共查询到20条相似文献,搜索用时 31 毫秒
1.
Masanori Suzuki Ken Kurosaki Shinsuke Yamanaka Toshihiro Tanaka Masayoshi Uno Yukihiro Murakami 《Journal of Nuclear Science and Technology》2018,55(8):885-899
In case of severe nuclear accidents involving melt down of nuclear fuels at high temperatures, it is of considerable importance to accurately evaluate the highly-volatizing behavior of fission products (FPs) over multicomponent debris. Particularly, cesium (Cs)- and iodine (I)- bearing chemical species are regarded as notable FPs. In the present work, the authors have generated original thermodynamic databases for the system U–Zr–Ce–Cs–Fe–B–C–I–O–H featuring Cs- as well as I-bearing subsystems, which are contained in oxide, iodide, and metal (including borides and carbides) sub-databases. It has been confirmed that the phase diagrams calculated by the present set of the databases reproduce the corresponding literature data well in various kinds of subsystems of the above multicomponent system. The present set of databases has subsequently been applied to simulate phase equilibria and volatizing behavior of Cs- and I-including species, respectively, in multicomponent debris under specific temperature and atmospheric conditions corresponding to severe nuclear accidents. 相似文献
2.
Paul David W. Bottomley Mairead Murray-Farthing Dario Manara Thierry Wiss Bert Cremer Cos Boshoven 《Journal of Nuclear Science and Technology》2015,52(10):1217-1225
During a severe nuclear accident, the UO2 fuel rods, Zircaloy cladding, guide tubes, absorber and steel structural components inside the reactor pressure vessel overheat and a series of interactions between these elements and the steam atmosphere occur. These produce more heat in addition to the decay heat and result in a liquid corium of oxidic and metallic phases depending on the exact conditions and processes. A major systems resulting from this is the U–Zr–Fe–O system. High-temperature data for this system is important in order to be able to model these interactions. The Joint Research Centre, Institute for Transuranium Elements (JRC-ITU) has been examining the melting ranges for this system over the whole FeO range by means of a specialized laser flash technique that achieves very high temperatures and avoids crucible contamination. The melted zones were examined for their structure, composition and for estimation of the liquidus and solidus temperatures. The results showed that with FeO contents of over 20mol% there was a very large melting range that would permit long liquid cooling times and extend the relocation of fuel material within the reactor pressure vessel. Based on these results, the main phase regimes expected under severe accident conditions could be identified. 相似文献
3.
Kaushik Ghoshal T.R.G. Kutty Sudhir Mishra Arun Kumar 《Journal of Nuclear Materials》2013,432(1-3):20-22
Creep behavior of U–7%Zr, U–5%Zr–2%Nb, U–3.5%Zr–3.5%Nb, U–2%Zr–5%Nb, U–7%Nb alloys (composition in wt.%) was investigated by the impression creep technique at 630 and 700 °C at a stress of 22.2 MPa. Creep rate was found to be two orders lower in the binary U–7%Nb than the U–7%Zr alloy. In ternary U–Nb–Zr alloys, the creep rate was found decreasing drastically with the increase in Nb content. 相似文献
4.
When the thermal diffusivity, χ, of a thin film on a substrate is measured by means of the mirage method, the photothermal deflection of the probe beam is determined by the heat radiation field contributed by the film and the substrate, heated by the pump beam. A two-dimensional algorithm is here presented in order to deduce the measure of the diffusivities of the film and the substrate in one set of mirage detection from the experimental data. 相似文献
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6.
S. Nagata M. Sasase K. Takahiro B. Tsuchiya A. Inouye S. Yamamoto T. Shikama 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1514-1517
The effect of the ion implantation on the phase transformation was studied for glassy and crystalline Zr55Al10Ni5Cu30 alloys, using Au+ ions with 500 keV. For the glassy metal surface, nano-crystalline precipitates were effectively formed in the amorphous matrix by 500 keV Au ion irradiation at a fluence of the about 1016 cm?2. On the contrary, the long range ordering in the partly crystalline alloy was lost by the irradiation under the same condition. Moreover, the precipitation during the heat treatment near the crystallizing temperature was effectively suppressed in the ion implanted area. In the irradiated surface, the XPS valence band structure was drastically changed, while shifts of the binding energy were found in the core level electrons of Au 4f and Cu 2p, indicating a strong interaction between the implanted Au atoms and constituent atoms of the Zr-based alloy. 相似文献
7.
