Influence of pressure (temperature) on the nitric acid distribution between the liquid and vapor in the course of evaporation of nitric acid radioactive waste

Analysis of the published dependences of the HNO₃ distribution coefficient between the liquid and vapor in the system with water shows that these dependences are power functions with the exponent depending on the temperature (pressure) and emerge from the azeotropic point. The exponent is inversely proportional to the temperature, and its logarithm is directly proportional to the logarithm of the pressure. The pattern is preserved when a salting-out agent is present in the system and is described similarly when taking into account the hydration and hydrolysis of the cation and the degree of dissociation of sulfuric acid, as shown previously for atmospheric pressure. The dependences obtained are interpreted within the framework of the law of mass action (without activity coefficients) as dilution of the azeotropic compound HNO₃(H₂O)₂ with water with the formation of an associated ionic liquid.     

Simulation of the distribution of radionuclides in the reservoir bed for deep-well injection disposal of acid liquid radioactive waste

A mathematical model was developed for describing the changes in the state of the reservoir bed for dee-well injection disposal of acid liquid radioactive waste. The model considers the multicomponent filtration of the solution in the heterogeneous bed, sorption-desorption of radionuclides, taking into account the dependence of the distribution coefficient on the temperature and pH, as well as radioactive decay, interaction of acids with minerals, radiation-chemical and thermochemical decomposition of the acids, and dynamics of the temperature field, taking into account the convective heat transfer, thermal conductivity, and radiogenic heat release. The results of the simulation of the migration of radionuclides were reported, as well as of the distribution of the acids and the dynamics of the temperature field in the vicinity of the injection well of the site for deep-well injection disposal of the waste from Siberian Chemical Combine. A technogenic barrier is formed in the vicinity of the injection well, hindering the spread of radionuclides in the reservoir bed.     

Mass transfer between streams of liquid and vapor during evaporation from capillaries

We have estimated the degree of departure from one-dimensionality of the relative humidity field during evaporation from a capillary, allowing for interaction of the vapor and liquid phases according to the Deryagin-Nerpin-Churaev theory. The boundary conditions for the non-one-dimensional problem have been formulated. An analytical solution has been obtained for a non-one-dimensional relative humidity field in a capillary under simplifying assumptions.     

Treatment of radioactive liquid waste by sorption on natural zeolite in Turkey

Liquid radioactive waste has been generated from the use of radioactive materials in industrial applications, research and medicine in Turkey. Natural zeolites (clinoptilolite) have been studied for the removal of several key radionuclides ((137)Cs, (60)Co, (90)Sr and (110m)Ag) from liquid radioactive waste. The aim of the present study is to investigate effectiveness of zeolite treatment on decontamination factor (DF) in a combined process (chemical precipitation and adsorption) at the laboratory tests and scale up to the waste treatment plant. In this study, sorption and precipitation techniques were adapted to decontamination of liquid low level waste (LLW). Effective decontamination was achieved when sorbents are used during the chemical precipitation. Natural zeolite samples were taken from different zeolite formations in Turkey. Comparison of the ion-exchange properties of zeolite minerals from different formations shows that Gordes clinoptilolite was the most suitable natural sorbent for radionuclides under dynamic treatment conditions and as an additive for chemical precipitation process. Clinoptilolite were shown to have a high selectivity for (137)Cs and (110m)Ag as sorbent. In the absence of potassium ions, native clinoptilolite removed (60)Co and (90)Sr very effectively from the liquid waste. In the end of this liquid waste treatment, decontamination factor was provided as 430 by using 0.5 mm clinoptilolite at 30 degrees C.     

The atom velocity distribution function in the process of liquid evaporation

Analytical expressions determining the velocity distribution function of evaporating particles were obtained for evaporation into vacuum. The formulas are compared with numerical simulation results; the coincidence can be treated as sufficiently good. The particle distribution function over the longitudinal, i.e., directed from evaporation surface, velocity turns out to be significantly non-Maxwellian. The distribution function over the transverse projections of the velocity is Maxwellian but with a distribution modulus different from the evaporating liquid temperature T. The mean energy of a particle escaping from the surface is 2kT.     

