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1.
Effect of the presence of In and Sn in the oxygen chemistry in molten 44.5% lead-55.5% bismuth alloy
S. Colominas 《Journal of Nuclear Materials》2008,376(3):375-380
The oxygen activity and its control is a key parameter in the use of molten lead-bismuth eutectic LBE in accelerator-driven systems (ADS) reactors. The presence of pollutants in the molten alloy, such as metallic impurities dissolved from the structural material or from other sources, can modify the oxygen chemistry in the molten alloy. For this reason, the oxygen activity in molten LBE has been studied under the presence of In and Sn as a metallic impurities. All the experiments were performed with a shift of the covering gas from a reductive environment (Ar + 10% H2) to air (20% O2). These covering gas conditions were used to enable measurement of the electrochemical potential of the sensor in a low oxygen environment and under oxygen saturation conditions of the molten alloy (Me/LBE). All of the tests were performed at 500 °C and in stagnant conditions in an autoclave. 相似文献
2.
Yuji Kurata 《Journal of Nuclear Materials》2011,415(3):254-259
The static corrosion tests in lead-bismuth eutectic (LBE) were conducted from 450 °C to 600 °C to understand corrosion behavior and develop corrosion resistant materials for heavy liquid metal systems. While increase of Cr content in steels enhances corrosion resistance in LBE, the effect approaches a constant value above 12 wt% of Cr. Corrosion depth in LBE increases with increasing temperature and corrosion attack becomes severe above 550 °C even under the condition of high oxygen concentration. Nickel dissolution and Pb-Bi penetration occur in 316SS and JPCA above 550 °C under the condition of high oxygen concentration. When oxygen concentration decreases below the level of Fe oxide formation, corrosion attack on these steels also becomes violent due to dissolution of various elements and grain boundary corrosion. Whereas additions of 1.5 wt% Si to T91 and 2.5 wt% Si to 316SS improve corrosion resistance, the effect is insufficient taking fluctuation of oxygen concentration in LBE into consideration. Furthermore, addition of 1.5 wt% Si to T91 causes rise in DBTT. A new coating method using Al, Ti and Fe powders produces corrosion resistant coating layers on 316SS. The coating layers containing 6-8 wt% Al exhibit good corrosion resistance at 550 °C for 3000 h in LBE containing 10−6-10−4 wt% of oxygen. 相似文献
3.
N. Srinivasa Rao A.P. Pathak P.K. Kulriya F. Singh J.C. Pivin 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,264(2):249-253
Germanium nanoparticles embedded in SiO2 matrix were prepared by atom beam sputtering on a p-type Si substrate. The as-deposited films were annealed at temperatures of 973 and 1073 K under Ar + H2 atmosphere. The as-deposited and annealed films were characterized by Raman, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR). Rutherford backscattering spectrometry was used to quantify the concentration of Ge in the SiO2 matrix of the composite thin films. The formation of Ge nanoparticles were observed from the enhanced intensity of the Ge mode in the Raman spectra as a function of annealing, the appearance of Ge(3 1 1) peaks in the X-ray diffraction data and the Ge vibrational mode in the FTIR spectra. We have irradiated the films using 100 MeV Au8+ ions with a fluence of 1 × 1013 ions/cm2 and subsequently studied them by Raman and FTIR. The results are compared with the ones obtained by annealing. 相似文献
4.
Corrosion tests of several US martensitic and austenitic steels were performed in a forced circulation lead-bismuth eutectic non-isothermal loop at the Institute of Physics and Power Engineering (IPPE), Russia. Tube and rod specimens of austenitic steels 316/316L, D-9, and martensitic steels HT-9, T-410 were inserted in the loop. Experiments were carried out simultaneously at 460 °C and 550 °C for 1000, 2000 and 3000 h. The flow velocity at the test sections was 1.9 m/s and the oxygen concentration in LBE was in the range of 0.03-0.05 wppm. The results showed that at 460 °C, all the test steels have satisfactory corrosion resistance: a thin protective oxide layer formed on the steel surfaces and no observable dissolution of steel components occurred. At 550 °C, rod specimens suffered rather severe local liquid metal corrosion and slot corrosion; while tube specimens were subject to oxidation and formed double-layer oxide films that can be roughly described as a porous Fe3O4 outer layer over a chrome-rich spinel inner layer. Neglecting the mass transfer corrosion effects by the flowing LBE, calculations based on Wagner’s theory reproduce the experimental results on the oxide thickness, indicating that the oxide growth mechanism of steels in LBE is similar to that of steels in air/steam, with slight modification by dissolution and oxide dissociation at the liquid metal interface. 相似文献
5.
