Research of the Uranium,Niobium, and Tantalum Behavior in the Granite Melt–Chloride Fluid System at 750°C and 1000 Bar

Geology of Ore Deposits - The major objective of the study investigation was to find the physicochemical conditions for U, Nb, and Ta mobilization into the solution from acidic melts similar in...     

Estimation of the time of magma chamber solidification beneath the Strel’tsovka caldera and its effect on the nonstationary temperature distribution in the upper crust,the eastern Transbaikal region,Russia

The hydrothermal Mo-U deposits of the Strel’tsovka ore field, unique in reserves, are localized in the Late Mesozoic caldera of the same name. The consideration of geochemical processes that controlled uranium transfer by ore-bearing fluids and its precipitation in orebodies has shown that a nonstationary temperature distribution could have exerted a substantial effect on ore formation. The temperature field in the Strel’tsovka caldera, which was caused by a shallow-seated magma chamber that existed beneath the caldera by the onset of the ore stage, was simulated by mathematical modeling. A one-dimensional nonstationary model of conductive heat transfer taking into account the latent heat of magmatic melt crystallization was used. The problem was solved with the finite difference method. It has been established that, at optimal parameters of the model, the magma chamber would have completely crystallized in 56 ka; the maximum estimate is 133 ka. Three million years after emplacement of the granitic intrusion, the related thermal anomaly in the upper crust should have disappeared. The results obtained indicate that granitic melt of this chamber could not have been a source of uranium-bearing solutions that formed deposits 5 Ma after the cessation of magmatic activity.     

Geographical characteristics of migration linkages in the Moscow capital region

"A study of migration processes in the Moscow Capital Region over the period 1970-1985 begins by assessing their contribution to overall population growth within the region vis-a-vis natural increase and territorial and administrative changes. Attention then is turned toward movements both within the Moscow Capital Region and between it and other oblasts of the European RSFSR. Although the overall volume of migration within the Moscow capital Region and between it and remaining oblasts of the European RSFSR declined, the relative popularity of the former as a destination among migrants in European Russia remained unchanged."     

Geological conditions of safe long-term storage and disposal of depleted uranium hexafluoride

The production of enriched uranium used in nuclear weapons and fuel for atomic power plants is accompanied by the formation of depleted uranium (DU), the amount of which annually increases by 35–40 kt. To date, more than 1.6 Mt DU has accumulated in the world. The main DU mass is stored as environ-mentally hazardous uranium hexafluoride (UF₆), which is highly volatile and soluble in water with the formation of hydrofluoric acid. To ensure safe UF₆ storage, it is necessary to convert this compound in chemically stable phases. The industrial reprocessing of UF₆ into U₃O₈ and HF implemented in France is highly expensive. We substantiate the expediency of long-term storage of depleted uranium hexafluoride in underground repositories localized in limestone. On the basis of geochemical data and thermodynamic calculations, we show that interaction in the steel container-UF₆-limestone-groundwater system gives rise to the development of a slightly alkaline reductive medium favorable for chemical reaction with formation of uraninite (UO₂) and fluorite (CaF₂). The proposed engineering solution not only ensures safe DU storage but also makes it possible to produce uraninite, which can be utilized, if necessary, in fast-neutron reactors. In the course of further investigations aimed at safe maintenance of DU, it is necessary to study the kinetics of conversion of UF₆ into stable phases, involving laboratory and field experiments.     

F. I. Wolfson: Scientist,teacher, and patriot

Following a brief biography, the scientific, administrative, and educational activity of F.I. Wolfson is described. Also considered are the principal lines of his research: the study of the structures of ore fields and deposits, the geology of uranium deposits, the theory of hydrothermal ore formation, and the history of the study of ore deposits. The immense contribution made by Wolfson to the development of the mineral resources of the country (uranium, nonferrous metals, etc.) is shown and the continuing relevance of his theoretical and methodological works in the field of geology of ore deposits is emphasized.