The marine <i>kd</i> and water/sediment interaction problem

Periá,ñ,ez, R.,Brovchenko, I.,Jung, K.T.,Kim, K.O.,Maderich, V. Elsevier 2018 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.192 No.-

<P><B>Abstract</B></P> <P>The behavior of marine distribution coefficients is analyzed with the help of numerical experiments and analytical solutions of equations describing kinetic models for uptake/release of radionuclides. The difficulties in measuring true k<SUB>d</SUB> in a marine environment perturbed by an external radionuclide source are highlighted. Differences between suspended matter and bed sediment k<SUB>d</SUB> are analyzed. The performances of different kinetic models (1-step/2step; single-layer/multi-layer) are studied in model/model and model/experiment comparisons. Implications for the use of models to assess radioactive contamination after an emergency are given; as well as recommendations when k<SUB>d</SUB> data are compiled in order to create a useful database.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Equilibrium in radionuclide partition between water and sediment seldom found in the sea. </LI> <LI> Differences between suspended matter and bed sediment kd highlighted. </LI> <LI> One step and two step kinetic models performances compared. </LI> <LI> Single layer and multi-layer models compared. </LI> <LI> Formulation to deal with changes in salinity and pH provided. </LI> </UL> </P>

The behaviour of ¹³⁷Cs in the North Atlantic Ocean assessed from numerical modelling: Releases from nuclear fuel reprocessing factories, redissolution from contaminated sediments and leakage from dumped nuclear wastes

Periá,ñ,ez, R.,Suh, Kyung-Suk,Min, Byung-Il Elsevier 2016 MARINE POLLUTION BULLETIN Vol.113 No.1

<P><B>Abstract</B></P> <P>A Lagrangian model which simulates the dispersion of <SUP>137</SUP>Cs in the North Atlantic has been developed. The model includes water/sediment interactions. It has been tested comparing calculated and measured <SUP>137</SUP>Cs concentrations in water and sediments of the European Shelf resulting after the releases from the nuclear fuel reprocessing plants of Sellafield and La Hague. Some additional numerical experiments have been carried out. First, the redissolution of <SUP>137</SUP>Cs from contaminated sediments after the reduction in releases from the reprocessing plants has been studied. This allowed to calculate effective half-lives of <SUP>137</SUP>Cs in several sub-basins. Later, potential leakage of <SUP>137</SUP>Cs from dumped nuclear wastes in several locations of the Atlantic has been investigated. Even in worst-case scenarios, these leakages should not lead to any radiological implications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Model applied to simulate <SUP>137</SUP>Cs marine dispersion in the North Atlantic </LI> <LI> Calculated Cs concentrations in water and sediments compared with measurements. </LI> <LI> Cs redissolution from contaminated sediments and subsequent transport studied </LI> <LI> Leakage from dumped nuclear waste should not have radiological implications. </LI> </UL> </P>

The behaviour of ²³⁶U in the North Atlantic Ocean assessed from numerical modelling: A new evaluation of the input function into the Arctic

Periá,ñ,ez, R.,Suh, Kyung-Suk,Min, Byung-Il,Villa-Alfageme, M. Elsevier 2018 The Science of the total environment Vol.626 No.-

<P><B>Abstract</B></P> <P>A numerical model, previously validated with other radionuclides, was applied to simulate the dispersion of <SUP>236</SUP>U released from European nuclear fuel reprocessing plants in the North Atlantic and Shelf Seas using a published reconstruction of Sellafield and La Hague releases. Model results are in better agreement with observations if the lowest estimation of such releases are used. This implies that approximately 40kg of <SUP>236</SUP>U has been discharged from Sellafield. It was found that adsorption of <SUP>236</SUP>U on bed sediments of the shallow European Shelf Seas plays an essential role in its dispersion patterns. This contrasts strongly with the more conservative behaviour of <SUP>129</SUP>I in the same area. This has two important implications in the use of <SUP>236</SUP>U as oceanographic tracer; i) special care must be taken in coastal areas, as sediments might act as sinks and sources of <SUP>236</SUP>U; ii) the annual input function of <SUP>236</SUP>U into the Arctic is not directly controlled by the annual discharges from Sellafield and La Hague, since sediments from the Irish, Celtic and North Sea modulate and smooth the signal. Only 52% of the total releases enter into the Arctic Ocean.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Calculated <SUP>236</SUP>U concentrations in water and sediments compared with measurements. </LI> <LI> Adsorption of <SUP>236</SUP>U in bed sediments is significant. </LI> <LI> Releases from Sellafield estimated as 40kg of <SUP>236</SUP>U for period 1952–2013 </LI> <LI> Only 52% of the total releases from the three nuclear facilities are introduced into the Arctic. </LI> <LI> Input function into the Arctic reconstructed: total of 38 ± 8kg of <SUP>236</SUP>U for period 1952–2013. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Should we measure plutonium concentrations in marine sediments near Fukushima?