The corrosion behaviours of austenitic steel AISI 316L and martensitic steel T91 were investigated in flowing lead-bismuth eutectic (LBE) at 400 °C. The tests were performed in the LECOR and CHEOPE III loops, which stood for the low oxygen concentration and high oxygen concentration in LBE, respectively. The results obtained shows that steels were affected by dissolution at the condition of low oxygen concentration (C[O2] = 10−8-10−10 wt%) and were oxidized at the condition of high oxygen concentration (C[O2] = 10−5-10−6 wt%). The oxide layers detected are able to protect the steels from dissolution in LBE. Under the test condition adopted, the austenitic steel behaved more resistant to corrosion induced by LBE than the martensitic steel. 相似文献
6.
Corrosion tests were performed in oxygen-saturated liquid Pb-Bi at 450 °C and 550 °C in a pot for 3000 h for Al-surface-treated steels containing various levels of Cr contents. The Al surface treatments were achieved using a gas diffusion method and a melt dipping method. Al2O3, FeAl2 and AlCr2 produced by the gas diffusion method exhibited corrosion resistance to liquid Pb-Bi, while the surface layer produced by the melt dipping method suffered a severe corrosion attack. Fe4Al13 and Fe2Al5 produced by the melt dipping method disappeared during the corrosion test at 550 °C and only FeAl remained. 相似文献
7.
Leaching experiments were performed on UO2 pellets doped with alpha-emitters (238/239Pu) and on spent fuel, in the presence of an external gamma irradiation source (A60Co = 260 Ci, Gy h−1). The effects of α, β, γ radiation, the fuel chemistry and the nature of the cover gas (aerated or Ar + 4%H2) on water radiolysis and on oxidizing dissolution of the UO2 matrix are quantified and discussed. For the doped UO2 pellets, the nature of the cover gas clearly has a major role in the effect of gamma radiolysis. The uranium dissolution rate in an aerated medium is 83 mg m−2 d−1 compared with only 6 mg m−2 d−1 in Ar + 4%H2. The rate drop is accompanied by a reduction of about four orders of magnitude in the hydrogen peroxide concentrations in the homogeneous solution. The uranium dissolution rates also underestimate the matrix alteration rate because of major precipitation phenomena at the UO2 pellet surface. The presence of studtite in particular was demonstrated in aerated media; this is consistent with the measured H2O2 concentrations (1.2 × 10−4 mol L−1). For spent fuel, the presence of fission products (Cs and Sr), matrix alteration tracers, allowed us to determine the alteration rates under external gamma irradiation. The fission product release rates were higher by a factor of 5-10 than those of the actinides (80-90% of the actinides precipitated on the surface of the fragments) and also depended to a large extent on the nature of the cover gas. No significant effect of the fuel chemistry compared with UO2 was observed on uranium dissolution and H2O2 production in the presence of the 60Co source in aerated conditions. Conversely, in Ar + 4%H2 the fuel self-irradiation field cannot be disregarded since the H2O2 concentrations drop by only three orders of magnitude compared with UO2. 相似文献
8.
