Lead-bismuth Alloy Research Articles

Protection of 316L Steel Against LBE Corrosion by a CaO-MgO-Al2O3-SiO2 Glass–Ceramic Coating

A CaO-MgO-Al2O3-SiO2 glass–ceramic coating was prepared by the slurry method and subsequent sintering to improve the corrosion resistance of 316L steel in liquid lead–bismuth eutectic alloy at high temperatures. The glass–ceramic coating, sintered at 884 °C, was dense and demonstrated strong adhesion to the substrate. It was composed of the crystalline phases diopside (CaMgSi2O6) and anorthite (CaAl2Si2O8) and had an average Vickers hardness of 595 HV, which was over three times that of 316L steel. After corrosion in an oxygen-saturated, static lead–bismuth eutectic alloy at 500 °C for 1000 h, the uncoated 316L experienced significant mass gain (0.04 g) due to severe oxidative corrosion, resulting in the formation of Fe3O4 and Pb2O on its surface. In contrast, the glass–ceramic-coated specimens showed a very small mass gain (0.0012 g) after corrosion. The coating maintained good thermal stability; its crystalline phase composition remained largely unchanged after the corrosion test. The glass–ceramic coating still exhibited dense microstructure and tightly adhered to the substrate after corrosion. There was no evident penetration of lead–bismuth into the coating, and no dissolution of the coating’s elements into the lead–bismuth alloy was detected. These observations confirm that the glass–ceramic coating possessed superior corrosion resistance in liquid lead–bismuth eutectic environments.

The Effect of Temperature on the Hugoniot Elastic Limit and the Spall Strength of a Lead–Bismuth Alloy at the Pressure of Shock Compression up to 2.4 GPa

The Effect of Temperature on the Hugoniot Elastic Limit and the Spall Strength of a Lead–Bismuth Alloy at the Pressure of Shock Compression up to 2.4 GPa

Vitrification of lead–bismuth alloy nuclear waste into a glass waste form

AbstractLead–bismuth eutectic (LBE), a promising coolant in advanced nuclear systems, can be activated by neutrons during nuclear reactor operations. The decommissioning of nuclear facilities would generate lead–bismuth (Pb–Bi) alloy‐contaminated nuclear waste. The current metallic nuclear waste treatment approach involves remelting followed by cementitious solidification. This increases the waste volume and the risk of radionuclide migration in groundwater. Therefore, this study developed a method for vitrification of Pb–Bi alloy waste. Different amounts of SiO2 were added at 750–1100°C in the air to turn the simulated LBE waste into glass waste form. The values of the normalized elemental leaching rates (Pb, Bi, Si, Te, and Ni) determined using the 28‐day static leaching test were less than .2 g m−2 d−1 and varied with SiO2 addition. Furthermore, a three‐stage evolution of the glass structure with SiO2 addition was proposed according to the structural analysis performed using Raman and X‐ray photoelectron spectroscopies. The evolution stages were as follows: (i) the stage of heavy metal transition from covalent to ionic heavy metals (7.5 wt% < SiO2 < 15 wt%), (ii) the stage of increase in bridging oxygen (15 wt% < SiO2 < 20 wt%), and (iii) the stage of domination of the Si–O network (20 wt% < SiO2 < 25 wt%). The evolution of the glass structure resulted in varying glass chemical durability. Finally, the glass‐forming region of (20–48)PbO–(35–70)Bi2O3–(7.5–25)SiO2 (wt%) and the temperature needed to melt those glasses were determined through the melting test, where radionuclides and toxic heavy metals showed undetectable volatilization during vitrification. Hence, turning LBE waste into glass waste form will be a potential approach for treating Pb–Bi alloy nuclear waste.

Improved cellular automata modeling of corrosion/oxidation mechanism of stainless steel in LBE

In recent years, small modular reactors (SMRs) have garnered significant attention, and small modular natural circulation lead or lead-alloy-cooled fast reactors (LFRs) are among the potential choices for SMR development. However, the issue of metal corrosion in a high-temperature environment by liquid lead–bismuth eutectic (LBE) persists in small modular natural circulation LFRs. The primary current method for addressing this problem involves dissolving a certain amount of oxygen in LBE to form an oxide layer on the inner surface of the piping as a corrosion inhibitor. The structural evolution of the oxide layer on stainless steel surfaces under the influence of LBE is a complex nonlinear process. Existing experiments and research have indicated that the oxide layer is a biphasic oxide layer. However, due to the limited and scattered results from current experimental studies, predicting the long-term corrosion of steel in liquid lead–bismuth alloys remains a challenge. To further understand the formation principles of the biphasic oxide layer and the factors influencing its formation process, this study established a cellular automata model that combines surface growth and internal corrosion oxidation to simulate the corrosion of stainless steel, the diffusion of iron/oxygen elements on the oxide layer, and the precipitation of iron on the oxide layer using the cellular automata method. The diffusion process was simulated using a random walk model. The approximate characteristics of the evolution of the involved processes were explored based on the simulation results. The simulation results showed that the cellular automata method can accurately simulate the formation of the biphase oxide film in this complex process from a mesoscopic scale.