Jong-Hwan Kim Jung Won Lee Ki-Hwan Kim Jeong-Yong Park 《Journal of Nuclear Science and Technology》2017,54(6):648-654
U–Zr fuel slugs containing rare-earth elements can be difficult to cast because of the high reactivity of rare-earth elements. In this study, U–Zr and U–Zr–RE (RE: a rare-earth alloy comprising 53% Nd, 25% Ce, 16% Pr, and 6% La by weight) fuel slugs were prepared by injection casting, and their characteristics were evaluated. The as-cast fuel slugs were fabricated to the full length of the mold, and they showed no thin sections or cracks. Compared to the theoretical density, the measured density of the U–Zr and U–Zr–RE fuel slug was lower and higher, respectively. Chemical analysis revealed that the Zr and RE compositions in the U–10Zr and U–10Zr–3RE fuel slugs matched the target composition within 1.0 wt%. However, the RE composition in the U–10Zr–7RE fuel slug differed from the target composition by over 4 wt%. The melting crucible was further deteriorated and the casting yield was lower for the casting of a high rare-earth bearing fuel slug. 相似文献
8.
Luca Lutterotti 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(3-4):334-340
A global approach has been developed to analyze complex thin film structures by X-ray diffraction. The method is based on the fitting of multiple data, diffraction pattern and/or images, collected at different orientation of the sample to obtain all the information needed. It requires the knowledge of the crystal structure for the phases present in the film, or if the amount/film thickness is sufficient, the crystal structure can be also determined or refined. Reflectivity patterns can be added to the global refinement to improve the accuracy of the thickness determination and when coupled with total X-ray fluorescence can give the in depth chemical concentrations. In addition, it constraints the solution for the quantitative phase analysis obtained from the diffraction patterns. The principles of the analysis with the main methods will be presented from the theoretical point of view. These cover the models from crystal structure to texture, residual strain/stresses, crystallite sizes and microstrains. To make the method more effective, some specific models have been developed in the past few years.Then some experimental/analysis examples will be given to enlighten how the method works and what kind of information can be obtained. Not every model suits every analysis or kind of thin film and the examples will cover different cases from multiple phases to strong texture, epitaxial thin films or multilayers. 相似文献
9.
N. Das Pranesh Sengupta S. Roychowdhury G. Sharma P.S. Gawde A. Arya V. Kain U.D. Kulkarni J.K. Chakravartty G.K. Dey 《Journal of Nuclear Materials》2012,420(1-3):559-574
Alloy melting route is currently being considered for radioactive hulls immobilization. Towards this, wide range of alloys, belonging to Zirconium–Iron binary and Zirconium–Stainless steel pseudo-binary systems have been prepared through vacuum arc melting route. Detail microstructural characterization and quantitative phase analyses of these alloys along with interaction study between Zirconium and Stainless steel coupons at elevated temperatures identify Zr(Fe,Cr)2, Zr(Fe,Cr), Zr2(Fe,Cr), Zr3(Fe,Ni), Zr3(Fe,Cr), Zr3(Fe,Cr,Ni), β-Zr and α-Zr as the most commonly occurring phases within the system for Zirconium rich bulk compositions. Nano-indentation studies found Zr(Fe,Cr)2 and Zr(Fe,Cr) as extremely hard, Zr3(Fe,Ni) as moderately ductile and β-Zr, Zr2(Fe,Cr) as most ductile ones among the phases present. Steam oxidation studies of the alloys, based on weight gain/loss procedure and microstructural characterization of the mixed oxide layers, suggest that each of the alloys responded to the corrosive environment differently. Fe2O3, NiFe2O4, NiO, monoclinic ZrO2 and tetragonal ZrO2 are found to be most common constituents of the oxide layers developed on the alloys. Integrating the microstructural, mechanical and corrosion properties, ZrFeCrNi3 (Zr: 84.00, Fe: 11.20, Cr: 3.20, Ni: 1.60, in wt.%) is identified as the acceptable base alloy for disposal of radioactive hulls. 相似文献
10.
