Vitrification of a high-level iron-aluminate wastes simulator in a cold crucible

An increase of the water content of a simulator of sludges from the test area at the Savannah River Plant (USA) which are vitrified in a cold crucible with inner diameter 236 mm from 50 to 70 wt % results in a substantial reduction of the mass loading rate of the sludge, production of molten glass, and specific production of the glass product. The specific energy expenditures on vitrification increase by more than a factor of 2. The formation of an undesirable nepheline phase is observed in samples containing more than 60 wt % wastes simulator. The chemical stability of the glass product remains high even when its wastessimulator content is 65 wt %.     

Vitrification of a surrogate for high-level wastes from the Savannah River plant (USA) on a cold-crucible bench facility

Two experiments on the vitrification of a surrogate for the wastes from the Savannah River plant (USA) have been performed on a cold-crucible (inner diameter 216 mm) induction-melting bench facility at the Moscow Scientific and Industrial Association Radon (1.76 MHz, 60 kW). To obtain borosilicate glasses with two compositions containing 45 mass % oxides of the wastes (computed) a slurry with moisture content about 60 mass % and a mixture of reagents as the glass-forming additives gave a mass velocity of the slip 8 kg/h on average, glass output about 2 kg/h, and specific glass product rate about 47 kg/(m²·h). The specific energy consumption was 20 k·W·h/kg. It was shown that the mass velocity of the slip can be increased to 18 kg/h. Switching to glass-forming additives consisting of the special borosilicate frit-200 and-320 and lowering the water content in the slurry to 25–30 mass % increases the productivity of the process by 15–35%. The specific glass production rate reaches 100 kg/(m²·h). The glasses produced contained a small quantity of a magnetitic spinel phase. __________ Translated from Atomnaya énergiya, Vol. 102, No. 4, pp. 225–232, April, 2007.     

Vitrification of a surrogate for high-level wastes from the Savannah River facility (USA) in a commercial cold-crucible facility

Experiments on vitrifying a surrogate for SB2 pulp from the Savannah River facility (USA) in a cold crucible with inner diameter 418 mm in a commercial facility for vitrifying medium-level wastes at the Moscow Scientific and Industrial Association Radon are performed. Borosilicate glass materials, containing 50 mass % oxides of the wastes, including a magnetitic spinel phase in amounts not exceeding 15 vol. %, are obtained. The maximum mass average velocity of the slurry load and the melt output reach 40 and 16 kg/h, respectively. This corresponds to maximum specific vitrified wastes production capacity 2830 kg/(m²·day). The specific energy consumption for obtaining the glass product is about 10 kW·h/kg, which is approximately half the level for reprocessing slurries in crucibles with half the diameter. The chemical stability of the glass materials is 10–50 times higher than that of the materials made from glasses recommended by the US Environmental Protection Agency. __________ Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 296–299, May, 2007.     

Investigation of the behavior of platinum-group elements during vitrification of model high-level wastes in application to an induction melter with a cold crucible

Conclusions In the process of vitrification of high-level wastes the platinum-group elements form at the calcination stage phases which have a limited solubility in the glass melts. If the dissolved part of the platinum-group elements, which at 1200–1300°C does not form more than 30% of their total concentration in the melt [3], is neglected, then apparently it can be assumed that the behavior of the dispersed particles of the platinum-group elements is determined by their thermodynamic stability, interaction with one another, and sedimentation, and the melts of the phosphate and borosilicate glasses play the role of an inert medium. Ruthenium dioxide and the solid solutions based on it, which contain up to 1.5% Ru, Rh, and Pd, are stable up to 1500°C. In the temperature range 1050–1200°C rhodium oxide and the solid solutions based on it, decompose and form metallic rhodium. Metallic palladium apparently forms at 800–900°C. In ceramic melters the temperature of the glass melt is equal to the temperature of the dispersed particles and the composition of the heterogeneous phase based on the platinum-group elements will be determined by the temperature chosen for performing the vitrification process. Induction heating results in local overheating of the electrically conducting dispersed particles by the high-frequency field and, irrespective of the process temperature, in the melt it forms alloys based on platinum-group elements. In summary, the local temperature of the dispersed particles will determine their phase composition, their density, and ultimately their rate of sedimentation and accumulation at the bottom of the melters. State Science Center of the Russian Federation A. A. Bochvar All-Union Scientific-Research Institute of Standardization in Machine Engineering. Translated from Atomnaya énergiya, Vol. 79, No. 1, pp. 34–37, July, 1995.     

