M. Iosjpe - Academia.edu (original) (raw)

Papers by M. Iosjpe

Science of The Total Environment, 1997

A box model for the dispersion of radionuclides in the marine environment covering the Arctic Oce... more A box model for the dispersion of radionuclides in the marine environment covering the Arctic Ocean and the North Atlantic Ocean has been constructed. Collective doses from ingestion pathways have been calculated from unit releases of the radionuclides 3H, 6oCo, 63Ni, 90Sr, lz91, 137Cs, 239Pu and 241Am into a fjord on the east coast of NovayaZemlya. The results show that doses for the shorter-lived radionuclides (e.g. 137Cs) are derived mainly from seafood production in the Barents Sea. Doses from the longer-lived radionuclides (e.g. 239Pu) are delivered through marine produce further away from the Arctic Ocean. Collective doses were calculated for two release scenarios, both of which are based on information of the dumping of radioactive waste in the Barents and Kara Seas by the former Soviet Union and on preliminary information from the International Arctic Sea Assessment Programme. A worst-case scenario was assumed according to which all radionuclides in liquid and solid radioactive waste were available for dispersion in the marine environment at the time of dumping. Release of radionuclides from spent nuclear fuel was assumed to take place by direct corrosion of the fuel ignoring the barriers that prevent direct contact between the fuel and the seawater. The second scenario selected assumed that releases of radionuclides from spent nuclear fuel do not occur until after failure of the protective barriers. All other liquid and solid radioactive waste was assumed to be available for dispersion at the time of discharge in both scenarios. The estimated collective dose for the worst-case scenario was about 9 ma&v and that for the second scenario was about 3 manSv. In both cases 13'Cs is the radionuclide predicted to dominate the collective doses as well as the peak collective dose rates. 0 1967 Elsevier Science B.V.

Radioprotection, 2005

Two models with different conceptual and numerical approaches have been used to simulate the disp... more 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.

Marine Pollution Bulletin, 2002

Measurements of samples taken from the close vicinity of the Kursk during two expeditions to the ... more Measurements of samples taken from the close vicinity of the Kursk during two expeditions to the site in August and October 2000, indicate that no leakage of radionuclides from the reactors has been observed. Only background levels in the range 0:0-0:1 lSv=h have been measured by use of the remote operating vehicle (ROV) or by the divers working on and inside the submarine. Preliminary model calculations based on two different scenarios, representing short-and long-term releases of 100% of the reactors radionuclide inventory, show that the impact on man and the environment from the Kursk should not be deemed very serious. The conservative estimates indicate a maximum 137 Cs activity concentration in fish in the order of about 80-100 Bq/kg and a total collective dose of 97 manSv. Ó

Journal of Environmental Radioactivity, 2002

One of the general assumptions for box modelling of the dispersion of radionuclides in marine sys... more One of the general assumptions for box modelling of the dispersion of radionuclides in marine systems relates to instantaneous mixing in each box which, in turn, results in practical calculations involving instantaneous mixing in the whole of oceanic space. A new approach to box modelling, which includes dispersion of radionuclides as a function of time, was therefore developed in order to provide a better and more realistic/physical approximation to reality relative to traditional box modelling. The novel and significant practical features of the approach are discussed. Calculations of concentrations of radionuclides in the marine environment and doses to man for some scenarios indicate differences of up to orders of magnitude between the traditional and new approaches to box modelling.

Journal of Environmental Radioactivity, 2004

The radionuclide 99 Tc had been discharged from the nuclear reprocessing facility in Sellafield (... more The radionuclide 99 Tc had been discharged from the nuclear reprocessing facility in Sellafield (UK) into the Irish Sea in increased amounts in the 1990s. We compare the simulated dispersion of 99 Tc in surface water as calculated by a hydrodynamic model and an assessment box model with field-observations from 1996 to 1999 to study concentrations, pathways and travel times. The model results are consistent with the observations and show the typical pathway of dissolved radionuclides from the Irish Sea via the North Sea along the Norwegian Coast. Subsequently the contaminated water separates into three branches of which the two Arctic branches bear the potential for future monitoring of the signal in the next decades. The results of the hydrodynamic model indicate a large variability of surface concentrations in the West Spitsbergen Current which has implications for future monitoring strategies. According to the observed and simulated distributions we suggest an improved box model structure to better capture the pattern for concentrations at the surface. #