We have studied the gamma and X-ray radiation compatibility of Ti-based alloys such as Ti–37 Ta–26 Hf–13 Zr-24(wt%) [Alloy 1], Ti–40 Ta–22 Hf–11.7 Zr-26.3(wt%) [Alloy 2], Ti–45 Ta–18.4 Hf–10 Zr-26.6(wt%) [Alloy3], Ti–50 Ta–15 Hf–8 Zr-27(wt%) [Alloy 4], Ti–55 Ta–12 Hf–7 Zr-26(wt%) [Alloy 5], and Ti–60 Ta–10 Hf–5 Zr-25(wt%) [Alloy 6]. Gamma and X-ray radiation compatibility is studied by evaluating the mass attenuation coefficient,mean free path, HVL, TVL effective atomic number,effective electron density, exposure buildup factor, and relative dose. We have compared these parameters for studied alloys with that of arteries. The alloys Ti–55 Ta–12 Hf–7 Zr-26 and Ti–60 Ta–10 Hf–5 Zr-25 have added properties such as gamma/X-ray radiation compatibility,high elastic admissible strain, high mechanical strength,and excellent biocompatibility. Hence, we may suggest that, among Ti–Ta–Hf–Zr alloys, these alloys are best materials for coronary stent applications. 相似文献
11.
C. Sun K.Y. Yu J.H. Lee Y. Liu H. Wang L. Shao S.A. Maloy K.T. Hartwig X. Zhang 《Journal of Nuclear Materials》2012,420(1-3):235-240
The evolutions of microstructure and mechanical properties of Fe–14Cr–16Ni (wt.%) alloy subjected to Helium ion irradiations were investigated. Equal channel angular pressing (ECAP) process was used to significantly reduce the average grain size from 700 μm to 400 nm. At a peak fluence level of 5.5 displacement per atom (dpa), helium bubbles, 0.5–2 nm in diameter, were observed in both coarse-grained (CG) and ultrafine grained (UFG) alloy. The density of He bubbles, dislocation loops, as well as radiation hardening were reduced in the UFG Fe–Cr–Ni alloy comparing to those in its CG counterpart. The results imply that radiation tolerance in bulk metals can be effectively enhanced by refinement of microstructures. 相似文献
12.
We generalize the symmetry transformations for magnetohydrodynamic (MHD) equilibria with isotropic pressure and incompressible flow parallel to the magnetic field introduced by Bogoyavlenskij in the case of the respective Chew–Goldberger–Low (CGL) equilibria with anisotropic pressure. We find that the geometrical symmetry of the field-aligned equilibria can be broken by those transformations only when the magnetic field is purely poloidal. In this situation we derive three-dimensional CGL equilibria from given axisymmetric ones. Also, we examine the generic symmetry transformations for MHD and CGL equilibria with incompressible flow of an arbitrary direction, introduced in a number of papers, and find that they cannot break the geometrical symmetries of the original equilibria, unless the velocity and magnetic field are collinear and purely poloidal. 相似文献
13.
《核技术(英文版)》2017,(12)
The embrittlement of nickel-based structural alloys by fission-produced tellurium(Te) is a major challenge for molten salt reactors(MSR). In this study, the effects of thermal exposure time on tellurium diffusion in a candidate MSR structural alloy(Ni–16 Mo–7 Cr–4 Fe) and the consequent mechanical property degradation of the alloy were investigated through surrogate diffusion experiments at 700 °C. The results show that some tellurium reacted with the alloy to form tellurides on the surface,while some tellurium diffused into the alloy along grain boundaries. Ni_3Te_2 and CrTe were the most stable reaction products at the tested temperature, and the formation of CrTe on the surface induced the Cr depletion at grain boundaries of the alloy. The diffusion depth of Te increased gradually with thermal exposure time, and thediffusion rate kept stable within the test duration of up to3000 h. The Te diffusion in the alloy caused the embrittlement of grain boundaries, inducing crack formation and strength degradation in tensile test at room temperature. 相似文献
14.
Z.S. Li X.J. Liu M.Z. Wen C.P. Wang A.T. Tang F.S. Pan 《Journal of Nuclear Materials》2010,396(2-3):170-175
The phase diagrams of the Al–Th and Th–Zn systems have been evaluated by using the Calculation of Phase Diagrams (CALPHAD) method with the experimental data including the phase equilibria and thermodynamic properties. The Gibbs free energies of the liquid, bcc and hcp phases were described by the subregular solution model with the Redlich–Kister equation, and those of the stoichiometric compounds of the Th2Al, Th3Al2, ThAl, Th2Al3, ThAl2, ThAl3, Th2Al7, Th2Zn, ThZn2, ThZn4 and Th2Zn17 were described by the two-sublattice model. The calculated phase equilibria and thermodynamic properties are in good agreement with the experimental data. 相似文献
15.