用季胺7402从模拟高放废液中分离纯化~(99)Tc

本文研究了一种反相分配色层法分离锝和钌的方法。应用季胺7402从模拟高放废液中提取裂变产物~(99)Tc。方法对得的选择性高,对钌的去污能力强。实验表明:~(99)Tc的回收率达98％,~(103)Ru的去污系数达1×10~3。同时能对钌载体进行分光光度法测定。     

用正电子湮没技术研究新型高临界温度T_c超导材料Ba-Y-Cu氧化物

本文介绍用正电子湮没技术研究了具有高临界温度下T_c的新型超导材料Ba-Y-Cu氧化物。实验发现,在起始转变温度以下,正电子寿命减少与电阻随温度的变化曲线符合。在临界温度T_c处,出现了正电子寿命峰。     

Boron lattice site location in (BGa)As and (BGa)P thin films studied using RBS and NRA with a channeled He+ ion beam

In this study the boron lattice site location in ternary B_xGa_1?xAs and B_xGa_1?xP thin films grown on (0 0 1) GaAs and (0 0 1) GaP, respectively, using low pressure metal-organic vapour-phase epitaxy (MOVPE) with boron concentrations between x = 0.8% and x = 3.2% was investigated with RBS and the ¹⁰B(α,p)¹³C nuclear reaction using a 2.3 MeV He⁺ ion beam. For this purpose, the ion beam was aligned with the [0 0 1], [0 1 1] and [1 1 1] axis and the RBS and proton yield from the nuclear reaction compared with random ion incidence. For comparison, theoretical proton yields which assume boron to be located on substitutional lattice sites only were calculated for each sample/axis combination and compared with the experimental yields. The RBS/channeling measurements show a very good crystal quality of the films with χ_min being in the range of 3–5% for the [0 1 1] axis. The best crystal qualities, i.e. the lowest χ_min values and dechanneling rates, are achieved for low boron concentrations. From NRA/channeling it can be deduced that in the B_xGa_1?xAs films the fraction of interstitial boron is approximately 5% for low boron concentrations of x = 1% and 6–10% for concentrations up to x = 3.2%, whereas the fraction of interstitial boron is less than 3% in the B_xGa_1?xP film studied despite a concentration of x = 2.0%. This indicates that antisite effects of the boron incorporation are more likely in GaAs compared to GaP.     

Spectroscopic studies of homogeneous thin carbon erosion films on mirrors and flakes with a high deuterium content formed in tokamak T-10

Redeposited hydrocarbon films on plasma facing elements in tokamaks accumulate hydrogen isotopes. In the present study such films were made to redeposit on stainless steel mirror substrates as thin films and without any substrate as bare flakes with high deuterium content, under deuterium-plasma discharges inside T-10 tokamak vacuum chamber. These films were subjected to spectral characterizations through Fourier-transform infrared (FT-IR), electron paramagnetic resonance (EPR), and photoluminescence techniques. IR spectra showed the presence of two main deuterium states as observed by the CD_2,3 sp³ stretching modes at 2100–2200 cm⁻¹ and the CD₂ sp³ bending modes at 600–1100 cm⁻¹. Among these, CD₃ stretching mode at 2217 cm⁻¹ may serve as a control for deuterium desorption during the cleanup process of the reactor. As a comparative measure, C60 films were also studied, the luminescence excitation spectrum of which showed similarity in peak positions with tokamak bare flakes pertained to sp² luminescence centers. The observed spectral differences are mainly due to more localized sp² states for C60 and sp³ states for tokamak flakes. EPR spectra of the bare flakes showed the defective states with a high spin density, ∼10¹⁹ cm⁻³ which serve as luminescence quenching centers, and provide a path for hydrogen isotopes adsorption.     

