Search

Abstract: A new TRS document on Transfer of radionuclides to Wildlife has compiled equilibrium CRwo-media values for a variety of radionuclides and ecosystems. Assessment tools such as the ERICA Tool use equilibrium whole organism concentration ratios (CRwo-media) to predict radionuclide activity concentrations in wildlife from those in media (e.g. water). The aim of this paper is to compare and contrast model predictions of doses from 137Cs to marine organisms using three different approaches: (i) the ERICA Tool utilising the new TRS values to estimate internal and external doses to reference organisms for the Black sea and the Aegean Sea and for the sea close to the Fukushima Dai-ichi plant. (ii) a hydrodynamic site specific model for seawater for parts of the Aegean Sea, Greece which estimates radionuclide concentrations using site specific data and (iii) a biokinetic model for fish applied to the Fukushima releases to the Pacific. The advantages and limitations of these approaches are discussed with respect to determining doses to pelagic fish. The applicability of the three approaches will vary with the objective of an assessment. The site specific model can predict variation in 137Cs with depth and uses site specific CR values. The application of the biokinetic model to predicted 137Cs activity concentrations in seawater and fish due to near coastal inputs from Fukushima Dai-ichi showed that the maximum internal dose-rates in fish attributable to 137Cs would be substantially lower than those determined using equilibrium assumptions in ERICA but the accumulative doses over 100 days were similar. [Copyright &y& Elsevier]

This paper describes, briefly, a deterministic three-dimensional model developed to simulate the trajectory and fate of hypothetical oil spills in coastal waters. The model solves a set of PDE's for two-phase turbulent flow, considering heat and mass transfer among the phases involved and the physical, chemical and biological processes that govern the behavior of oil spills at sea. The model has also incorporated the influence of breaking waves on oil spills, by properly enhancing water turbulence and the natural dispersion of oil in the water column. Model performance is appraised, in the framework of impact assessment studies, by applying it in two particular coastal regions of different topography and bathymetry located in the Aegean Sea, near the island of Lesvos and in the Evoikos bay. [ABSTRACT FROM AUTHOR]

A detailed intercomparison of marine dispersion models applied to the releases from Fukushima Dai-ichi nuclear power plant was carried out in the frame of MODARIA program, of the IAEA. Models were compared in such a way that the reasons of the discrepancies between them can be assessed (i.e., if they are due to the hydrodynamic part, the dispersion part, and the ultimate reasons). A sequential chain of dispersion exercises was carried out with this purpose. The overall idea is to harmonize models, making them run with the same forcing in a step-by-step procedure, in such a way that the main agent in producing discrepancy between models can be found. It was found that the main reason of discrepancies between models is due to the description of the hydrodynamics. However, once this has been suppressed, some variability between model outputs remains due to intrinsic differences between models (as numerical schemes). The numerical experiments were carried out for a perfectly conservative radionuclide and for (137)Cs (including water/sediment interactions). Model outputs for this radionuclide were also compared with measurements in water and sediments., (Copyright © 2015 Elsevier Ltd. All rights reserved.)