Inorganic sorbents based on modified microspheres for treatment of liquid radioactive waste

Sorbents based on hollow microspheres of entrained ash, with the surface modified by various chemical compounds (ferrocyanides, phosphates, oxides, etc.), were synthesized. Their physical and ion-exchange characteristics were examined. These sorbents show promise for treatment of low-and intermediate-level liquid waste of various origins in the dynamic and static sorption modes. The use of microspheres as matrices is not only technically but also environmentally efficient, because waste from thermal power engineering is utilized for disposal of nuclear waste. Original Russian Text L.D. Danilin, V.S. Drozhzhin, 2007, published in Radiokhimiya, 2007, Vol. 49, No. 3, pp. 283–286.     

Role of simple anionic ligands in deep decontamination of liquid radioactive waste

The influence of the NO₉^-, SO₄^2–, HCO₃^–, and Ac^– anions on the efficiency of the sorption of bivalent metals by sulfonic cation exchangers was studied. The main method was elution of the Mg²⁺, Ca²⁺, and Co²⁺ cations with individual solutions of the corresponding sodium salts and their mixed solutions with sodium nitrate from the Dowex-50 ion-exchange resin at fixed temperatures. The exchange efficiency is influenced both by neutral complexes of the metal cations mainly with inorganic acid ligands and by the single-charged species. The latter species affect the efficiency of the ion-exchange waste reprocessing considerably more strongly. An increase in the temperature of the solution being treated leads to a significant shift of the peak position toward larger retention volumes, which indicates that it is appropriate to perform the water treatment on sulfonic cation exchangers at elevated temperatures. The first formation constant of the single-charged cobalt dihydrogen phosphate complex species at an ionic strength of 0 M was obtained: logK₁(CoH₂PO₄⁺) = 1.36.     

Effect of the temperature on the evaporation of liquid droplets in an air stream

Results are shown of a study concerning the evaporation of tetrafluorodibromomethane within a temperature range from –14 to + 750°C.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 4, pp. 686–691, October, 1972.     

Effect of biogeochemical factors on the Np(V) mobility under the conditions of remote zone of deep liquid radioactive waste repositories

Under the conditions of remote zone of deep liquid radioactive waste repositories (Eh of pore waters from −60 to 186 mV), Np occurs in oxidation states (V) and (IV) on mineral particles incorporated in surrounding rocks. Np(V) can be additionally sorbed on newly formed Fe oxide-hydroxide phases and on Fe(II)-containing minerals owing to the sorption of the reduced forms. The fraction of Np forms tightly fixed on the rock increases with time. Shewanella putrefaciens microorganisms and sulfate-reducing bacteria isolated from deep liquid radioactive wastes repositories reduce Np(V) under anaerobic conditions. The addition to S. putrefaciens culture medium of the rock from the horizon in which the deep liquid radioactive waste repository is arranged leads to deposition of a significant fraction of Np(IV) and Np(V) on the microbial biomass and rock. In the presence of nitrates, the fraction of the reduced Np fixed on the rock considerably decreases. Sulfate-reducing bacteria reduce Np(V) with the released hydrogen sulfide and, probably, in a dissimilation process. The results obtained demonstrate the possibility of biogenic and abiogenic reduction of Np in deep liquid radioactive waste repositories, which will lead to a decrease in the Np(V) mobility.     

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.     

青梅腌制废液中氢氰酸的处理

青梅腌制废液中含有苦杏仁甙水解后产生的剧毒物质氢氰酸,本文采用氢氧化钾和次氯酸钙处理腌制废液中的氢氰酸。处理试验室腌制一年的青梅腌制废液100mL,需要氢氧化钾4.1g,次氯酸钙0.33g。处理后腌制废液中总氰化合物的浓度为0.43mg/L,符合GB8978-1996《污水综合排放标准》表4中二级标准限值(0.5mg/L)。     

An investigation of the evaporation of drops in superheated vapor

A model of the evaporation of drops in the spray cone is proposed. A system of equations for calculation of the main characteristics of the spray cone is derived.     

