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。     

DI-B experiment: planning, design and performance of an in situ diffusion experiment in the Opalinus Clay formation

The DI-B experiment is a long-term, natural-scale, in situ diffusion experiment, which is being performed in the Opalinus Clay formation at the Mont Terri Underground Rock Laboratory (URL), in Switzerland, employing nonradioactive tracers. One of the key aspects to be addressed for nuclear waste repository safety assessment purposes is the understanding of the transport mechanisms of the radionuclides contained in the radioactive waste. Consolidated clay formations display very low water hydraulic conductivities, so it is expected that the predominant transport process will be diffusion.The experimental set-up has been designed to withstand the site conditions and for monitoring and recording several physicochemical parameters (pH, conductivity, oxidation–reduction potential), as well as the pressures in the circuit and for the long-distance monitoring of the data acquisition system.The tracer selection has been made based on previous investigations carried out at CIEMAT, including a literature survey, laboratory sorption experiments and hydrogeochemical modeling for determining tracer stability under the physicochemical conditions to be expected in the site. The final selection includes ⁶Li, ⁸⁷Rb, D (as D₂O) and I (as I⁻). Hydrogeochemical modeling confirmed the stability of all the tracers selected. Batch sorption experiments showed that no sorption in the rock occurred in the case of ⁶Li, D and I (conservative tracers), whereas ⁸⁷Rb was 100% sorbed. However, ⁸⁷Rb was chosen because of its analogy with Cs, a relevant radionuclide commonly present in the nuclear spent fuel.Diffusion experiments have been carried out at laboratory scale with Opalinus Clay samples to provide diffusion parameters for modeling purposes. Effective diffusion coefficients, perpendicular and parallel to the bedding planes of the rock, respectively, were (1.68± 0.42)×10⁻¹¹ and (4.02± 0.30)×10⁻¹¹ m²/s for tritium, and (2.70± 0.27)×10⁻¹² and (1.38± 0.49)×10⁻¹¹ m²/s for iodide. Additional through-diffusion experiments (parallel to the bedding) were performed with the nonsorbing tracer ³⁶Cl⁻, in order to check the results obtained for iodide. The effective diffusion coefficient measured for chloride ions was (1.18± 0.27)×10⁻¹¹ m²/s, which is practically equal to the value obtained for iodide.Preliminary diffusion calculations have been carried out using two transport codes: GIMRT and CORE^2D, with conservative and nonconservative tracers, using effective diffusion coefficients (D_e) obtained experimentally in the laboratory (through-diffusion experiments) or selected from the literature. The diffusion profiles obtained from the calculations showed slight variations, which were consistent with the different modeling approaches employed. The predictive modeling results have been used to determine the initial tracer concentration that should be added to the circuit to assure well-defined profiles at the end of the experiment.This long-term in situ diffusion experiment will also provide useful data for the interpretation of previous diffusion experiments performed at the Mont Terri URL.     

Estimation of deuterium recoveries from each component of water-isotope mixture in continuous-flow thermal diffusion columns

The present study deals with the estimation of deuterium recovery from the separation of water-isotope mixture (H₂O-HDO-D₂O) by continuous-flow thermal diffusion. First, the equations for predicting the degrees of separation for each component in H₂O-HDO-D₂O system were derived. The recovery of deuterium (D) was then estimated from the degrees of separation of HDO and D₂O. The most important assumption in this work was that the concentrations of each component were at local equilibrium within the thermal diffusion column, i.e. H₂O + D₂O ? 2HDO. It was found that D₂O preferably transfers to the bottom end of the column, while HDO does the same for dilute feed concentration, but then transfers to the top of the column when the feed concentration of D₂O, C_3F, increases to 0.3. The maximum total recovery of deuterium from HDO and D₂O occurs at C_3F = 0.25.     

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.     

IR and NMR characterisation of extraction products of reductively deuteromethylated coals

Products of reductive methylation and deuteromethylation of two Polish coals of different rank performed in the potassium/liquid ammonia system were subjected to extraction by dichloromethane. Spectral analysis of the extracts was made. A comparison of ¹H and ²H NMR spectra indicated that the cleavage of C–C bonds in methylene bridges is of substantial importance for the fragmentation of the coal structure taking place under the effect of potassium in liquid ammonia. This finding was confirmed by results of IR analysis.     