Journal of Environmental Radioactivity, 2009

This article presents results pertaining to a risk assessment of the potential consequences of a ... more This article presents results pertaining to a risk assessment of the potential consequences of a hypothetical accident occurring during the transportation by ship of spent nuclear fuel (SNF) along an Arctic coastline. The findings are based on modelling of potential releases of radionuclides, radionuclide transport and uptake in the marine environment. Modelling work has been done using a revised box model developed at the Norwegian Radiation Protection Authority. Evaluation of the radioecological consequences of a potential accident in the southern part of the Norwegian Current has been made on the basis of calculated collective dose to man, individual doses for the critical group, concentrations of radionuclides in seafood and doses to marine organisms. The results of the calculations indicate a large variability in the investigated parameters above mentioned. On the basis of the calculated parameters the maximum total activity (''accepted accident activity'') in the ship, when the parameters that describe the consequences after the examined potential accident are still in agreement with the recommendations and criterions for protection of the human population and the environment, has been evaluated.

Journal of Environmental Radioactivity, 2012

The knowledge about environmental sensitivity of the marine regions to radionuclide release can b... more The knowledge about environmental sensitivity of the marine regions to radionuclide release can be used for the development of response strategies and improvement of design-maker systems. The present results are based on the consequences analysis after potential Russian submarine accident involving a modern vessel. The radioecological consequences are based on modelling of potential releases of radionuclides, radionuclide transport and uptake in the marine environment. The sensitivity analysis is based on the comparison of the results of simulations with the recommendations and criterions for protection of the human population and the environment. The results show that the doses to marine organisms living in the sea sediment near the accident location, and dose rates to the critical group are the most sensitive state parameters (endpoints) for describing the consequences to the marine environment in the present evaluation.

Journal of Environmental Radioactivity, 2013

This paper describes modelling calculations carried out to determine the sensitivity of various r... more This paper describes modelling calculations carried out to determine the sensitivity of various rural and semi-natural environments to radionuclide contamination by 137 Cs, 90 Sr, and 131 I released during a major nuclear accident. Depositions of 1000 Bq/m 3 were assumed for each radionuclide. Four broad types of environments were considered: agricultural, forest or tundra, freshwater aquatic, and coastal marine. A number of different models were applied to each environment. The annual dose to a human population receiving most or all of its food and drinking water from a given environment was taken as a broad measure of sensitivity. The results demonstrated that environmental sensitivity was highly radionuclide specific, with 137 Cs generally giving the highest doses during the first year, especially for adults, in terrestrial and freshwater pathways. However, in coastal marine environments, 131 I and 239 Pu were more significant. Sensitivity was time dependent with doses for the first year dominating those for the 2nd and 10th years after deposition. In agricultural environments the ingestion dose from 137 Cs was higher for adults than other age groups, whereas for 90 Sr and 131 I, the ingestion dose was highest for infants. The dependence of sensitivity on social and economic factors such as individual living habits, food consumption preferences, and agricultural practices is discussed.

Journal of Environmental Radioactivity, 2015

Dispersion Sediment Box models Hydrodynamic models a b s t r a c t Four radionuclide dispersion m... more Dispersion Sediment Box models Hydrodynamic models a b s t r a c t Four radionuclide dispersion models have been applied to simulate the transport and distribution of 137 Cs fallout from Chernobyl accident in the Baltic Sea. Models correspond to two categories: box models and hydrodynamic models which solve water circulation and then an advection/diffusion equation. In all cases, interactions of dissolved radionuclides with suspended matter and bed sediments are included. Model results have been compared with extensive field data obtained from HELCOM database. Inventories in the water column and seabed, as well as 137 Cs concentrations along 5 years in water and sediments of several sub-basins of the Baltic, have been used for model comparisons. Values predicted by the models for the target magnitudes are very similar and close to experimental values. Results suggest that some processes are not very relevant for radionuclide transport within the Baltic Sea, for instance the roles of the ice cover and, surprisingly, water stratification. Also, results confirm previous findings concerning multi-model applications.