CFD-моделирование теплообменных пучков парогенератора с эвтектическим сплавом «свинец-висмут»

CFD-моделирование теплообменных пучков парогенератора с эвтектическим сплавом «свинец-висмут»

A Review of Corrosion Behavior of Structural Steel in Liquid Lead–Bismuth Eutectic

Liquid lead–bismuth eutectic alloy is one of the candidate coolants for fourth-generation nuclear power systems because of its good physical and chemical properties, neutron economic performance, and safety. However, the compatibility between the coolant and structural steel is still the main factor restricting its large-scale industrial application in the nuclear energy field. Structural steel in a liquid lead–bismuth eutectic alloy for a long time would cause severe corrosion. The erosion of structural steel by high-flow-rate liquid lead–bismuth alloy will lead to a more complex corrosion process. This paper mainly reviews the corrosion characteristics of liquid lead–bismuth and the corrosion behavior of structural steel in liquid lead-bismuth eutectic. The main methods of inhibiting liquid lead–bismuth corrosion are summarized, and future research directions are suggested.

Numerical simulation of centrifugal pump impeller erosion caused by particles in lead–bismuth alloy

In order to study the influence of solid particles in lead–bismuth alloy on the safety of nuclear main pump, DPM (Discrete Phase Model) is used to calculate the wear rate of the impeller of nuclear main pump under different operating conditions. By comparing the erosion rate and the most severe erosion area under different working conditions, the most unfavorable operating conditions are obtained. The results show that the erosion of impeller caused by solid particles is the most serious when the inlet velocity of particles u is 0.4[Formula: see text]m/s and particle size D is 100[Formula: see text][Formula: see text]m. Under the small particle size, the impeller erosion concentrated on the suction side of the blade, and under the large particle diameter, the erosion concentrated on the pressure side, and the erosion is more serious. With the increase of solid particle velocity, the erosion of the impeller increases first and then decreases. The erosion severity of impeller and front and rear cover plates caused by solid particles is not consistent. The above research can provide guidance for the anti-wear design and safe operation of the nuclear main pump impeller.

Numerical Simulation on Turbulent Flow Characteristics Analyzation of Lead-Bismuth Alloy in Narrow Rectangular Channel

Numerical Simulation on Turbulent Flow Characteristics Analyzation of Lead-Bismuth Alloy in Narrow Rectangular Channel

The effect of temperature on the Hugoniot elastic limit and the spall strength of a lead-bismuth alloy at the pressure of shock compression up to 2.4 GPa

Measurements of the Hugoniot elastic limit and the spall strength of the eutectic alloy Bi --- 56.5 mass%, Pb --- 43.5 mass% were carried out at sample temperatures in the range of 20-109oC based on registration and analysis of the evolution of shock compression pulses of various amplitudes. It is shown that an increase in the temperature of the samples leads to a decrease in the Hugoniot elastic limit by 25%, and the spall strength of the alloy under study --- by 30%, regardless of the strain rate. An increase in the strain rate by two orders of magnitude leads to an increase in the spall strength by about three times. Approximation power-law dependences of the decay of the elastic precursor on the thickness of the samples and the spall strength on the strain rate before fracture at normal and elevated temperatures are constructed. Keywords: lead-bismuth eutectic alloy, shock waves, deformation, temperature, Hugoniot elastic limit, spall strength.

Comparison study of thermoclinic heat storage tanks using different liquid metals for concentrated solar power

Liquid metals are good potential heat transfer materials for thermoclinic heat storage (THS) systems and will play an important role in the next generation solar thermal power system with higher operating temperature. This paper presents a comparative research work on the charging, discharging and mechanical performances of THS tanks based on four different liquid metal materials, which are lead (Pb), lead-bismuth alloy (PbBi), sodium (Na) and sodium-potassium alloy (NaK). The analysis results indicate that for both the charging and discharging processes, the lead-based THS tank can have the shortest operating duration, largest charging and discharging quantities (9.78 × 109 J and 9.21 × 109 J) as well as the highest discharging efficiency (94.17%), revealing its best operating performance. Relatively acceptable operating performances of lead-bismuth-based and sodium-based THS tanks are also demonstrated. Furthermore, in contrast with other three liquid metals, the lead-based THS tank also has the best mechanical performance. It has the smallest peak maximum mechanical stress of the steel wall (58.6 MPa). In summary, the lead-based THS tank has both the best heat storage and mechanical performances.

