Modified approach to modelling radiological consequences from releases into the marine environment

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Abstract. The evaluation of environmental vulnerability is one of the key factors in need of consideration during the improvement of decision-making systems and the development of response strategies to radionuclide release into marine regions. Environmental marine modelling has to simultaneously describe the dispersion of radionuclides in water and sediment phases; bioaccumulation of radionuclides in biota and finally, dose assessments. It is obvious that such an approach comes up against the problem of complexity and the need for a large set of parameters. The sensitivity analysis of the model parameters can contribute to a better understanding of experimental data as well as define parameters which can play a key role in the evaluation of environmental vulnerability. In the present paper sensitivity analysis has been carried out using the compartment modelling approach for assessment of the environmental vulnerability as dose to man. The sensitivity analysis shows that the influence of model parameters can vary greatly depending on the concrete radionuclude and on the marine region. It is also shown that the results of the sensitivity parameter analysis can contribute to the process of defining which parameters can play an important role in the dose assessment and the evaluation of environmental vulnerability.

Section: Methodsmentioning

confidence: 99%

Evaluation of the environmental parameters controlling the vulnerability of the coastal marine regions

Iøsjpe

2011

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“…The classic box modelling approach described in (2) was modified by Iosjpe et al (1) to avoid the assumption of instantaneous mixing of radionuclides into each model box, that leads, in practical calculations, to instantaneous mixing in the whole oceanic space. This feature of traditional box modelling is not liable to describe correctly the water motion of large oceanic systems.…”

Section: Long-term Box Model For the North Atlantic And Arctic Oceansmentioning

confidence: 99%

“…These are defined as the first time when a given box is opened to accept radionuclides from the others. The mathematical description of the availability times can be seen in detail in Iosjpe et al (1).…”

Section: Long-term Box Model For the North Atlantic And Arctic Oceansmentioning

confidence: 99%

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Redissolution of caesium and plutonium from Irish Sea sediments: A comparison between different modelling approaches

Iøsjpe¹,

Periáñez

2005

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Abstract. Two models with different conceptual and numerical approaches have been used to simulate the dispersion of radionuclides released from Sellafield nuclear fuel reprocessing plant. The first is a long-term box-model for simulating dispersion from Sellafield to the Arctic environment in which water fluxes between boxes are obtained from basic oceanographic information. Water-sediment radionuclide exchanges are described through sedimentation and remobilisation processes on the basis of equilibrium distribution coefficients. The second model is a 3D high-resolution model that explicitly solves tidal mixing and suspended sediment transport in the Irish Sea. Exchanges of radionuclides between the liquid and solid phases are now described in terms of kinetic rates. Thus, this model has a general applicability and can be used in situations out from equilibrium. Both models have been used to simulate the dispersion of Cs and Pu in the Irish Sea. Results from the two models are comparable, being differences in the results smaller than should be expected from the very different modelling approaches.

“…[1]), the contaminant concentration is calculated in each compartment. The exchanges between the compartments are defined by transfer coefficients that represent the fluxes of water, salinity and suspended particulate matter (SPM).…”

Section: Introductionmentioning

confidence: 99%

Modelling the long term dispersion of radioactive liquid effluent and dose from marine pathways using a grid model

Gleizon¹,

McDonald²,

Bryan³

2009

Abstract. A grid model was developed to combine small-scale grid resolution and long-term predictions of radionuclide dispersion in shallow seas. A predictor-corrector algorithm ensures an unconditional stability of the model. Four modules calculate the concentration of suspended sediments, the dispersion of radionuclides in the marine environment, and the doses to members of the public and marine biota. The model was applied to the dispersion of liquid effluent in the Irish Sea from the Sellafield nuclear reprocessing plant, Cumbria (UK). The concentration factors and partition coefficients have been calibrated for biota species and local conditions. The validation against environmental samples for twenty-two radionuclides shows a good agreement between predicted and measured values.