming increasingly necessary due to the current nuclear renaissance, there is a need to further develop our current database on transfer to reptiles or find alternative approaches to estimate reptile transfer parameters. Three approaches that have the potential to increase the availability of parameters to predict radionuclide transfer to reptiles are the use of non-lethal sampling techniques, phylogenetic relationships and allometric relationships. Non-lethal sampling is an attractive long term option for deriving transfer parameters, but the derivation of phylogenetic and allometric relationships could provide ways of predicting transfer in the interim

Implementation of the Integrated Approach in Different Types of Exposure Scenarios

The ICRP recognises three types of exposure situations (planned, existing and emergency). In all three situations, the release of radionuclides into the natural environment leads to exposures of non-human biota, as well as the potential for exposures of the public. This paper describes how the key principles of the ICRP system of radiological protection apply to non-human biota and members of the public in each of these exposure situations. Current work in this area within ICRP Task Group (TG) 105 is highlighted. For example, how simplified numeric criteria may be used in planned exposure situations that are protective of both the public and non-human biota. In emergency exposure situations, the initial response will always be focused on human protection however, understanding the potential impacts of radionuclide releases on non-human biota will likely become important in terms of communication as governments and the public seek to understand the exposures that are occurring. For existing exposure situations, we need to better understand the potential impacts of radionuclides on animals and plants especially when deciding on protective actions. Understanding the comparative impacts from radiological, non-radiological and physical aspects is often important in managing remediating legacy sites. The TG is making use of case studies of how exposure situations have been managed in the past to provide additional guidance and advice for the protection of non-human biota

Demonstrating the use of a framework for risk-informed decisions with stakeholder engagement through case studies for NORM and nuclear legacy sites

The international community has come a long way in developing a consensus that the remediation and management of naturally occurring radioactive materials and nuclear legacy sites will benefit from the use of the framework for risk-informed decision-making. Such a framework should ideally integrate risk assessment and decision-making. The framework presented in this paper specifically addresses the needs and expectations in the wider socio-economic and environmental context, as well as a narrower human health context. The framework was demonstrated as part of the International Atomic Energy Agency’s second Modelling and Data for Radiological Impact Assessments Programme. Three case studies, which have used or could use this integrative approach, are used for illustration. The first concerns remediation from uranium mining activities at Beaverlodge Lake in northern Saskatchewan, Canada, engaging stakeholders (also called ‘interested parties’) in the decision-making process on further options. The second case study suggests how decision analysis could support the selection of the best option for waste disposal for uranium ore processing at Žirovski vrh, Slovenia, taking into account a potential landslide and migration of waste throughout the adjacent valley in the event of flooding. The third case study presents the process and results of radiological safety assessment of the Kepkensberg sludge basin in Tessenderlo area, Belgium both before and after the disposal of material from remediation of the nearby Winterbeek River. It illustrates how such assessments could interface with decision analysis for the purpose of supporting the regulatory decisions related to future approval of a waste disposal option. Results show that formal stakeholder engagement in decision analysis provides a strong contribution to objective, robust, and transparent decision-making not only for radiation protection area but also in others where health and environmental impacts are of concern. A number of recommendations for future work have also been made

Modelling the exposure of wildlife to radiation: key findings and activities of IAEA working groups

The International Atomic Energy Agency (IAEA) established the Biota Working Group (BWG) as part of its Environmental Modelling for Radiation Safety (EMRAS) programme in 2004 (http://www-ns.iaea.org/projects/emras/emras-biota-wg.htm). At that time both the IAEA and the International Commission on Radiological Protection (ICRP) were addressing environmental protection (i.e. protection of non-human biota or wildlife) within the on-going revisions to the Basic Safety Standards and Recommendations respectively. Furthermore, some countries (e.g. the USA, UK) were already conducting assessments in accordance with national guidelines. Consequently, a number of assessment frameworks/models had been or were being developed. The BWG was established recognising these developments and the need to improve Member State’s capabilities with respect to protection of the environment from ionizing radiation. The work of the BWG was continued within the IAEA’s EMRAS II programme by the Biota Modelling Group (http://wwwns. iaea.org/projects/emras/emras2/working-groups/working-group-four.asp)

Making the most of what we have: Application of extrapolation approaches in radioecological wildlife transfer models

© 2015 The Authors. We will never have data to populate all of the potential radioecological modelling parameters required for wildlife assessments. Therefore, we need robust extrapolation approaches which allow us to make best use of our available knowledge. This paper reviews and, in some cases, develops, tests and validates some of the suggested extrapolation approaches.The concentration ratio (CRproduct-diet or CRwo-diet) is shown to be a generic (trans-species) parameter which should enable the more abundant data for farm animals to be applied to wild species.An allometric model for predicting the biological half-life of radionuclides in vertebrates is further tested and generally shown to perform acceptably. However, to fully exploit allometry we need to understand why some elements do not scale to expected values.For aquatic ecosystems, the relationship between log10(a) (a parameter from the allometric relationship for the organism-water concentration ratio) and log(Kd) presents a potential opportunity to estimate concentration ratios using Kd values.An alternative approach to the CRwo-media model proposed for estimating the transfer of radionuclides to freshwater fish is used to satisfactorily predict activity concentrations in fish of different species from three lakes. We recommend that this approach (REML modelling) be further investigated and developed for other radionuclides and across a wider range of organisms and ecosystems.Ecological stoichiometry shows potential as an extrapolation method in radioecology, either from one element to another or from one species to another.Although some of the approaches considered require further development and testing, we demonstrate the potential to significantly improve predictions of radionuclide transfer to wildlife by making better use of available data