Mixed uranium-plutonium monocarbide was obtained by carbothermic reduction of mixture of UO2, PuO2 and C at around 1500 °C under vacuum or argon for 4 h followed by sintering at around 1650 °C under mixture of Ar + 8%H2 for 10 h. Moreover, PuO2 was synthesized by oxalic precipitation followed by calcination at around 700 °C (PUREX process). This work deals with a process simplification, i.e. fabrication of carbide by calcination of actinide oxalate, precipitated in presence of carbon, at 1600 °C for 13 h under argon. In this preliminary study, neodymium was used as a surrogate of actinides. No carbon influence was noticed during calcination of neodymium oxalate into oxide. Carbon content was the same before and after calcination making possible conversion to carbide directly from mixture of neodymium oxalate and C. 相似文献
9.
Ambati Pulla Rao 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(8):1517-1521
Titanium-nickel thin films have been deposited on float glass substrates by ion beam sputtering in 100% pure argon atmosphere. Sputtering is predominant at energy region of incident ions, 1000 eV to 100 keV. The as-deposited films were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). In this paper we attempted to study the surface morphology and elemental composition through AFM and XPS, respectively. Core level as well as valence band spectra of ion-beam sputtered Ti-Ni thin films at various Ar gas rates (5, 7 and 12 sccm) show that the thin film deposited at 3 sccm possess two distinct peaks at binding energies 458.55 eV and 464.36 eV mainly due to TiO2. Upon increasing Ar rate oxidation of Ti-Ni is reduced and the Ti-2p peaks begin approaching those of pure elemental Ti. Here Ti-2p peaks are observed at binding energy positions of 454.7 eV and 460.5 eV. AFM results show that the average grain size and roughness decrease, upon increasing Ar gas rate, from 2.90 μm to 0.096 μm and from 16.285 nm to 1.169 nm, respectively. 相似文献
10.
José Luis Montes Juan Luis François Juan José Ortiz Cecilia Martín-del-Campo Raúl Perusquía 《Annals of Nuclear Energy》2009
This paper presents the training of an artificial neural network (ANN) to accurately predict, in very short time, a physical parameter used in nuclear fuel reactor optimization: the local power peaking factor (LPPF) in a typical boiling water reactor (BWR) fuel lattice. The ANN training patterns are distribution of fissile and burnable poison materials in the fuel lattice and their associated LPPF. These data were obtained by modeling the fuel lattices with a neutronic simulator: the HELIOS transport code. The combination of the pin U235 enrichment and the Gd2O3 (gadolinia) concentration, inside the 10 × 10 fuel lattice array, was encoded by three different methods. However, the only encoding method that was able to give a good prediction of the LPPF was the method which added the U235 enrichment and the gadolinia concentration. The results show that the relative error in the estimation of the LPPF, obtained by the trained ANN, ranged from 0.022% to 0.045%, with respect to the HELIOS results. 相似文献
11.
Y. Batra D. Kabiraj D. Kanjilal 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(1):63-66
The effect of crystallinity of Ge nanocrystals on the charge storage properties of the metal oxide semiconductor (MOS) structure has been investigated. MOS structure with Ge nanocrystals embedded in the oxide has been fabricated by using atom beam sputtering technique. After annealing at 600 °C in Ar + H2 atmosphere, capacitance-voltage (C-V) measurements show flat band voltage shift of ∼0.9 V. It which is a clear indication of the memory effect of Ge nanocrystals, while unannealed structure doesnot show any hysteresis in the C-V curve. Micro Raman spectroscopy and X-ray diffraction (XRD) analyses show that crystalline content of Ge nanoparticles in the MOS structure has increased after annealing. 相似文献
12.
The addition of Th to U-based fuels increases resistance to corrosion due to differences in redox-chemistry and electronic properties between UO2 and ThO2. Quantum-mechanical techniques were used to calculate surface energy trends for ThO2, resulting in (1 1 1) < (1 1 0) < (1 0 0). Adsorption energy trends were calculated for water and oxygen on the stable (1 1 1) surface of UO2 and ThO2, and the effect of model set-up on these trends was evaluated. Molecular water is more stable than dissociated water on both binary oxides. Oxidation rates for atomic oxygen interacting with defect-free UO2(1 1 1) were calculated to be extremely slow if no water is present, but nearly instantaneous if water is present. The semi-conducting nature of UO2 is found to enhance the adsorption of oxygen in the presence of water through changes in near-surface electronic structure; the same effect is not observed on the insulating surface of ThO2. 相似文献
13.
