[en] Uranium is a crucial strategic resource as well as the most important fuel for nuclear power generation. The stable and reliable supply of uranium is of great significance to ensure the development of nuclear power. According to the latest edition of the Red Book and some other relevant available information, current update data and general situation on uranium resources, production and demand are presented, along with some detailed information on the changes of resources, recent developments of exploration and production activities, production cost, and comprehensive assessment of demand and supply. (authors)

[en] Electron energy distributions of direct-current argon discharges at low pressure were calculated by numerically solving the homogeneous Boltzmann equation. The calculations covered the whole range of low electron densities to sufficiently high electron densities. Typical values of the ratios of the electric field to the gas density in this work are in the ranges of 10^-16 < E/N < 10^-15 Vcm². The influence of electron-electron collisions and the electric field on the electron energy distribution function was studied

[en] SiC nanowires were in-situ synthesised onto SiC coated carbon/carbon (C/C) composites to construct SiC nanowire reinforced magnesium aluminosilicate (SiCnw/MAS) nanocomposites for strengthening and toughening carbon/carbon-lithium aluminosilicate (C/C-LAS) joints. Polymer impregnation pyrolysis (PIP) technique was applied to prepare high purity SiC nanowires. A layer of SiCnw/MAS nanocomposites with ~ 30 µm was achieved between SiC ceramic coating and MAS interlayer via hot-pressing sintering. As a result of debonding, pulling out and deflecting crack mechanisms of the nanowires, fracture pattern was changed from brittle fracture to pseudo-plastic fracture, accompanied by significantly increased shear strength and enhanced work of fracture. The introduced SiC nanowires could dissipate the energy enquired for crack propagation by arresting and deflecting cracks and contribute to the improved mechanical performance. Shear strength and work of fracture of the PIP SiC nanowires reinforced C/C-LAS joints were improved respectively by 94% and 61%, ascribed to the formation of SiCnw/MAS nanocomposites.

[en] Using first-principles calculations, we investigate the stabilities of He and He_n-vacancy (He_nV) clusters in α-Fe and W. Vacancy formation energies are 2.08 eV in α-Fe and 3.11 eV in W, respectively. Single He in both α-Fe and W prefers to occupy the tetrahedral interstitial site. We recalculated the He solution energy considering the effect of zero-point energy (ZPE). The ZPEs of He in α-Fe and W at the tetrahedral (octahedral) interstitial site are 0.072 eV (0.031 eV) and 0.078 eV (0.034 eV), respectively. The trapping energies of single He at vacancy in α-Fe and W are −2.39 eV and −4.55 eV, respectively. By sequentially adding He into vacancy, a monovacancy trap up to 10 He atoms distributing in the vacancy vicinity. Based on the above results combined with statistical model, we evaluate the concentrations of all relevant He_nV clusters as a function of He chemical potential. The critical He_nV concentration is found to be ∼10⁻⁴⁰ (atomic) at the critical temperature T = 600 K in α-Fe and T = 1600 K in W, respectively. Beyond the critical He_nV concentrations, considerable He_nV aggregate to form He_nV_m clusters. By further growing of He_nV_m, the He_nV_m clusters grow bigger resulting in the larger He bubble formation

[en] Long-term management of China's coal overcapacity depends on the targeted policy guidance on industry production capacity expansion in the overcapacity formation process. In this study, coal enterprise and local government are treated as game participants, and a three-stage dynamic game model has been developed to depict the boosting effect of the game behavior of coal enterprise's and local government's capacity investments in different markets of supply and demand. The results are shown in the following: (1) local government has been the 'behind-the-scenes' operator of over-investment and redundant construction, and its excessive interventions in coal industry investment have been the primary cause of overcapacity formation; (2) when the market is in short supply, coal enterprise's optimal behavior is to continuously increase the rate of investment growth until it reaches the threshold to obtain the maximum excess profits, ultimately leading to overinvestment in the industry; and (3) the key factors affecting the game abilities of coal enterprise and local government are the market's self-regulation and the central government's supervision intensity. Although the Chinese government, a highly vertically oriented bureaucratic structure, is implementing a mandatory de-capacity policy to alleviate the intensity of excessive coal capacity, it is not a long-term regularization on the supply-side reform. - Highlights: • The formation of China's coal overcapacity is studied from capacity investors. • A three-stage game is developed to depict the boosting effect of coal overcapacity. • Local government has been the 'behind-the-scenes' operators of coal overcapacity. • Coal enterprise's optimal strategy is reaching an investment-max with undersupply. • Chinese government should rely more on market mechanisms instead of intervention.

