Development and trials of a technology for reprocessing of NPP liquid radioactive wastes

Laboratory trials of a process for sorption decontamination of real NPP bottom residues from Cs radionuclides with Termoksid-35 ferrocyanide sorbent and rig and pilot trials of the technology for reprocessing of bottom residues from a number of Russian nuclear power plants were performed. The efficiency of the Cs sorption drastically decreases in the presence of organic complexing agents (EDTA, oxalate ions). Preliminary ozonation of the bottom residue allows the working life of Termoksid-35 sorbent in the decontamination process to be increased by a factor of several tens. Rig and pilot trials showed that ozonation of bottom residues, followed by microfiltration separation of the precipitate formed, ensures efficient decontamination of the solutions from Co, Mn, and Sr radionuclides and from α-emitters. A technology was suggested for decontamination of NPP bottom residues from radionuclides, involving ozonation, microfiltration, and selective sorption of Cs radionuclides on Termoksid-35 ferrocyanide sorbent. Process and technical solutions obtained in the course of trials were implemented in an industrial installation for reprocessing of bottom residues from the Kola NPP.     

Development of a process for treatment and solidification of liquid radioactive concentrates from the Leipunskii Institute of Energy Physics

Treatment of liquid radioactive concentrates (LRCs) from the Leipunskii Institute of Energy Physics using Termoksid-35 ferrocyanide sorbent was studied. After passing LRC with a volume activity of 3.9 × 10⁸ Bq l⁻¹ through a column packed with the sorbent, the volume activity of the filtrate does not exceed 3.7 × 10⁴ Bq l⁻¹. The LRC decontaminated from the major amount of radionuclides is fed to cementation. A formulation of a cement compound with a polyfunctional additive consisting of finely dispersed cement, bentonite clay, biocidal additive, plasticizer, and defoamer was developed. For the storage of a container filter with the spent ferrocyanide sorbent, it is suggested to place it in a 1 m³ metallic container in which the cement compound with the LRC decontaminated from the major fraction of cesium acts as biological protection. The γ-radiation dose rate from the 1 m³ container filled with the cement compound, with the filter with the spent sorbent placed inside, was calculated. A technology for processing of liquid radioactive concentrates from the Leipunskii Institute of Energy Physics was suggested and substantiated.     

Potential of thermal treatment for decontamination of mercury containing wastes from chlor-alkali industry

Old dumps of mercury waste sludges from chlor-alkaline industry are an environmental threat if not properly secured. Thermal retortion can be used to remove mercury from such wastes. This treatment reduces the total mercury content, and also may reduce the leachability of the residual mercury. The effects of treatment temperature and treatment time on both residual mercury levels and mercury leachability according to the US EPA TCLP leaching procedure, were investigated. Treatment for 1h at 800°C allowed to quantitatively remove the mercury. Treatment at 400°C and above allowed to decrease the leachable Hg contents to below the US EPA regulations. The ultimate choice of treatment conditions will depend on requirements of further handling options and cost considerations.     

Precipitation of cesium jointly with uranium from nitric acid liquid radioactive wastes to obtain solid matrices for long-term storage

The possibility of converting liquid radioactive wastes containing Cs into chemically and thermodynamically stable compounds, cesium uranates, was examined. Cesium uranate of the composition Cs₄U₅O₁₇ can be prepared by different procedures. The resulting compounds are characterized by fairly low Cs leaching rate, which will probably allow liquid cesium-containing radioactive wastes to be converted to solid matrices of small volume, ensuring long-term storage of cesium-containing wastes.     

Testing and calculating a two-chamber plasma furnace for processing of radioactive wastes

A two-chamber plasma furnace has been tested and the advantages of the processing of radioactive wastes with the use of plasma-thermal technologies have been demonstrated. A model of a plasma furnace for processing of low-and medium-activity radioactive wastes formed in the process of operation of atomic-power and nuclear-industry plants has been developed. The thermal parameters of such a furnace have been calculated. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 3, pp. 569–576, May–June, 2008.     

Development of dense corrosion resistant coatings by an improved HVOF spraying process