Ferritic/martensitic (F/M) steels (T91, HT-9, EP 823) are candidate materials for future liquid lead or lead bismuth eutectic (LBE) cooled nuclear reactors. To understand the corrosion of these materials in LBE, samples of each material were exposed at 535 °C for 600 h and 200 h at an oxygen content of 10−6 wt%. After the corrosion tests, the samples were analyzed using SEM, WDX and nano-indentation in cross section. Multi-layered oxide scales were found on the sample surfaces. The compositions of these oxide layers are not entirely in agreement with the literature. The nano-indentation results showed that the E-modulus and hardness of the oxide layers are significantly lower than the values for dense bulk oxide materials. It is assumed that the low values stem from high porosity in the oxide layers. Comparison with in-air oxidized steels show that the E-modulus decreases with increasing oxide layer thickness. 相似文献
14.
Xian Zeng Qinsheng Wang Xie Meng Zhao Chen Yong Zhang 《Journal of Nuclear Science and Technology》2020,57(5):590-598
ABSTRACTOxygen measurement and control system is critical for minimizing corrosion in nuclear systems. Oxygen measurement and control tools use lead-bismuth eutectic (LBE) and pure lead as a coolant or as a spallation target. Oxygen can be supplied by either gas phase (H2O or O2) or solid phase (PbO dissolution); thus, oxygen control includes both gas phase and solid phase methods. This article focuses on oxygen concentration measurement and control of lead-bismuth eutectic in a small, static experimental facility. This facility was developed for oxygen sensor calibration and gas/solid phase control systems test programs. The oxygen sensor with Nano Cu/Cu2O closely the Nernstian behavior down to 195°C; the oxygen sensor measurement accuracy satisfied the requirements of subsequent experiments. The gas phase control system (verified according to different type of mass transfer, such as air, H2O, gas injection, and coverage) and the solid phase control system were very successful in small experimental devices. Accurate oxygen concentration control was achieved with both the gas and solid phase control systems. 相似文献
15.
S. Colominas 《Journal of Nuclear Materials》2004,335(2):260-263
A potentiometric sensor for measuring oxygen activity in LBE has been developed since 2000 until today at ‘Institut Quimic de Sarria’ electrochemistry laboratories. This sensor is based on In/In2O3 reference electrode. The last experiments performed with this sensor have been directed to characterise the sensor. For this purpose, the following experiments in stagnant conditions have been performed: effect of the operating temperature from 300 to 500 °C, different covering gases (N2 + 5% H2, Ar 99.999%, and N2 + 10 mg/L O2) and comparison of different solid electrolytes (ZrO2/Y2O3 and ZrO2/MgO). Long-term experiments have also been performed to the see the stability of the signal with time. 相似文献
16.
S.K. Sharma 《Journal of Nuclear Materials》2008,378(2):144-152
The microstructure of thermally grown oxides (TGO) and the creep properties of alloy 617 were investigated. Oxidation and creep tests were performed on 100 μm thick foils at 800-1000 °C in air environment, while the thickness of TGO was monitored in situ. According to energy dispersive X-ray (EDX) mapping micrographs observation, superficial dense oxides, chromia (Cr2O3), which was thermodynamically unstable at 1000 °C, and discrete internal oxides, alumina (α-Al2O3), were found. Consequently, the weight of the foil specimen decreased due to the spalling and volatilization of the Cr2O3 oxide layer after an initial weight-gaining. Secondary and tertiary creeps were observed at 800 °C, while the primary, secondary and tertiary creeps were observed at 1000 °C. Dynamic recrystallization occurred at 800 °C and 900 °C, while partial dynamic recrystallization at 1000 °C. The apparent activation energy, Qapp, for the creep deformation was 271 kJ/mol, which was independent of the applied stress. 相似文献
17.
