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This book is a practical guide to the subject of numerical modelling of radioactivity dispersion in the marine environment. Thus, the techniques and numerical procedures required are explained in detail, with the aim of enabling the reader to build a real mathematical model. The book covers basic concepts and techniques, such as solving the advection-diffusion equation in a simple 1D form, as well as the most recent developments (full 3D models for non-conservative radionuclides including chemical reactions and speciation). A chapter is dedicated to the basic hydrodynamic modelling that is always required to simulate the dispersion of tracers in the sea; Eulerian and Lagrangian modelling techniques are also described. A chapter describes sensitivity and uncertainty analysis, the final stage in modelling works. A review on some published radionuclide dispersion models is also included. The book also includes a CD-ROM with a Lagrangian dispersion model of the Strait of Gibraltar and several Fortran codes developed by the author which can be used to reproduce some of the cases described in the book.
This publication describes and summarizes the work of the MODARIA (modelling and data for radiological impact assessments) Programme Working Group 10. MODARIA was set up to continue the IAEA's activities in the field of testing, comparing and developing guidance on the application of models to assess radiation exposures to humans and radiological impacts on the environment. Different aspects of the MODARIA programme were addressed by ten working groups. The current publication presents the work undertaken by Working Group 10 on the modelling of marine dispersion and transfer of radionuclides accidentally released from land-based facilities. Two marine dispersion scenarios were studied. These scenarios simulated dispersion of radionuclides in the Baltic Sea following the Chernobyl accident, and dispersion in the Pacific Ocean following the Fukushima Daiichi nuclear power plant accident. The publication details some general conclusions and presents a comparison of model performance when applied to the above scenarios. The difficulties of developing operative modelling systems for supporting decision making in cases of emergencies in highly dynamic environments are highlighted.
The Norwich Symposium, 'Radionuclides in the Study of Marine Proces ses', is a sequel to the very successful conference held at Cherbourg, France in June 1987. The international character of the meeting has been maintained with thirty-eight contributions, from seventeen countries, being accepted for oral presentation. For many years, the radioactive properties of the naturally occurring radionuclides have been used to determine their distributions in the marine environment and, more generally, to gain an understanding of the dynamic processes which control their behaviour in attaining these distributions. More recently the inputs from human activities of both natural and artificial (i.e. man-made) radionuclides have provided additional opportunities for the study of marine processes on local, regional and global scales. Because the sources of artificial radionuclides are often reasonably well defined in space and time, and because a wider range of elements is represented, new viewpoints for the study of processes have become available. Although it is outside the scope of this Symposium, it must be acknowledged that the radiological protection requirements for radioactive waste disposal prac tices to be based on a sound scientific understanding of radionuclide behaviour in the sea have also provided a very strong impetus for the studies.
A 3D mathematical model LMT3D has been developed and adapted to simulate the transport and dispersion of radioactive (RA) pollutants around dumping sites. The model consists of two coupled sub-models:hydrodynmic sub-model and mass-transport submodel. The hydrodynamic sub-model is 3D, non-linear and baroclinic. A finite hybrid numerical scheme is used in a orthogonal grid to solve the basic equations. The mass-transport sub-model solves the advection-diffusion equation by a lagrangian-based particle tracking method. Several forcing factors can be occounted for in both sub-models: wind forcing,thermo-haline forcing, inflow of rivers or inflow/outflow through straits. The integrated model was applied to carry out a detailed study of transport-dispersion of RA pollutants in the Japan Sea. The report presents a description of the problem, the model and the results. A large amount of radioactive (RA) waste has been deposited in the Japan Sea at the sea bottom, at a depth of about 3500 meters. Although several measurements of RA pollution in this sea have shown no increase of radioactivity over the natural values, concern exists that there may be some leakage of the RA pollutants from the dumped waste. The question is where they might be transported by currents and dispersion, and especially after what time and where they would reach the surface layers, where they might contaminate fish and other marine organisms.
Although several countries dispose of their radioactive waste in the world's oceans, recent revelations by the former Soviet Union concerning disposal of radioactive waste in the shallow water of the Kara Sea have created widespread environmental concern. The Yablokov Report or the White Book is the official Russian documentation of source locations, the time of dumping and the amounts and types of radioactive materials that have been dumped. The report states that low level liquid waste was dumped into the Kara and Barents Seas with lesser amounts dumped into the White Sea and the Baltic. Low to intermediate waste was dumped into the Kara and Barents Seas. The material assumed the most environmentally hazardous was solid radioactive waste with spent nuclear fuel. Nuclear reactors containing the spent nuclear fuel were deposited along the eastern coast of Novaya Zemlya island in water with average depths between 20-40 m. Major river/estuary systems located in the Kara and Barents Seas, particularly the larger Ob and Yenisei rivers as well as the smaller Pechora river, are additional sources. The disposal of liquid radioactive waste at the Sellafield site in the Irish Sea has also been suggested as a source of radioactivity for the Barents and the Kara Sea.