Application of Physical Methods for Reducing Plutonium Hexafluoride

The exploding-wire method, the photochemical method of irradiation with a light flux from a high-pressure mercury lamp, a high-intensity spark discharge, and irradiation by a CO₂ laser are used to reduce plutonium hexafluoride and to separate it from uranium hexafluoride. The dependence of the reduction of plutonium hexafluoride on the wire material, the mass of the reduced product, and the amount of input energy is investigated.It is shown that the methods presented for reducing plutonium hexafluoride and separating it from uranium hexafluoride can be used under static and dynamic conditions for preparative purposes and on a large scale.     

Current municipal solid waste management in the cities of Astana and Almaty of Kazakhstan and evaluation of alternative management scenarios

Clean Technologies and Environmental Policy - The present paper provides a detailed analysis of the current situation on municipal solid waste (MSW) management in Kazakhstan with focus on the two...     

Results of long-term operation of cascade tubular air heaters at the Berezovskaya GRÉS

Experience of operation of tubular air heaters (TAH) on twelve boilers of type PK-38 for 150-MW power units of the Berezovskaya GRÉS (state regional power plant) in Belarus is presented. Coal-fired, gas-fired, and oil-fired operation modes with updating tubular air heaters in a cascade layout are described. Advantages of the cascade layout and conditions for reliable, efficient, and long-term service of the TAH are shown.Translated from Élektricheskie Stantsii, No. 9, September 2004, pp. 20–23.     

Low-Temperature Synthesis of Plutonium Hexafluoride

Fluoridation of uranium tetrafluoride by atomic fluorine and radiolytic plutonium tetrafluoride by atomic fluorine and dioxygen difluoride are investigated. The mechanism and the limiting stages of the processes with atomic fluorine are described. It is shown that plutonium tetrafluoride is fluoridated directly by dioxygen difluoride molecules and not by the products of its thermal decomposition.Kinetic equations are obtained for the fluoridation of plutonium tetrafluoride. These equations are of first order in the gaseous reagent and the specific surface area of tetrafluoride. The effectiveness of atomic fluorine and dioxygen difluoride for synthesis and recovery of plutonium hexafluoride are compared.     

Subsidence control method by inversely-inclined slicing and upward mining for ultra-thick steep seams

Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation. A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper. By this method, the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed, the extent of roof-side deformation thereby is lessened, and boundary angle of roof-side subsidence is reduced by 5°–10°. The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials. A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method. The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.     

Regularities in the Sorption of Plutonium Hexafluoride

When implemented, the modern methods for reprocessing nuclear fuel which are based on the volatility of fluorides are complicated by the physical adsorption of uranium and plutonium hexafluorides on inorganic compounds. The lack of the required experimental data in this field makes it impossible to describe the kinetics of the behavior of the indicated hexafluorides in the various processes involved in obtaining and reprocessing them. Consequently, the study of the adsorption of uranium and plutonium hexafluorides and the determination of the heat and entropy of adsorption are of interest from the scientific standpoint and for applications. This paper is devoted to the study of these questions.__________Translated from Atomnaya Energiya, Vol. 98, No. 5, pp. 341–348, May 2005.     

Using microorganisms to process liquid radioactive wastes

Kurchatov Institute, Russian Scientific Center. Microbiology Institute, Russian Academy of Sciences. Translated from Atomnaya Énergiya, Vol. 74, No. 2, pp. 123-127, February, 1993.     

Reduction of Plutonium Hexafluoride Using Gaseous Reagents

The direct reduction of plutonium hexafluoride to dioxide in an oxygen–methane flame with various ratios of the initial components is investigated. The basic factors which influence the residual fluorine content in plutonium dioxide and the bulk density of the latter are determined. Plutonium dioxide samples with fluorine content not exceeding 5·10^–3 mass% are obtained. A mechanism is proposed for the reduction process.It is shown that carbon monoxide is useful as a reducing agent for obtaining dioxides of actinide elements by direct reduction of the corresponding hexafluorides.