Isotopic composition and residual heat release of oxide fuel with a high americium content after irradiation in bor-60

Calculations of the isotopic composition, residual heat release, and helium content in mixed oxide fuel with a high americium content during a run and during prolonged cooldown were performed for a BOR-60 fast reactor as part of the preparation for the experimental program RETSIKL. The fuel composition consisted of 75% enriched uranium and 20 or 50% by mass of americium-curium fraction and rare-earth elements of spent VVéR-1000 fuel (burnup 40 GW-daylton, 10 year holding period). The americium transmutation rate is about 16.5% for the reactor run, the mass of the accumulated curium is about 13% of the mass of the transmuted americium, the plutonium mass is 35–45% of the latter (almost all on the plutonium consists of nonfissioning isotopes). The total helium accumulation can reach 1 kg/ton of heavy metals. The residual heat release due to α decay²⁴²Cm in about 1 month is ∼1 MW/ton, which has important consequences for planned or emergency shutdown of a reactor. 1 figure, 5 tables, 3 references. Federal Science Center of the Russian Federation-A.I. Leipunskii Physics and Power-Engineering Institute. Translated from Atomnaya énergiya, Vol. 87, No. 5, pp. 360–365, November, 1999.     

Preparation of potassium iron(III) hexacyanoferrate(II) supported on activated carbon and Cs uptake performance of the adsorbent

Synthesis of potassium iron(III) hexacyanoferrate(II) (K/Fe-Fe(CN)₆) in the pores of activated carbon (AC) was attempted by impregnating AC with K₄[Fe(CN)₆] and FeCl₃, and the Cs uptake performance of the resulting adsorbent was examined. K/Fe-Fe(CN)₆ supported on AC was prepared by varying the reaction conditions such as the supplied amounts and molar ratios of the reagents, and the Cs uptake performance was optimized. The impregnated product was characterized by XRD, EPMA, and porosimetry to elucidate the condition to which Fe₄[Fe(CN)₆]₃ was filled in the AC pores. The K/Fe-Fe(CN)₆-on-AC was immersed in seawater containing 0.075 mmol · dm^?3 Cs and agitated for 1 day to obtain the Cs uptake. The Cs uptake was large at pH < 10 but decreased abruptly at pH > 10.5. The maximum Cs uptake was 10.4 μmol · g^?1 at the equilibrium Cs concentration of 49 μmol · dm^?3 and the distribution coefficient was 45.5 dm³ · g^?1 at the equilibrium concentration of 0.015 μmol · dm^?3, respectively. When K/Fe-Fe(CN)₆-on-AC was immersed in Cs-containing seawater, K⁺ ions in the adsorbent were completely exchanged for Na⁺ ions in seawater, and the added Cs⁺ ions were then substituted for the Na⁺ ions in the adsorbent.     

Specifications of nanosecond laser ablation with solid targets,aluminum, silicon rubber,and polymethylmethacrylate (PMMA)

The ablation parameters such as threshold fluence, etch depth, ablation rate and the effect of material targets were investigated under the interaction of laser pulse with low intensity. The parameters of the laser system are: laser pulse energy in the range of 110–140 m J, wavelength1064 nm and pulse duration 20 ns. By macroscopic estimation of the outward images of the ablation and data obtained, we can conclude that the photothermal and photoionization processes have more influence for aluminum ablation. In contrast, for polymer samples, from the macroscopic observation of the border pattern at the irradiated spot, and also the data obtained from the experiment results, we deduce that both chemical change due to heating and photochemical dissociation were effective mechanisms of ablation. However, concerning the two polymer samples, apart from considering the same theoretical ablation model, it is conceived that the photomehanical specifications of PMMA are involved in the ablation parameters. The threshold fluence for an ablation rate of 30 laser shots were obtained as 12.4, 24.64, and 11.71 J cm~(-2), for aluminum, silicon rubber and polymethylmethacrylate(PMMA) respectively.The ablation rate is exponentially decreased by the laser-shot number, especially for aluminum.Furthermore, the etch depth after 30 laser shots was measured as 180, 630 and 870 μm, for aluminum, silicon rubber and PMMA, respectively.     