[en] The properties and reactivity of Si-doped hexagonal boron nitride (h-BN) sheets were studied using density functional theory (DFT) methods. We find that Si impurity is more likely to substitute the boron site (Si_B) due to the low formation energy. Si-doping severely deforms h-BN sheet, resulting in the local curvature changes of h-BN sheet. Moreover, Si-doping introduces two spin localized states within the band gap of h-BN sheet, thus rendering the two doped systems exhibit acceptor properties. The band gap of h-BN sheet is reduced from ∼4.70 eV to 1.24 (for Si_B) and 0.84 eV (for Si_N), respectively. In addition, Si-doped one exhibits higher activity than pristine one, endowing them wider application potential. - Highlights: • Si-doping severely deforms the geometrical structures of the h-BN sheet. • The band gap of the h-BN sheet is greatly decreased after Si-doping. • The reactivity of the h-BN sheet to some common gas molecules is enhanced in various ways

[en] The reliability of reactor protection system is very important to the safety of NPP. With the raise of digital control system, the reactor protection system has also been transferred from analog technology to digital technology. Because of the specificity of software, V&V technology used for software verification comes along. The mainstream standard of V&V technology - IEEE 1012 with its nice operability, has been used rather widely in the industry. IEEE 1012-2004, which still focuses on software level, is the most widely used version until now. From the IEEE 1012-2012, the concepts and requirements of V&V focusing on system and hardware are proposed. Although IEEE 1012-2012 has expansion the content of V&V to system and hardware level, a mature and operable method is lack, and this version is not endorsed by NRC, which results that the application according to this version of standard is very less in NPP V&V. To solve this problem, this paper pays attention to the discussion and research on the method and the operability of hardware V&V, which proposes a set of practical hardware V&V method for NPP reactor protection system (RPS). This paper will introduce a set of hardware V&V method for reactor protection system. This method provides a useful reference for people who do the allied work in the industry. (author)

[en] Novel two-dimensional materials with a layered structure are of special interest for a variety of promising applications. In current research, the nanostructured graphene oxide-Fe₂O₃ composite (GO-Fe₂O₃) was firstly obtained via a carefully elaborated approach of vacuum freeze-drying. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) images revealed that α-Fe₂O₃ nanoparticles loaded well on the surfaces of graphene. A series of characterization were performed to further elucidate the as-obtained nanomaterial's physicochemical properties. These results suggested the current route could be further extended to obtain the other kinds of two-dimensional materials based composites. For the sake of extending the potential application of herein achieved graphene composites, its cytotoxicity assessment on HeLa cells was systematically investigated. CCK-8 assay in HeLa cells treated by GO-Fe₂O₃ showed dose- (1–100 μg/ml) and time- (24–48 h) dependent cytotoxicity, which was comparable to that of GO. The excess generation of intracellular reactive oxygen species (ROS) induced by these nanomaterials was responsible for the cytotoxicity. TEM analysis vividly illustrated GO-Fe₂O₃ internalized by HeLa cells in endomembrane compartments such as lysosomes, and degraded through autophagic pathway. The detrimental biological consequence accompanied by cell internalization was limited. Based on the above results, it expected to render useful information for the development of new and popular strategies to design graphene-based composites, as well as deep insights into the mechanism of graphene-based composites cytotoxicity for further potential application.

[en] This paper establishes a strategy for chemical deposition of functionalized nanoparticles onto solid substrates in a layer-by-layer process based on self-limiting surface chemical reactions leading to complete monolayer formation within the multilayer system without any additional intermediate layers — nanoparticle layer deposition (NPLD). This approach is fundamentally different from previously established traditional layer-by-layer deposition techniques and is conceptually more similar to well-known atomic and molecular layer deposition processes. The NPLD approach uses efficient chemical functionalization of the solid substrate material and complementary functionalization of nanoparticles to produce a nearly 100% coverage of these nanoparticles with the use of “click chemistry”. Following this initial deposition, a second complete monolayer of nanoparticles is deposited using a copper-catalyzed “click reaction” with the azide-terminated silica nanoparticles of a different size. This layer-by-layer growth is demonstrated to produce stable covalently-bound multilayers of nearly perfect structure over macroscopic solid substrates. The formation of stable covalent bonds is confirmed spectroscopically and the stability of the multilayers produced is tested by sonication in a variety of common solvents. The 1-, 2- and 3-layer structures are interrogated by electron microscopy and atomic force microscopy and the thickness of the multilayers formed is fully consistent with that expected for highly efficient monolayer formation with each cycle of growth. This approach can be extended to include a variety of materials deposited in a predesigned sequence on different substrates with a highly conformal filling. - Highlights: • We investigate the formation of high-coverage monolayers of nanoparticles. • We use “click chemistry” to form these monolayers. • We form multiple layers based on the same strategy. • We confirm the formation of covalent bonds spectroscopically for up to 3 layers. • We confirm that chemical attachment, not self-assembly, drives the process.

[en] Using first-principles simulation, we have performed the study on the mechanical behaviors of body-centered-cubic W_1_-_xCr(Ti)_x binary alloys (0 < x < 0.1) as a function of Cr (Ti) composition. The lattice constants, elastic constants, Young's moduli, and shear moduli are investigated for single crystal W_1_-_xCr(Ti)_x binary alloys. Cr and Ti can, respectively, shrink and enlarge the lattice structure of W due to their different atomic radius. The influence of alloying on C_1_1 is larger than that on C_1_2 and C_4_4 with the increase of Cr/Ti concentration. For polycrystalline W-based alloys, bulk modulus B, Young's modulus E, shear modulus G, Poisson's ratio v, Zener anisotropy factor A, Debye temperature Θ_D, and B/G have been also calculated. All these quantities display regular change trend with increasing Cr/Ti concentration. Cr and Ti exhibit the opposite alloying effect on the thermodynamic stability of alloy. W_1_-_xCr(Ti)_x is energetically unstable (stable) with random Cr (Ti) concentration at any temperature considered in the current study. This result well approves the experiment on that the alloying element Ti can enhance the mechanical properties at ambient and intermediate temperatures.