Periá,ñ,ez, R.,Suh, Kyung-Suk,Min, Byung-Il Springer-Verlag 2013 JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY Vol.298 No.1

Fukushima ¹³⁷Cs releases dispersion modelling over the Pacific Ocean. Comparisons of models with water, sediment and biota data

Periá,ñ,ez, R.,Bezhenar, R.,Brovchenko, I.,Jung, K.T.,Kamidara, Y.,Kim, K.O.,Kobayashi, T.,Liptak, L.,Maderich, V.,Min, B.I.,Suh, K.S. Elsevier Applied Science Publishers 2019 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.198 No.-

<P><B>Abstract</B></P> <P>A number of marine radionuclide dispersion models (both Eulerian and Lagrangian) were applied to simulate <SUP>137</SUP>Cs releases from Fukushima Daiichi nuclear power plant accident in 2011 over the Pacific at oceanic scale. Simulations extended over two years and both direct releases into the ocean and deposition of atmospheric releases on the ocean surface were considered. Dispersion models included an embedded biological uptake model (BUM). Three types of BUMs were used: equilibrium, dynamic and allometric. Model results were compared with <SUP>137</SUP>Cs measurements in water (surface, intermediate and deep layers), sediment and biota (zooplankton, non-piscivorous and piscivorous fish). A reasonable agreement in model/model and model/data comparisons was obtained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Marine dispersion models applied to Fukushima releases in the Pacific Ocean. </LI> <LI> Biological uptake model included within physical dispersion models. </LI> <LI> Model results compared with measurements in water, sediments and biota. </LI> <LI> Generally good agreement in model/model and model/data comparisons. </LI> </UL> </P>

Modelling of marine radionuclide dispersion in IAEA MODARIA program: Lessons learnt from the Baltic Sea and Fukushima scenarios

Periá,ñ,ez, R.,Bezhenar, R.,Brovchenko, I.,Duffa, C.,Iosjpe, M.,Jung, K.T.,Kobayashi, T.,Lamego, F.,Maderich, V.,Min, B.I.,Nies, H.,Osvath, I.,Outola, I.,Psaltaki, M.,Suh, K.S.,de With, G. Elsevier 2016 Science of the Total Environment Vol.569 No.-

<P><B>Abstract</B></P> <P>State-of-the art dispersion models were applied to simulate <SUP>137</SUP>Cs dispersion from Chernobyl nuclear power plant disaster fallout in the Baltic Sea and from Fukushima Daiichi nuclear plant releases in the Pacific Ocean after the 2011 tsunami. Models were of different nature, from box to full three-dimensional models, and included water/sediment interactions. Agreement between models was very good in the Baltic. In the case of Fukushima, results from models could be considered to be in acceptable agreement only after a model harmonization process consisting of using exactly the same forcing (water circulation and parameters) in all models. It was found that the dynamics of the considered system (magnitude and variability of currents) was essential in obtaining a good agreement between models. The difficulties in developing operative models for decision-making support in these dynamic environments were highlighted. Three stages which should be considered after an emergency, each of them requiring specific modelling approaches, have been defined. They are the emergency, the post-emergency and the long-term phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Models applied to simulate <SUP>137</SUP>Cs marine dispersion after nuclear accidents. </LI> <LI> Not good agreement initially found in highly dynamic environments. </LI> <LI> Difficulties in developing models for decision making after emergencies highlighted. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>