Browsing by Author "Copplestone, D"

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    Biota dose assessment for environmental radiotracer releases in aquatic environments
    (Australian Nuclear Science and Technology Organisation, 2012-10-17) Hughes, CE; Johansen, MP; Wilson, RC; Copplestone, D; Vives i Batlle, J
    The intentional release of short lived radioisotopes to trace transport and partitioning processes in the environment has been in decline in recent decades due to negative regulatory and public perceptions of the associated risks. Radiotracing is subject to significant regulatory requirements; in some jurisdictions one of these requirements is to demonstrate that radiation exposure to ecosystems is limited to ensure protection of populations of species. Radiation exposures from radiotracer studies are localised, transient and infrequent by nature, making it difficult to apply guidelines and biota dose assessment tools that are designed for chronic and widespread exposure scenarios. We will discuss the limitations of available guidelines and dose assessment methodologies when applied to radiotracer studies. A range of case studies for biota dose assessment will be presented using a variety of available tools including the ERICA Assessment Tool, the methodology of Copplestone et al. (2001) and a dynamic dose assessment model (Vives I Batlle et al., 2008). These case studies demonstrate that steady state, spatial homogeneity and bioavailability assumptions inherent in available dose assessment tools may lead to an over-estimate of dose to biota from radiotracer studies, and that many radiotracer studies can be conducted with minimal dose to biota.
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    Ensuring robust radiological risk assessment for wildlife: insights from the International Atomic Energy Agency EMRAS and MODARIA programmes
    (Published on behalf of the Society for Radiological Protection by IOP Publishing Limited, 2022-05-03) Beresford, NA; Beaugelin-Seiller, K; Barnett, CL; Brown, JE; Caffrey, EA; Johansen, MP; Melintescu, A; Ruedig, E; Vandenhove, H; Vives i Batlle, J; Wood, MD; Yankovich, TL; Copplestone, D
    In response to changing international recommendations and national requirements, a number of assessment approaches, and associated tools and models, have been developed over the last circa 20 years to assess radiological risk to wildlife. In this paper, we summarise international intercomparison exercises and scenario applications of available radiological assessment models for wildlife to aid future model users and those such as regulators who interpret assessments. Through our studies, we have assessed the fitness for purpose of various models and tools, identified the major sources of uncertainty and made recommendations on how the models and tools can best be applied to suit the purposes of an assessment. We conclude that the commonly used tiered or graded assessment tools are generally fit for purpose for conducting screening-level assessments of radiological impacts to wildlife. Radiological protection of the environment (or wildlife) is still a relatively new development within the overall system of radiation protection and environmental assessment approaches are continuing to develop. Given that some new/developing approaches differ considerably from the more established models/tools and there is an increasing international interest in developing approaches that support the effective regulation of multiple stressors (including radiation), we recommend the continuation of coordinated international programmes for model development, intercomparison and scenario testing. © 2022 Society for Radiological Protection.
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    Environmental impact of radiotracer studies: biota dose assessment
    (Tous droits réservés., 2014-10-13) Hughes, CE; Johansen, MP; Wilson, RC; Copplestone, D; Vives i Batlle, J
    The intentional release of short lived radioisotopes to trace transport and partitioning processes in the environment has been in decline in recent decades due to negative regulatory and public perceptions of the associated risks. Radiotracing is subject to significant regulatory requirements; in some jurisdictions one of these requirements is to demonstrate that radiation exposure to ecosystems is limited to ensure protection of populations of species. Radiation exposures from radiotracer studies are localised, transient and infrequent by nature, making it difficult to apply guidelines and biota dose assessment tools that are designed for chronic and widespread exposure scenarios. We will discuss the limitations of available guidelines and dose assessment methodologies when applied to radiotracer studies. A range of case studies for biota dose assessment will be presented using a variety of available tools including the ERICA Assessment Tool, the methodology of Copplestone et al. (2001) and a dynamic dose assessment model (Vives I Batlle et al., 2008). These case studies demonstrate that steady state, spatial homogeneity and bioavailability assumptions inherent in available dose assessment tools may lead to an over-estimate of dose to biota from radiotracer studies, and that many radiotracer studies can be conducted with minimal dose to biota.
