Effect of plate aspect ratio on the recovery of deuterium from water-isotope mixture in flat-plate thermal diffusion columns with transverse sampling streams

The optimal plate aspect ratios for the best recovery of deuterium from water-isotope mixture in flat-plate thermal diffusion columns with transverse sampling streams have been determined. The maximum recovery and maximum production rate are achieved without changing the total expenditure, while the design with minimum plate surface area results in minimizing the total expense.     

Influence of the surface conditions on permeation in the deuterium–MANET system

The condition of the surfaces is of crucial importance for the deuterium permeation through materials. In this work a study of the surface constants for the adsorption (σk₁) and release (σk₂) of deuterium under different surface conditions on the martensitic steel DIN 1.4914 (MANET) has been carried out. The growth of an oxide surface layer (Cr₂O₃) of about 25–30 nm in a MANET sample, heat treated in an oxidizing environment, compared to the bare MANET that have a ‘natural' oxide of about 5 nm has provoked a reduction of both the permeation rate and the recombination coefficient (about 3 orders of magnitude). In addition, the permeation governing process has changed from diffusion-limited to surface-limited. The measurements of the permeation rate of deuterium were performed by a gas-phase permeation technique over the temperature range 574–746 K and for deuterium driving pressures in the range from 3 to 10⁵ Pa.     

APPLICATION OF SITE-SPECIFIC NATURAL ISOTOPE FRACTIONATION (SNIF-NMR) OF HYDROGEN TO THE CHARACTERIZATION OF EUROPEAN BEERS

More than one hundred samples of European beers have been investigated by the new SNIF-NMR method which is based on 2H NMR at the natural abundance level and enables site-specific natural isotope fractionation factors in ethanol to be determined. The relative (R) and absolute (D/H)_i, parameters are shown to be characteristic of the country where the beers are brewed and the observed variations are explained in terms of cereal composition, water resource, and manufacturing processing (fermentation, yeast, temperature cycle). These new parameters find analytical and mechanistic applications in the identification of a beer and in the investigation of a fermentation process.     

Characterization and modeling of diffusion process for mass transport through the Tournemire argillites (Aveyron, France)

Argillites are one of the geological formations studied by IRSN for their confining properties for isolation of radioactive wastes. One of the main objectives is the study of water transport through rocks with very low water content and very low hydraulic conductivity by modeling of natural tracer profiles. This paper presents the protocol developed for and applied to the acquisition of data for chloride content in interstitial water of the Toarcian argillites at the Tournemire site (Southern France). This protocol is based on laboratory diffusion experiments and on modeling. Experimental data obtained during the transient and steady-state parts of diffusion experiments enable, respectively, the assessment of the diffusion coefficient and the determination of Cl concentration in pore water. Using this protocol, profiles with depth for both of these data sets have been acquired along the geological sequence. Taking into account the present knowledge of the geological and hydrogeological history of the Tournemire massif, a conceptual model granting the main role for mass transport to diffusion has been proposed. According to this conceptual model, a one-dimensional numerical model was built for simulating the mass transport of chloride through the sedimentary column, over 53 Ma. The good agreement between experimental data and calculated values for both diffusion coefficients and concentrations of chloride confirms that diffusion is likely the main process for mass transport in the massif. This model was also tested with the deuterium content of interstitial water, applying variable concentrations at the aquifer system boundaries for reflecting the thermal dependency of isotopic composition in precipitation. These simulations also reveal the likely important role of heterogeneities, such as fractures, in the variability of tracer concentrations with regards to a simple diffusion profile.     