The impact of cold atmospheric pressure plasma jet on seed germination and seedlings growth of fenugreek(Trigonella foenum-graecum)

The effects of cold atmospheric-pressure plasma jet(CAPPJ) were investigated on germination and early seedling growth of fenugreek(Trigonella foenum-graecum L) seeds.A two-electrode argon CAPPJ system with and without an additional grounded electrode [accelerating grounded(AG) electrode] was used at different exposure times.After 16 h of observation,the germination rates increased by 4 and 7 times,without and with using an AG electrode,respectively,for 1 min of plasma exposure.An increase in shoot fresh weight was observed,especially at 10 min exposure time.A high dry weight of root and shoot at 1 min-AG exposure time was observed.The root:shoot ratio was lower in plasma-treated seedlings,compared with the control plants.The study found that the O-radical emission line(777.4 nm) enhanced 5 times,due to the presence of an AG electrode,which increased the axial electric field and led to the formation of more streamers.The three stated effects(O-radicals,enhancement of the electric field and streamers) could be the cause for the stimulation of seed germination and seedling growth parameters when using the CAPPJ.The scanning electron microscope images showed the etching of the seed surface layers,which was more pronounced when an AG electrode was applied.The results of the current study indicate that the germination rates increased due to the increase of O-radical concentration and the etching of the seed surfaces.     

Extraction of U（VI） and Th（IV） with a novel extractant N,N‘—tetrahexylmalonamide （THMA） in toluene

The dependence of THMA extraction behaviour for U(VI) and Th(IV) on nitric acid concentration,THMA concentratioin and molecular structure of extracted complex has been studied.For nitric acid solutions of 3.0 mol/L a coordinative mechanism may possibly dominate in the extraction of metal catioins,The complex composition of UO2(NO3)2(THMA)2,Th(NO3)4(THMA)2 and Th(NO3)4(THMA03 are proved.     

Applications of cold atmospheric plasmas (CAPs) in agriculture: a brief review and the novel development of a radio-frequency CAP jet generator for plant mutation

Cold atmospheric plasmas (CAPs) have shown great applicability in agriculture. Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases. We briefly review the state-of-the-art stimulating effects of atmospheric-pressure dielectric-barrier-discharge (AP-DBD) plasmas, after the direct or indirect treatment of plants for growth promotion and disease control. We then discuss the special demands on the characteristics of the CAP sources for their applications in plant mutation breeding. An atmospheric and room temperature plasma (ARTP) jet generator with a large plasma irradiation area, a high enough concentration of chemically reactive species and a low gas temperature is designed for direct plant mutagenesis. Experimental measurements of the electrical, thermal and optical features of the ARTP generator are conducted. Then, an ARTP-P (ARTP for plant mutagenesis) mutation breeding machine is developed, and a typical case of plant mutation breeding by the ARTP-P mutation machine is presented using Coreopsis tinctoria Nutt. seeds. Physical and agricultural experiments show that the newly-developed ARTP-P mutation breeding machine with a large irradiation area can generate uniform CAP jets with high concentrations of chemically reactive species and mild gas temperatures, and have significant mutagenesis effects on the Coreopsis tinctoria Nutt. seeds. The ARTP-P mutation breeding machine may provide a platform for systematic studies on mutation mechanisms and results for various plant seeds under different operating conditions in future research.     

Measurement of time varying thickness of liquid film flowing with high speed gas flow by a constant electric current method (CECM)

A constant-electric-current method (CECM) developed by the present author is a kind of conductance method. The characteristics of the CECM are (1) a constant-current power source is used for supplying the electric power and (2) two kinds of electrodes are installed. One is used for supplying electric power and the other is for detecting the information of hold-up or film thickness. The main merits of the CECM are (1) the output from the sensor electrode is independent of the location of gas phase, for example radial location in a tube cross-section, (2) the sensitivity of detecting the change in the hold-up is higher in the case of the thinner film thickness, and (3) the interaction among the electrodes is negligible. The basic idea, calibration and examples of the application of the CECM will be discussed in the present paper.