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    The estimation of absorbed dose rates for non-human biota: an extended inter-comparison
    (Springer, 2011-05-01) Vives i Batlle, J; Beaugelin-Seiller, K; Beresford, NA; Copplestone, D; Horyna, J; Hosseini, A; Johansen, MP; Kamboj, S; Keum, DK; Kurosawa, N; Newsome, L; Olysaegers, G; Vandenhove, H; Ryufuku, S; Lynch, SV; Wood, MD; Yu, C
    An exercise to compare 10 approaches for the calculation of unweighted whole-body absorbed dose rates was conducted for 74 radionuclides and five of the ICRP's Reference Animals and Plants, or RAPs (duck, frog, flatfish egg, rat and elongated earthworm), selected for this exercise to cover a range of body sizes, dimensions and exposure scenarios. Results were analysed using a non-parametric method requiring no specific hypotheses about the statistical distribution of data. The obtained unweighted absorbed dose rates for internal exposure compare well between the different approaches, with 70% of the results falling within a range of variation of +/- 20%. The variation is greater for external exposure, although 90% of the estimates are within an order of magnitude of one another. There are some discernible patterns where specific models over- or under-predicted. These are explained based on the methodological differences including number of daughter products included in the calculation of dose rate for a parent nuclide; source-target geometry; databases for discrete energy and yield of radionuclides; rounding errors in integration algorithms; and intrinsic differences in calculation methods. For certain radionuclides, these factors combine to generate systematic variations between approaches. Overall, the technique chosen to interpret the data enabled methodological differences in dosimetry calculations to be quantified and compared, allowing the identification of common issues between different approaches and providing greater assurance on the fundamental dose conversion coefficient approaches used in available models for assessing radiological effects to biota. © 2011, Springer.
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    The IAEA handbook on radionuclide transfer to wildlife
    (Elsevier B.V., 2013-07-01) Howard, BJ; Beresford, NA; Copplestone, D; Telleria, D; Proehl, G; Fesenko, S; Jeffree, RA; Yankovich, TL; Brown, JE; Higley, K; Johansen, MP; Mulye, H; Vandenhove, H; Gashchakk, S; Wood, MD; Takatam, H; Andersson, P; Dale, P; Ryan, J; Bollhöfer, A; Doering, C; Barnett, CL; Wells, C
    An IAEA handbook presenting transfer parameter values for wildlife has recently been produced. Concentration ratios (CRwo-media) between the whole organism (fresh weight) and either soil (dry weight) or water were collated for a range of wildlife groups (classified taxonomically and by feeding strategy) in terrestrial, freshwater, marine and brackish generic ecosystems. The data have been compiled in an on line database, which will continue to be updated in the future providing the basis for subsequent revision of the Wildlife TRS values. An overview of the compilation and analysis, and discussion of the extent and limitations of the data is presented. Example comparisons of the CRwo-media values are given for polonium across all wildlife groups and ecosystems and for molluscs for all radionuclides. The CRwo-media values have also been compared with those currently used in the ERICA Tool which represented the most complete published database for wildlife transfer values prior to this work. The use of CRwo-media values is a pragmatic approach to predicting radionuclide activity concentrations in wildlife and is similar to that used for screening assessments for the human food chain. The CRwo-media values are most suitable for a screening application where there are several conservative assumptions built into the models which will, to varying extents, compensate for the variable data quality and quantity, and associated uncertainty. © 2012, Elsevier Ltd.
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    Protection of the environment
    (SAGE, 2020-08-28) Copplestone, D; Hirth, GA; Cresswell, T; Johansen, MP
    The International Commission on Radiological Protection’s (ICRP) system to protect the living components of the environment is designed to provide a broad and practical framework across different exposure situations. The framework recognises the need to be able to demonstrate an adequate level of protection in relation to planned exposure situations, whilst also providing an ability to manage existing and emergency situations in an appropriate way. In all three exposure situations, the release of radionuclides into the natural environment leads to exposures of non-human biota (wildlife), as well as having the potential for exposures of the public. How the key principles of the ICRP system of radiological protection apply in each of these exposure situations will be discussed. Using examples, we will demonstrate how the overall approach provides a mechanism for industry to assess and demonstrate compliance with the environmental protection objectives of relevant (national) legislation, and to meet stakeholder expectations that radiological protection of the environment is taken into consideration in accordance with international best practice. However, several challenges remain, and these will be discussed in the context of the need for additional guidance on the protection of the environment. Copyright © 2020 by International Commission of Radiological Protection, published by SAGE.