Reactivity and deuterium retention properties of titanium-beryllium intermetallic compounds

Beryllium intermetallic compounds (beryllides), such as Be₁₂Ti and Be₁₂V, are the most promising advanced neutron multipliers in demonstration (DEMO) fusion power reactors because of higher stability, lower retention, and swelling. The advanced neutron multipliers are being developed by Japan and the EU as a framework of Broader Approach (BA) activities, targeted at broadening the research fields to not only establish fabrication methods but also for their characterization. Our group has proposed a plasma sintering method for the synthesis of beryllides. When the mixed powder was plasma-sintered at the beginning of the experiment, consolidation of the target composition was so insufficient that single-phase beryllides could not be synthesized. In order to obtain single-phase beryllides, an additional homogenization treatment of the sintered beryllides at 1473 K was necessary, resulting in increased porosity. Using the homogenized powder as the starting material, single-phase Be₁₂Ti and Be₁₇Ti₂ intermetallic compounds were successfully synthesized. As experimental results, the hardness of the compounds was relatively low owing to low sintering density. In addition, the oxidation behavior of the beryllides, when exposed to 15% H₂O/Ar at high temperatures, were investigated and the results indicate the presence, gray colored Be oxide formed on the surface in Be₁₂Ti tested at above 1073 K and Be oxide with a small fraction of white colored Ti oxide even tested at 873 K in Be₁₇Ti₂ phase resulting in the bigger increase of the weight gain than Be₁₂Ti. In addition, this oxidation occurring at lower temperature can be reasoned by the assumption that the existence of BeO (=oxygen content) in Be₁₂Ti (1.95%) and Be₁₇Ti₂ (2.95%) may facilitate increased reactivity. Furthermore, thermal expansion of Be₁₇Ti₂ was found out to be bigger than that of Be₁₂Ti because Be₁₇Ti₂ has more complex crystal structure and higher melting temperature. In terms of deuterium desorption and retention properties, the maximum peaks are detected around 600 K in beryllides, while those in beryllium occur at 800 and 980 K. From the comparison of deuterium retention, it was obvious that Be₁₇Ti₂ has a lower retention than Be₁₂Ti, while Be has the highest value.     

Influence of the grain structure of yttria thin films on the hydrogen isotope permeation

Steel components are required in the infrastructure and the facilities of the hydrogen economy. The high hydrogen pressures in the hydrogen economy lead to embrittlement and surface corrosion of the steels. For the functionality of the facilities it is necessary to suppress the embrittlement and the surface corrosion of the steels by protective layers, e.g. ceramic thin films. With regard to fusion power plants ceramic thin films on the structural steel materials are also required. These thin films work as a tritium permeation barrier that is necessary to prevent the loss of the radioactive fuel inventory. Oxide thin films, e.g. Al₂O₃, Er₂O₃, and Y₂O₃, are promising candidates as tritium permeation barrier layers. In terms of the application in the first wall, this is especially true for yttrium due to its favorably short decay time after neutron activation compared to the other candidates. The Y₂O₃ layers with thicknesses of 0.5 μm–1 μm are deposited on both substrate sides by RF magnetron sputter deposition. Since the microstructure of the barrier layer plays an important role for the permeation reduction, layers with three different magnetron process modes and thus three different microstructures are prepared. After annealing the cubic crystal structure of all thin films is verified by X-ray diffraction and the different microstructures are investigated by scanning electron microscopy and transmission electron microscopy. The Y₂O₃ stoichiometry of all thin films and a chromium oxide material segregation at the interface are verified by analysis methods such as X-ray photoelectron spectroscopy. The permeation reduction factors of all thin films are determined in gas-driven deuterium permeation experiments. Corresponding to the three different microstructures, reduction factors of 25, 45, and 1100 are identified. Thus, the permeation reduction is strongly dependent on the Y₂O₃ microstructure. The measurement results suggest that a high density of grain boundaries leads to a high hydrogen permeation.     