Decontamination of uranium-contaminated waste oil using supercritical fluid and nitric acid

The waste oil used in nuclear fuel processing is contaminated with uranium because of its contact with materials or environments containing uranium. Under current law, waste oil that has been contaminated with uranium is very difficult to dispose of at a radioactive waste disposal site. To dispose of the uranium-contaminated waste oil, the uranium was separated from the contaminated waste oil. Supercritical R-22 is an excellent solvent for extracting clean oil from uranium-contaminated waste oil. The critical temperature of R-22 is 96.15 °C and the critical pressure is 49.9 bar. In this study, a process to remove uranium from the uranium-contaminated waste oil using supercritical R-22 was developed. The waste oil has a small amount of additives containing N, S or P, such as amines, dithiocarbamates and dialkyldithiophosphates. It seems that these organic additives form uranium-combined compounds. For this reason, dissolution of uranium from the uranium-combined compounds using nitric acid was needed. The efficiency of the removal of uranium from the uranium-contaminated waste oil using supercritical R-22 extraction and nitric acid treatment was determined.     

Effect of thermal annealing on properties of borobasalt systems containing radioactive waste fractions

The effect of thermal annealing on the resistance of borosilicate systems to crystallization and the effect of this process on the hydrolytic stability of the materials were examined. The systems containing REE + TUE and Cs + Sr fractions were studied. For borobasalt matrices containing the REE + TUE fraction, annealing in the temperature rangte 400–600°C leads to an appreciable decrease in the leach rate in water. For the borobasalt system containing waste components of the Cs + Sr fraction, changes in the leach rate upon thermal annealing are not clearly observed up to the annealing temperature of 600°C.     

Effect of thermal annealing on the properties of boron-containing basalt systems containing radioactive waste components

The effect of thermal annealing on the resistance of borosilicate systems to crystallization and on the hydrolytic resistance of the materials was examined. The systems containing individual components of radioactive wastes of both REE + TUE and, for comparison, Cs + Sr fractions were examined. Under the experimental conditions (annealing temperature 800°C, time 100 h), the materials of all the examined compositions crystallize to certain extent. The matrices incorporating REE crystallize to the least extent. In all the cases, the crystalline phase contains mainly compounds of the component being incorporated and also Fe compounds. A distinctive feature of the matrices containing lanthanide oxide and of the boron-containing basalt matrix itself is increased resistance to leaching in water after annealing in the temperature range 400–500°C.     

气液两用槽车设计制造中应着重考虑的一些问题

根据某型高压低温充氧车的研制实践,对氧、氮气液两用槽车的贮槽与贮气瓶的配置、低温液体贮槽蒸发率的要求及控制、低温液体泵的安装及工作条件的保障以及槽车安全性设计等方面应重点考虑的问题进行了探讨。     

Interaction of plutonium with iron- and chromium-containing precipitates under the conditions of reservoir bed for liquid radioactive waste

The behavior of Pu under the conditions of liquid radioactive waste (LRW) disposal in a reservoir bed was studied. The pH dependence of the Pu sorption is the same in the cases when the radionuclide is introduced together with the simulated LRW solution or after the precipitate formation. The composition and morphology of Fe,Cr-containing precipitates formed under the conditions simulating the radioactive waste disposal were determined. The solid phase was characterized by X-ray diffraction analysis and by transmission and scanning electron microscopy. The phase composition of the precipitates was determined in relation to the presence of acetate ions, Fe concentration in the solution, and storage time and temperature. The main phases formed are ferrihydrite, goethite, hematite, and grimaldiite.     

叶片对铝铅合金液中铅分布的影响

针对铝铅合金液电磁搅拌中存在的重金属铅偏聚问题,在常规电磁搅拌方法基础上,利用自行设计的内壁布有直叶片坩埚,对铝铅合金液进行了电磁-叶片搅拌研究,采用多点冷淬方法,得到了叶片布置角度对铝铅合金液内铅分布的影响规律,确定了铅分布均匀的铝铅合金液的电磁-叶片搅拌技术.结果表明:叶片与坩埚径向夹角β决定着铅在坩埚径向上的分布,叶片与坩埚轴向夹角γ决定着铅在坩埚轴向上的分布,当β为35°、γ为25°时,可得到铅在坩埚径向上和轴向上都分布均匀的Al-28%Pb合金液,显著地提高了铸造Al-28%Pb合金材料的性能.