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    Radiological risk assessment to marine biota from exposure to NORM from a decommissioned offshore oil and gas pipeline
    (Elsevier Ltd, 2022-08-11) MacIntosh, A; Koppel, DJ; Johansen, MP; Beresford, NA; Copplestone, D; Penrose, B; Cresswell, T
    Scale residues can accumulate on the interior surfaces of subsea petroleum pipes and may incorporate naturally occurring radioactive materials (NORM). The persistent nature of ‘NORM scale’ may result in a radiological dose to the organisms living on or near intact pipelines. Following a scenario of in-situ decommissioning of a subsea pipelinNe, marine organisms occupying the exteriors or interiors of petroleum structures may have close contact with the scale or other NORM-associated contaminated substances and suffer subsequent radiological effects. This case study used radiological dose modelling software, including the ERICA Tool (v2.0), MicroShield® Pro and mathematical equations, to estimate the likely radiological doses and risks of effects from NORM-contaminated scale to marine biota from a decommissioned offshore oil and gas pipeline. Using activity concentrations of NORM (226Ra, 210Po, 210Pb, 228Ra, 228Th) from a subsea pipeline from Australia, environmental realistic exposure scenarios including radiological exposures from both an intact pipe (external only; accounting for radiation shielding by a cylindrical carbon steel pipe) and a decommissioned pipeline with corrosive breakthrough (resulting in both internal and external radiological exposure) were simulated to estimate doses to model marine organisms. Predicted dose rates for both the external only exposure (ranging from 26 μGy/h to 33 μGy/h) and a corroded pipeline (ranging from 300 μGy/h to 16,000 μGy/h) exceeded screening levels for radiological doses to environmental receptors. The study highlighted the importance of using scale-specific solubility data (i.e., Kd) values for individual NORM radionuclides for ERICA assessments. This study provides an approach for conducting marine organism dose assessments for NORM-contaminated subsea pipelines and highlights scientific gaps required to undertake risk assessments necessary to inform infrastructure decommissioning planning. © 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
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    Recent development of wildlife transfer databases
    (International Union of Radioecology, 2014) Beresford, NA; Copplestone, D; Hosseini, A; Brown, JE; Johansen, MP; Hirth, GA; Sheppard, S; Dagher, E; Yankovich, T; Uchida, S; Napier, J; Outola, I; Wells, C; Barnett, CL; Wood, MD; Howard, BJ
    The transfer of radionuclides to wildlife in the environmental radiological assessment models developed over the last two decades is most often described by the whole organism concentration ratio (CRwo-media). This parameter relates whole organism activity concentrations to those in environmental media (typically soil for terrestrial ecosystems and water for aquatic ecosystems). When first released in 2007, the ERICA Tool contained the most comprehensive and well documented CRwo-media database available for wildlife. It was subsequently used in the US DOE RESRAD-BIOTA model and formed the initial basis for the international wildlife transfer database (WTD; www.wildlifetransferdatabase.org/?) developed to support IAEA and ICRP activities. Subsequently, many additional data were input to the WTD, including the outputs of a review of Russian language literature and data from Canadian monitoring programmes associated with nuclear power plants, U-mining and related industries. Summarised data from the WTD in 2011 were used to provide CRwo values in ICRP 114 and the IAEA's handbook on wildlife transfer parameters (http://www-ns.iaea.org/projects/emras/emras2/working-groups/working-group-five.asp?s=8&l=63). This paper provides an update on the development of the WTD subsequent to 2011 and its application to derive revised default CRwo-media parameter values of the ERICA Tool. Since 2011, some circa 17,000 additional CRwo-media values have been added to the WTD. The new inputs include original data for: representative species of the ICRPs Representative Animals and Plants (RAPs) from a UK forest; monitoring data from Japanese estuaries and Finland; Canadian wildlife; plutonium uptake data from US weapons testing programme sites; wild plants and invertebrates from north western USA; refereed literature published after 2011. Additionally, data already in the WTD from Australia were reviewed with reference to original source reports not previously considered and amended where required. The revised WTD was quality checked by considering the degree of variation in the data for each organism-element combination and the change between the WTD versions. This identified a number of errors (e.g. double entry of data, unit conversion errors and entries based on a dry matter rather than the required fresh weight basis) all of which have now been rectified. Statistical analyses of the WTD have demonstrated that there is currently no justification to subdivide CRwo-media from e.g. mammal to mammal herbivore and mammal carnivore etc.. In revising the ERICA Tool, a more generic categorisation of organisms has subsequently been used. Even with the increase in available data, there are still many radionuclide-organism combinations for which data are lacking. To provide default values where there are no data, a set of rules have been derived including the use of Bayesian statistics. (authors)