For 6 years, we have developed corrosion resistant coatings to protect steel structures in the marine environment by using a thermal spray technique. This paper summarizes the major developments and results obtained. Such a coating requires primarily impermeability and secondarily homogenous and clean microstructure. In order to make denser and highly corrosion resistant coatings, we selected spray materials and improved fabrication processes. HastelloyC was a suitable material for High Velocity Oxy-Fuel (HVOF) spraying to form corrosion resistant coatings because of its high resistance against thermal oxidation as well as seawater corrosion, especially crevice and pitting corrosion. An inert gas shroud system was attached with a commercial HVOF apparatus and this attachment increased the in-flight velocity of spray particles over 750 m s^?1 and simultaneously suppressed oxidation significantly. In addition, some new methods were designed to evaluate the sprayed particle’s state and the coating properties with high accuracy and sensitivity. Thermal energy of in-flight spray particles was revealed by molten fraction of spray particles, determined by quantitative analysis of melted and unmelted particles captured in an agar gel. Through-porosity of the coatings with open porosity below 0.1% was determined by using Inductively Coupled Plasma analysis of dissolved substance from substrate through the penetrating path of the coatings. The coating of HastelloyC nickel base alloy by the HVOF spraying with the gas shroud attachment had zero through-porosity and 0.2 mass% of oxygen content. The laboratory corrosion tests showed that the on-shroud HastelloyC coating was comparable to the bulk material of HastelloyC in terms of corrosion resistance. This coating, formed on steel, demonstrated an excellent protective performance over 10 months in the marine exposure test.     

Development of a process for cesium recovery from the clarified phase of high-level waste storage tanks of the Mayak Production Association with a ferrocyanide sorbent

Batch and column experiments on cesium recovery from the clarified waste of high-level waste storage tanks of the Mayak Production Association using FS-10 ferrocyanide sorbent were performed with model and real solutions. The ferrocyanide sorbent exhibits the required performance in cesium sorption from the solution, ensuring the reduction of the specific activity of the liquid radioactive waste to the values corresponding to intermediate-level waste. In operation in the sorption–desorption–regeneration cycle, 80% of the deposited cesium is removed with the desorbing solution, and the sorption characteristics of FS-10 are reproduced in the second cycle, which suggests the possibility of repeated use of the sorbent.     

热声发动机用声学放大器的改进研究

声学放大器是一种可显著提高热声发动机输出压力振幅和压比的装置,存在的主要问题是声功损失过大.通过理论研究,提出采用较大管径进一步提高声学放大器性能的方法,称为改进型声学放大器.实验结果表明:该声学放大器在大幅度提升输出压比的同时,没有明显降低发动机内的压比和破坏发动机内部声场,能使发动机工作在较高的品质状态.采用变负载法测量声功的实验结果也表明,改进型的声学放大器有效地解决了声功损失过大的问题.     

Kinetic and thermodynamic studies for cesium removal from low-level liquid radioactive waste using impregnated polymeric material

A novel polymeric impregnated material was prepared by loading 4,4′(5′)di-t-butylbenzo-18-crown-6 (DtBB18C6) onto poly(acrylamide-acrylic acid-acrylonitrile)-N,N′-methylenediacrylamide [P(AM-AA-AN)-DAM]. The sorption of ¹³⁷Cs onto P(AM-AA-AN)-DAM/DtBB18C6 was studied using batch equilibrium technique with respect to the pH, contact time, and temperature. The applicability to treatment of low-level liquid radioactive waste was examined. The free energy (ΔG ⁰), enthalpy (ΔH ⁰), and entropy (ΔS ⁰) of the sorption were calculated. These parameters showed that the sorption of ¹³⁷Cs onto P(AM-AA-AN)-DAM/DtBB18C6 was spontaneous and endothermic in nature. The Lagergren first-order, pseudo-second-order, and homogeneous particle diffusion models were tested kinetically to describe the reaction mechanism. The experimental data were fitted well by the pseudo-second-order kinetic model.     

Production of commercial hydrogen and acetylene from propane-butane and liquid hydrocarbons in an electric-arc plasma reactor

A fundamentally new structure of a plasma reactor for production of acetylene and commercial hydrogen from gaseous and liquid hydrocarbons has been developed and proposed. In this device, the plasma jet of synthesis gas is submerged in the volume of liquid hydrocarbons to form a gas volume in which the second stage of pyrolysis reactions is realized. Experimental investigations have been carried out. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 4, pp. 630–636, July–August, 2008.     

Status and Development Prospects of Establishing Reference Tools for Reproducing the Units of Volumetric Activity of Radon and Thoron and Radon Flux Density from the Soil Surface

Measurement Techniques - An approach to creating reference tools for reproducing the units of volumetric activity of radon and thoron and radon flux density from the ground surface based on the...     

Development of sodium propionate-based deep eutectic solvents for polyphenol extraction from onion solid wastes

Clean Technologies and Environmental Policy - The objective of the study presented herein was the optimisation of onion solid waste (OSW) polyphenol extraction, using sodium propionate-based deep...     

