Browsing by Author "Orr, B"

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    Atmospheric transport modelling of time resolved 133Xe emissions from the isotope production facility ANSTO, Australia
    (Elsevier, 2013-12) Schöppner, M; Plastino, W; Hermanspahn, N; Hoffmann, EL; Kalinowski, M; Orr, B; Tinker, R
    The verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT) relies amongst other things on the continuous and worldwide monitoring of radioxenon. The characterization of the existing and legitimate background, which is produced mainly by nuclear power plants and isotope production facilities, is of high interest to improve the capabilities of the monitoring network. However, the emissions from legitimate sources can usually only be estimated. For this paper historic source terms of 133Xe emissions from the isotope production facility at ANSTO, Sydney, Australia, have been made available in a daily resolution. Based on these high resolution data, different source term sets with weekly, monthly and yearly time resolution have been compiled. These different sets are then applied together with atmospheric transport modelling (ATM) to predict the concentration time series at two radioxenon monitoring stations. The results are compared with each other in order to examine the improvement of the prediction capability depending on the used time resolution of the most dominant source term in the region. © 2013 Elsevier Ltd. Published by Elsevier Ltd. All rights reserved.
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    Evaluation of radioxenon releases in Australia using atmospheric dispersion modelling tools.
    (Elsevier, 2010-05) Tinker, R; Orr, B; Grzechnik, M; Hoffmann, EL; Saey, P; Solomon, S
    The origin of a series of atmospheric radioxenon events detected at the Comprehensive Test Ban Treaty Organisation (CTBTO) International Monitoring System site in Melbourne, Australia, between November 2008 and February 2009 was investigated. Backward tracking analyses indicated that the events were consistent with releases associated with hot commission testing of the Australian Nuclear Science Technology Organisation (ANSTO) radiopharmaceutical production facility in Sydney, Australia. Forward dispersion analyses were used to estimate release magnitudes and transport times. The estimated 133Xe release magnitude of the largest event (between 0.2 and 34 TBq over a 2 d window), was in close agreement with the stack emission releases estimated by the facility for this time period (between 0.5 and 2 TBq). Modelling of irradiation conditions and theoretical radioxenon emission rates were undertaken and provided further evidence that the Melbourne detections originated from this radiopharmaceutical production facility. These findings do not have public health implications. This is the first comprehensive study of atmospheric radioxenon measurements and releases in Australia. © 2010, Elsevier Ltd.
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    Global seafood dose 2023: assessment by an international team
    (ICRP, 2023-11-06) Johansen, MP; Carpenter, JG; Charmasson, S; Gwynn, JP; McGinnity, P; Mori, A; Orr, B; Simon-Cornu, M; Osvath, I
    It has been known for many years that ingestion dose from seafood is an important component of the background dose rates for billions of consumers worldwide and that eating seafood can contribute proportionally higher dose as compared with terrestrial-sourced foods. However, a well-supported and current estimate of the contribution of seafood to the dose of global consumers is not available. This is mainly because of the difficulty in assembling the underlying data on a global scale, but also due to the varied and dynamic nature of exposures. Global seafood consumption is increasing, diet patterns are shifting (e.g., toward more farmed products), and new inputs of radionuclides into marine systems have occurred (e.g., the Fukushima accident). A new assessment is being conducted on seafood dose in the context of the ongoing stresses on ocean resources and protection of the marine environment. Its global scale makes use of a much-expanded database on radionuclides in seafood (Marine Radioactivity Information System -MARIS) as well as global diet data and updated parameters for dose calculation. The new assessment: • Evaluates global data on 16 natural and anthropogenic radionuclides. • Draws from more than 84,856 activity concentrations data for biota. • Uses seafood consumption data representing approximately 35% of the world population drawn from national and sub-national diet studies. • Develops new correction factors for the loss of 210Po during cooking, radiological decay during storage, as well as the decreases in 210Po in maricultured seafood. • Implements a bespoke Monte Carlo application for calculating seafood dose distributions. • Compiles and evaluates 150+ seafood ingestion dose estimates published in the past 30 years. The new results indicate somewhat higher seafood dose rates for typical global consumers than previous comprehensive assessments (UNSCEAR, MARDOS). Compared with the 150+ previous individual published studies, our distribution of global dose matches closely and helps explain and interpret the previous estimates. Most background seafood dose is from naturally-sourced 210Po (~80%) followed by 210Pb (+10%) and the Ra radionuclides (~7%). A comparatively small background dose (<0.01%) comes from the ambient anthropogenic radionuclides in seafood that derive from worldwide fallout, accidents, releases from waste sites and similar sources. Study outcomes are useful in providing benchmark references for dose assessments performed on the local, regional and national scale for planned facilities or for evaluating accidental releases. They also provide a baseline for quantifying the changes in seafood dose over time. Results show that typical seafood doses are changing as they reflect trends toward more maricultured products (which can have markedly lower levels of 210Po), various stresses and impacts on world fisheries as well as the evolution of seafood production and distribution systems. Numerous researchers and organisations worldwide have provided input into the project. The assessment is being conducted within the IAEA Coordinated Research Project “Behaviour and Effects of Natural and Anthropogenic Radionuclides in the Marine Environment and their Use as Tracers for Oceanography Studies.”