Oxidative Stability and Volatile Formations in Linoleic Acid-D<Subscript>2</Subscript>O Models in the Presence of Deuteron or Electron Donors

Effects of deuteron (D⁺) and electron donors on the oxidative stability in linoleic acid–water model systems were evaluated by analyzing headspace oxygen content and headspace volatiles. Acetic acid‐d and tetrakis(dimethylamino)ethylene (TDAE) were selected as a deuteron and an electron donor, respectively. Samples containing acetic acid‐d had significantly lower headspace oxygen content than controls while those containing TDAE had significantly higher headspace oxygen content (p < 0.05). Combination of acetic acid‐d and TDAE accelerated the consumption of headspace oxygen. Volatiles including t‐2‐heptenal, 2‐octenal, or 2,4‐octadienal had higher mass to charge ratio (m/z) of (molecular weight +1)/molecular weight in samples with deuterium oxide than in samples with deuterium free water. However, no significant difference was observed in the m/z ratio of (molecular weight +1)/molecular weight of those volatiles among samples with or without deuteron or electron donors. Also, lipid hydroperoxides with deuterium, were not found in samples containing deuterium oxide and acetic acid‐d. Therefore, added acetic acid‐d may not be involved on the formation of lipid hydroperoxides and volatiles directly.     

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.     

ANALYSIS OF DEUTERIUM CONTENT IN HYDROCARBONS VIA CAPILLARY CHROMATOGRAPHY

The deuterium content of hydrocarbons can be successfully determined using peak shape analysis of high resolution capillary chromatograms.     

Feasibility study of an intense D–T fusion source: “The New Sorgentina”

The international community agrees on the importance to build a large facility devoted to test and validate materials to be used in harsh neutron environments. Such a facility, proposed by ENEA, reconsiders a previous study known as “Sorgentina” but takes into account new technological development so far attained. The “New Sorgentina” Fusion Source (NSFS) project is based upon an intense D–T 14 MeV neutron source achievable with T and D ion beams impinging on 2 m radius rotating targets. NSFS produces about 1 × 10¹³ n cm⁻² s⁻¹ over about 50 cm³. Larger volumes of lower neutron flux will be available (e.g. for TBM experiments) as well as collimated channels to study some features of the ITER neutron camera. The NSFS facility will overcome problems related to the ion source and accelerating system, by means of an upgraded version of the JET–PINI ion beams. NSFS has to be intended as an European facility that may be realized in a few years, once provided a preliminary technological program devoted to the operation of the ion source in continuous mode, target heat loading/removal, target and tritium handling, inventory as well as site licensing. In this contribution, the main characteristics of NSFS project will be presented.     

Deuterium NMR study of the MP-2269: albumin interaction — a step forward to the dynamics of non-covalent binding

MP-2269, the Gd(III) complex of 4-pcntylbicyclo[2.2.2] octane-l-carboxyl-di-L-aspartyl-lysinc-derived-DTPA, is a small Gd-agent that binds non-covalently to scrum albumin in vivo to assume the enhanced relaxivities associated with macromolecular agents, (due in part to increased rotational correlation time, τ_R). To further explore the fundamental parameters that govern the dynamics of water proton relaxation enhancement by this prototypical albumin-binding agent, the rotational correlation time (τ_R) for the deuterated La(III) analog of MP-2269 has been independently measured in the presence and absence of 4% albumin using²H-NMR approaches. The diamagnetic La(III) analog of MP-2269 was deuterated at the α-position of the carbonyl groups.²H-NMR studies were conducted at 7.05T (46 MHz) and 310°K on a Bruker NMR spectrometer. Spectral deconvolution permitted calculation of transverse relaxation rates, 1/T₂, from the NMR linewidths and subsequently, τ_R. The results yielded a τ_R of the albumin bound complex of ∼ 8 ns. This value is intermediate between those earlier estimated by¹⁷O-NMR (∼ 1 ns) and¹H-NMRD (∼ 20–50 ns) and significantly shorter than that of albumin. The²H-NMR study results also indicate that the exchange between free and albumin-bound forms of the La(III) analog is slow (exchange lifetimes > 1 ms). This slow exchange does not affect the water residence lifetimes (τ_M 140-280 ns).