Coprecipitation of Pu(IV) with Fe(III) and Cr(III) hydroxides from nitrate-acetate solutions under hydrothermal conditions simulating deep disposal of liquid radioactive wastes

Precipitation of Fe(III), Cr(III), Ni(II), and Mn(II) from nitrate-acetate solutions and coprecipitation of Pu(IV) with Fe(III) and Cr(III) were studied. The degree of precipitation of 80–95% is attained for Fe(III) at 95–200°C and pH>0.5–0.6, and for Cr(III), at T=95°C and pH≥4.0 or T=200°C and pH≥1.0. The phase composition of the precipitates formed by thermal hydrolysis of iron nitrate in model solutions was analyzed. Depending on pH and temperature, the solid phase contains various modifications of Fe₂O₃, FeOOH, and amorphous phases. Noticeable coprecipitation of plutonium from nitrate-acetate solutions is observed at pH≥4, and it is incorporated in the precipitate only at formation of FeOOH. No coprecipitation of Pu(IV) with Fe₂O₃ was found. Under the given experimental conditions, plutonium in aqueous solutions occurs in the oxidation state +4 forming monoacetate (or, probably, hydroxo acetate) complexes.     

Production of composite particles using an innovative continuous dry coating process derived from extrusion

Dry particle coating is used to modify surface properties and monitor the end use properties of powders. These processes are mainly running in batch mode. In certain cases, continuous processes may present interest for specific applications (limitation of investments, stability, versatility…). In this study, the feasibility of dry coating particles by an innovative way derived from the well-known extrusion process was investigated. Adhesion between host and guest particles is induced by mechanical shear stress during processing. A preliminary parametric study on microcrystalline cellulose particles as host particles was carried out in order to determine the operating condition range. Then, coating was successfully performed using talc and a microcrystalline cellulose system, which demonstrates the feasibility of this novel process and led to different morphologies according to the operating conditions.     

油气生产监控系统的开发研究

针对油田油气生产对监控系统的实际需要和目前国内外同类产品在现场应用中存在的问题,开发了一套基于DSP技术和移动数据通信技术(GPRS／CDMA)的远程终端(RTU)和基于WindowsNT(或2000)的生产监控系统软件。系统采用面向对象技术、控件技术、数据压缩技术和移动数据传输技术等多项通讯和控制领域先进的软件开发技术,实现了油气生产控制中心对该抽油井的保护、监视、控制、计量和防盗等功能,对于提高油气生产效率,有效的降低劳动强度,增加效益具有重要的意义。文章介绍了系统的研究开发、系统构成、各部分的功能、生产设计及应用情况。     

液膜法萃取青霉素的研究

介绍了乳状液膜法萃取模拟发酵液中青素的研究工作，考究了混合槽中液膜组成、试剂比、油内比、乳水比及外水相ＰＨ变化对传质过程的影响，找出了一个较为适宜的液膜组成及室浊下适宜操作的萃取工艺条件。     

T - Vmin addressing mode and an improved equivalent circuit model for ferroelectric liquid crystal displays

The authors describe an improved model for modelling the electro-optical response of a ferroelectric liquid crystal display and discuss its applicability. The model includes the direct coupling of applied electric fields to dielectric permittivity, an effect not accounted for in previous equivalent circuits. Compared with previous models, the new model has more capability in optical response prediction and device setup optimisation when the dielectric biaxiality of ferroelectric liquid crystals is of a relatively high value. In the improved model, different trends of switching time are observed as drive voltage rises in cases of positive anisotropy and negative anisotropy. The bend in tau-V_min mode, that is, the minimum pulse area for switching directors, is measured and the mechanism of optical contrast enhancement and switching process complemented by high-frequency ac pulses is clearly explained. Results obtained from the improved model compare favourably with that obtained from numerical models and from testing of a real cell     

Development of an integrated multichannel inlet for improved particle classification in hydrocyclones

The inlet design of hydrocyclones determines the flow field symmetry and facilitates the formation of vortices. In this study, an integrated multichannel inlet based on the Archimedes spiral is developed to improve particle classification by combining the advantages of existing designs. Hydrocyclones with conventional tangent or novel spiral inlets are comparably studied to evaluate the feasibility and superiority of this design using the validated volume of fraction model and two-fluid model. Numerical results show that this novel spiral inlet dramatically improves the flow field symmetry in terms of radial velocity and air core as well as reduces the short-circuit flow and circulation flow. In addition, it also provides strong diversion and pre-separation effects on particles. Consequently, this novel spiral inlet provides superior classification performance than the conventional design, appearing in smaller cut-size, higher cut sharpness, and higher capacity. Such advantages become less evident with increasing channel number, due to the increased turbulence intensity caused by the additional feed streams. The spiral inlet with two channels can largely resemble the design with two tangential inlets in all indices, which makes it the most suitable in this study. This design method can be easily extended to other types of hydrocyclones.     

Study of the discharge process into a liquid of a gas stream from an immersed nozzle

The results of an experimental investigation of the discharge into a liquid of a gas stream from an immersed nozzle, positioned at an arbitrary angle to the surface, are presented. It is assumed that the gas is not dissolved in the liquid, i.e., it is nonassimilable.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 2, pp. 213–223, August, 1977.