Observations carried out in the frame of the ISTC project 3547 [1] were used to parametrize and validate the model of radionuclides transport from Siberian Chemical Combine (SCC) by the Tom and Ob rivers and also to assess discharges of radioactive substances from SCC to the Tom River and to estimate possible contamination of the rivers in case of accidents.

The two-chamber (water and bottom sediments) model was used to analyze factors influencing magnitude of 137 Cs accumulation factor in bottom sediments of rivers and lakes with concentration of the radionuclide close to background levels. The most probable values of the factor are given. It is proposed to use the factor for assessments of 137 Cs activity in water on the base of its observed activity in bottom sediments.

In case of an accident at a radioactively dangerous object it is necessary to assess promptly possible consequences. Such prompt assessments are almost impossible without appropriate software modelling tools. Nuclear Safety Institute of Russian Academy of Sciences has developed the set of computer programs that enables experts to assess promptly impact of possible accidents on population and environment. The set of software tools includes: models of radionuclides transport in the atmosphere and water objects (rivers, lakes and ponds). It also includes models of assessment of doses of radioactive exposure of humans. The adequate modelling is not possible without accurate electronic maps of the neighborhood of a Nuclear Power Plant (NPP). Thus the electronic maps of neighborhood of all Russian NPP's are supplemented to the set of tools. The necessary data on local population and water objects surrounding NPP's is also included and stored in GIS-based (Geographical Information System) database. That enables numerical modelling to be done within tens of minutes at most. The GIS enables use of spatial data on fallout of radioactive substances from the model of atmospheric transport to be used as input data for modelling of transport in water objects.

Relatively simple compartmental models of transport of radioactive substances by a uniform flow are quite often successfully used for assessment of concentrations of radionuclides in water, bottom sediments and flood plains of rivers. However, one should take into account specificity of contamination of a river to be simulated. In this work the results of modelling of Sr-89,Sr-90, (CS)-C-137, and (PU)-P-239,240 migration in the Techa River were compared with observed data. As a result of the comparison the authors have supposed that taking into account of the process of mass exchange between the main stream of a river and underflow is important for the adequate modelling of migration and accumulation of radionuclides (and other contaminants with similar physical and chemical properties) in rivers that were polluted during a long period of time. It is known that underflow of a river can reach 30% of the main stream. The performed analysis of comparison of the modelling results with the observed data has enabled an evaluation of numerical values of parameters by means of which the interaction between the main stream and the underflow may be described. The choice of the Techa-river as an example was not casual. For more than 50 years the "Mayak" plant was fulfilling its important defense mission and discharged contaminated effluents to the Techa-river. As a result the whole river and its basin have become contaminated by long-lived radionuclides. The issues of the Techa-river contamination by radionuclides and simulation of their transport have been given attention over decades by many scientists.

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In this contribution, we demonstrate that a material (organic zeolite mimetic coordination polymer [CuL(2)], where L = L(-) = CF(3)COCHCOC(OCH(3))(CH(3))(2)) can be endowed with its functionality in situ under molecular-level control. This process involves the isomerization of the ligands followed by phase interconversion from a dense to an open, porous form. The porous (beta) form of the complex reveals zeolite-like behavior but, unlike zeolites and many other hard porous frameworks, porosity may be created or destroyed at will by the application of suitable external stimuli. Contact with methylene chloride vapor was used to switch on the sorbent functionality, whereas switching off was accomplished with a temperature pulse. The transformations between functionally inactive alpha and active beta forms, as well as the amount of vacant pore space, were monitored in situ by observing the NMR spectrum of hyperpolarized (HP) Xe atom probes. For methylene chloride, the chemical shift of the coabsorbed HP Xe correlated directly with the amount of adsorbate in the pore system of the open framework, illustrating the use of HP Xe for following sorption kinetics. The adsorption of propane, as an inert adsorbate, was also monitored directly with (1)H NMR, with HP Xe and by BET measurements, revealing more complex behavior.