Radiation induced deuterium absorption for RB-SiC,HP-SiC,silicon and graphite loaded during electron irradiation

Absorption, diffusion, and desorption of hydrogen isotopes are expected to occur during operation in future fusion reactors and these processes will strongly depend on the irradiation conditions, neutron flux and purely ionizing radiation. The main aim of the work is to address the electron irradiation induced absorption of hydrogen isotopes in RB-SiC. Deuterium loading was carried out with both the sample and the surrounding deuterium gas exposed to 1.8 MeV electron irradiation in order to evaluate the radiation enhanced deuterium absorption. Thermo stimulated desorption (TSD) measurements were carried out for both electron irradiated and unirradiated samples in order to evaluate the possible radiation enhanced retention of the previously loaded deuterium. The materials subjected to the deuterium loading process were also studied by SIMS. Noticeable radiation enhanced deuterium absorption was observed. Most of the deuterium absorbed during irradiation was thermally released at about 600 °C.     

Improvement in deuterium recovery from water–isotope mixture by thermal diffusion in the device of branch columns

Deuterium recovery from water–isotopes mixture using thermal diffusion can be improved by employing the branch column device, instead of single column devices, with the same total column length. The remixing effect due to convection currents in a thermal diffusion column for heavy water enrichment is thus reduced and separation improvement increases when the flow rate or the total column length increases. The improvement in separation can reach about 50% for the numerical example given.     

氮杂环苯基吡啶类铱配合物合成及器件性能

通过对2-甲基-8-(2-吡啶基)苯并呋喃[2,3-B]吡啶辅助配体进行修饰,在吡啶的4号位引入吸电子基团苯基,并对其进行全氘代,同时对5-甲基-2-对甲苯基吡啶主配体的两个甲基进行全氘代,分别合成了两种铱磷光配合物Ⅳ和Ⅳ-d₂₀,采用元素分析、质谱和核磁共振氢谱对其结构进行了表征与确认。利用UV-Vis 光谱、荧光发射光谱(PL)和循环伏安法对其光物理性质及能级结构进行了研究。结果表明：铱配合物的Ⅳ和Ⅳ-d₂₀光致发光光谱发射波长分别为546.85nm和548nm;它们的HOMO和LUMO能级分别为-5.237ev和-2.645ev、-5.082ev和-2.50ev,都是潜在的黄绿色磷光材料。以铱配合物Ⅳ和Ⅳ-d₂₀为客体,制备了结构为ITO/HT:NDP-9(100nm,2%)/HT(130nm)/EB(10nm)/GH:化合物Ⅳ或Ⅳ-d₂₀(40nm,5%)/HB(10nm)/ ET:Liq(35nm,50%)/Liq(10nm)/Al(150nm)的OLED器件,并研究了它们的器件性能。结果表明：铱配合物Ⅳ-d₂₀表现出更优异的器件性能。电流密度为20mA/cm₂^时,铱配合物Ⅳ-d₂₀的器件发射波长为552nm,CIE 坐标为 (0.422,0.569),电流效率为 87.00cd/A,外量子效率(EQE)高达23.82%。     

Ti/AlN/Ti/AlN复合涂层的制备和阻氘性能研究

为提高AlN涂层的稳定性和阻氚性能,提出“Ti-AlN”复合结构涂层。采用磁控溅射法在316L不锈钢基体表面制备了结构致密、总厚度约500 nm的Ti/AlN/Ti/AlN复合涂层。对涂层样品进行不同的真空热处理后,采用SEM、XRD、AES等手段分析涂层样品在热处理前后的微观形貌和结构变化,并对样品在200-600 ℃的阻氘性能进行测试和分析。结果表明,仅热处理温度为760 ℃时,Ti-AlN界面反应生成少量的Al3Ti相。在所有涂层样品中,热处理温度为700 ℃、升温速率为1.5 ℃/min的复合涂层表现出最优的阻氘性能,其600 ℃的PRF（Permeation Reduction Factor）高达536。当热处理温度升高至760 ℃或升温速率达到2.5 ℃/min时,表层AlN层的开裂程度更为严重,并导致涂层的阻氘性能显著降低。另外,所有涂层样品的PRF（阻氘性能）均随渗透温度的降低而急剧减小,表明氘气渗透过程中的温度变化会导致复合涂层阻氘性能失效。