Delmo A. Nishitsuji Maria C. Evora 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,265(1):135-138
Polymeric matrix composite (PMC) has been used in engineering applications instead of metal in the last few years, due to its corrosion resistance and excellent relation between tensile strength/density and elastic modulus/density. However, PMC materials cured by thermal process require high temperature and are time-consuming. The electron beam (EB) curing technology allows its use at room temperature and reduced curing times, and this is one of the main advantages over thermal technology. The aim of this work is to investigate electron beam curable epoxy formulations to use in filament winding processes to produce composite material with similar or better properties than thermal curable composites. The study has been made with commercial epoxy resins and cationic initiators. The epoxy resin samples were irradiated for few minutes with total dose of 150 kGy. The glass transition temperatures (Tg) were determined by dynamic mechanical analyzer (DMA) and the result was 137 °C. The thermal process was carried out in a furnace following three steps: 4 h at 90 °C, increasing temperature from 90 °C to 130 °C during 4 h and 12 h at 130 °C. The total process time was 20 h. The Tg of this sample was 102 °C. 相似文献
18.
Heemoon Kim Kwangheon Park Younsuk Yun Bong Goo Kim Ho Jin Ryu Ki Chan Song Yong Sun Choo Kwon Pyo Hong 《Annals of Nuclear Energy》2007
Post irradiation annealing tests were performed to obtain the Xe-133 diffusion coefficients in a SIMFUEL which was a simulated irradiated UO2 fuel with a burnup of 27,300 MWd/t U. Specimens were fabricated as cubic polycrystals with the same composition for a given burnup. Each 300 mg specimen was irradiated in the HANARO research reactor for up to a 0.1 MWd/t U burnup. Post irradiation annealing tests were carried out at 1400 °C, 1500 °C and 1600 °C. The xenon diffusion coefficients for the SIMFUEL were lower than those for UO2 in near stoichiometric UO2 due to a relatively higher concentration of the tri-valent additives, which is related to the concentration of a cation vacancy. The activation energy in the SIMFUEL was also lower than that in UO2 due to the lower formation energy of a cation vacancy and the migration energy. The xenon diffusion coefficient for the SIMFUEL increased with an increasing oxygen potential of the ambient gas. 相似文献
19.
One of the main issues regarding the design of LFR is the corrosion-erosion behaviour of materials in contact with high temperature and high velocity lead, such as pump impeller and bearing materials. Those materials will worked in lead at about 480 °C with a velocity relative to impeller blade in the magnitude of 10 m/s. Ti3SiC2, a ternary compound was selected as one of the most promising candidate material, the most significant aspect of Ti3SiC2 is that it combines some of the most attractive proprieties of ceramics with those of metals.This material was already applied in industry but more effort is needed to qualify its performance when compared with candidate structural stainless steel available in Europe. With the purpose of evaluating the corrosion resistance of Ti3SiC2, a preliminary screening test was carried out at ENEA Brasimone in fluent lead under oxidation conditions (oxygen concentration of about 10−6 wt% in the melt), with an average temperature of 500 °C and a stream velocity of about 1 m/s. 相似文献
20.
K. Natesan 《Journal of Nuclear Materials》2009,394(1):46-51
Studies were conducted on the creep behavior of Alloy 800H in impure helium and in a 1%CO-CO2 environment. At relatively low applied stresses and at low temperatures, the presence of methane in helium reduced the rupture strain significantly while increasing the rupture life relative to the behavior in pure helium. The degradation in rupture strain is due to the occurrence of cleavage fracture in the He + CH4 environment; this explanation is also supported by high activation energy (Q = 723 kJ/mol) for creep in He + CH4. At higher applied stresses and also at higher temperatures, creep-rupture behavior in He and He + CH4 was similar. Creep response in pure He and in CO-CO2 follows a dislocation climb-controlled power-law behavior whereas that in He + CH4 has a different behavior as indicated by the high stress exponent (n = 9.8). The activation energy for creep in pure He was 391 kJ/mol and in CO-CO2 was 398 kJ/mol, and appeared to be independent of stress in both environments. On the other hand, in He + CH4, the activation energy (Q = 723 kJ/mol) seems to be dependent on stress. 相似文献