Predrag S. Krstic Jean Paul Allain Alain Allouche Jacek Jakowski Jonny Dadras Chase N. Taylor Zhangcan Yang Keiji Morokuma Satoshi Maeda 《Fusion Engineering and Design》2012,87(10):1732-1736
Chemistry as well as sputtering and reflection dynamics of lithiated carbon material, bombarded by slow hydrogen atoms are studied. We present a realistic method for computational simulation of the dynamics of the polar Li–C–O–H material dynamics. It is based on an approximate, semi-empirical quantum mechanics of electrons and classical mechanics of nuclei. Results are validated qualitatively by comparison with experiments and with a first principle DFT computations. In particular, we explain observed details of the hydrogen bonding chemistry in lithiated carbon, showing that incoming hydrogen interacts preferably with Li-C rather than C structures. 相似文献
16.
《Journal of Nuclear Materials》2001,288(2-3):100-129
The thermodynamic modelling of the carbon–uranium (C–U) and boron–uranium (B–U) binary systems is being performed in the framework of the development of a thermodynamic database for nuclear materials, for increasing the basic knowledge of key phenomena which may occur in the event of a severe accident in a nuclear power plant. Applications are foreseen in the nuclear safety field to the physico-chemical interaction modelling, on the one hand the in-vessel core degradation producing the corium (fuel, zircaloy, steel, control rods) and on the other hand the ex-vessel molten corium–concrete interaction (MCCI). The key O–U–Zr ternary system, previously modelled, allows us to describe the first interaction of the fuel with zircaloy cladding. Then, the three binary systems Fe–U, Cr–U and Ni–U were modelled as a preliminary work for modelling the O–U–Zr–Fe–Cr–Ni multicomponent system, allowing us to introduce the steel components in the corium. In the existing database (TDBCR, thermodynamic data base for corium), Ag and In were introduced for modelling AIC (silver–indium–cadmium) control rods which are used in French pressurized water reactors (PWR). Elsewhere, B4C is also used for control rods. That is why it was agreed to extend in the next years the database with two new components, B and C. Such a work needs the thermodynamic modelling of all the binary and pseudo-binary sub-systems resulting from the combination of B, B2O3 and C with the major components of TDBCR, O–U–Zr–Fe–Cr–Ni–Ag–In–Ba–La–Ru–Sr–Al–Ca–Mg–Si + Ar–H. The critical assessment of the very numerous experimental information available for the C–U and B–U binary systems was performed by using a classical optimization procedure and the Scientific Group Thermodata Europe (SGTE). New optimized Gibbs energy parameters are given, and comparisons between calculated and experimental equilibrium phase diagrams or thermodynamic properties are presented. The self-consistency obtained is quite satisfactory. 相似文献
17.
Electrorefining of nickel in LiCl–KCl melt was investigated using electrochemical techniques. Nickel products after electrorefining were characterized by X-ray diffraction, X-ray fluorescence, and scanning electron microscopy. Both cyclic voltammetry and square wave voltammetry results suggested that Ni~(2+) was directly reduced to Ni metal in Li Cl–KCl. Based on a preliminary study on the electrochemical behavior of nickel and chromium, electrorefining was carried out under constant potential, whereupon deposits were formed on the cathode.The purity of nickel increased from 72.62% in the original alloy to 99.83% in cathodic deposits, as determined by inductively coupled plasma atomic emission spectroscopy analysis. Almost all the nickel in the alloy could be recovered during the electrochemical process with [ 90%current efficiency. A lower concentration of Ni Cl_2 in Li Cl–KCl was found to be favorable for nickel electrorefining, as increased Ni Cl_2 concentration caused severe corrosion of the nickel anode at the gas–liquid interface due to the accumulation of Cl_2 gas. 相似文献
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19.
Xiaoxing Liu Yuki Aramaki Liancheng Guo Koji Morita 《Journal of Nuclear Science and Technology》2013,50(12):1480-1489
We want to simulate, based on particle methods, the dynamic behavior of multi-phase flows in a gas–solid–liquid mixture system. With the governing equations discretized within the finite volume particle method, the effects of contact and collision between solid particles were modeled by the distinct element method. Applicability of the viscosity model and an empirical drag force model were confirmed for the hydrodynamic interactions between solid particles and fluid. Simulations were performed of a single bubble rising in a tank of stagnant solid particle–liquid. The results for the dynamic behavior indicate that the present computational framework of particle-based simulation method may be useful for numerical simulations of multi-phase flow behavior in a solid particle–fluid mixture system. 相似文献