Feasibility study mixed oxide fuel tests in the impulse graphite reactor

The article presents the results of computational studies to substantiate the possibility of testing the fuel of the Multipurpose hYbrid Research Reactor for a High-tech Applications reactor (MYRRHA) in the Impulse Graphite research Reactor (IGR). A scheme for conducting experiments is proposed, which allows simulating the operating conditions of MYRRHA fuel elements in a wide range of changes in their thermohydraulic parameters, including the conditions of accidents with the destruction of fuel pellets, blocking the flow area and stopping the coolant flow. A method for thermohydraulic calculations has been developed, implemented in the software environment of the computational fluid dynamics (CFD) code. A computational model of the experimental device is developed, optimized according to the spatial partitioning grid. A turbulence model for determining the parameters of convective heat and mass transfer in a eutectic lead-bismuth alloy is selected and substantiated.

CONV-3D Code-Aided Calculation of the Free-Convective Flow Parameters of Lead–Bismuth Alloy in a Cavity with a Transverse Temperature Gradient

CONV-3D Code-Aided Calculation of the Free-Convective Flow Parameters of Lead–Bismuth Alloy in a Cavity with a Transverse Temperature Gradient

A high-entropy alloy nitride protective coating for fuel cladding in high temperature lead-bismuth eutectic alloy

High temperature coatings possess great potential for improving operation temperature of 4th generation nuclear reactor. In this paper, a high-entropy alloy nitride coatings (CrAlTiNbV)Nx were investigated for the application in corrosive lead-bismuth alloy (LBE). The coatings were synthesized by unbalanced magnetron sputtering on ferritic/martensitic (F/M) steel. Properties of (CrAlTiNbV)Nx are systematically investigated from perspective of the electron structure, crystalline, and mechanical properties under different bias voltage applied on samples. Significant improvement of hardness (30 GPa) is obtained at bias voltage of -156 V. Furthermore, the corrosion behavior in 550 °C lead bismuth eutectic (LBE) was conducted for 1200 h with saturated oxygen content, which demonstrates the dense structure of coatings with no obvious crack, spallation that characterized by the SEM, EDS, and TEM. Upon the application of high bias voltage, more prone formation of high-density grain boundary with fine grains extends the diffusion path of Pb and Bi are achieved for excellent LBE corrosion resistance. Our work not only provide an insight to the electron structure of high entropy alloy nitrides, but also shows a potential application for (CrAlTiNbV)Nx protecting fuel cladding in the next generation lead based reactor.

Experimental Investigation on the Cleaning Effect and Influence Rule of Hydrogen Peroxide–Acetic Acid on Lead–Bismuth Eutectic Alloy

During the refueling process of lead–bismuth eutectic (LBE)–cooled fast reactors, lead–bismuth alloy can easily adhere to the surface of the fuel rod clads when spent fuel assemblies are unloaded from the reactor core. For some designs, the lead–bismuth alloy attached on the spent fuel rods will be cleaned via physical or/and chemical methods prior to their transportation, storage, and reprocessing. In this article, the cleaning effect of a washing lotion composed of hydrogen peroxide (H2O2) aqueous solution and concentrated acetic acid (CH3COOH) as the main components on LBE was experimentally investigated. By adjusting the composition ratio of the washing lotion and the reaction temperature, the law of their influence on the cleaning effect of LBE was determined. The optimal washing lotion composed of 30 Vol% hydrogen peroxide aqueous solution as oxidant, 40 Vol% concentrated acetic acid as acid, and 30 Vol% ultrapure water as the solvent was proposed based on experimental investigations. The optimal working temperature range was also obtained. The reaction intermediate product was characterized with the XRD analysis in order to understand the reaction mechanism. The composition of the released gas (even in a slight amount) was also analyzed with gas chromatography. The hydrogen concentration in the released gas was found to be lower than the detection limit of gas chromatography (10 ppm). Since the explosion limits of hydrogen at atmospheric pressure are between 3.95 and 75.73 Vol%, the risk of possible hydrogen explosion is concluded to be extremely low. Therefore, no special treatment of the released gas is required even in a large-scale industrial platform. Furthermore, corrosion effect of the washing lotion on austenitic stainless steel components was tested as well and found to be negligibly small. The relative mass loss of the thin-walled stainless steel samples immersed in the washing lotion was found to be less than 0.5% after an experimental duration of 144 h, which facilitates sufficient cleaning time in future industrial applications.

Electrochemical Production of Bismuth in the KCl-PbCl2 Melt.

An anode dissolution of binary metallic lead–bismuth alloys with different concentrations of components has been studied in the KCl–PbCl2 molten eutectic. The dissolution of lead is found to be a basic process for the alloys of Pb–Bi (59.3–40.7), Pb–Bi (32.5–67.5), Pb–Bi (7.0–93.0) compositions in the whole interval of studied anode current densities. A limiting diffusion current of lead dissolution was observed at 2 A/cm2 and 0.1 A/cm2 for the alloys of Pb–Bi (5.0–95.0) and Pb–Bi (3.0–97.0) compositions, respectively. The dissolution of bismuth takes place at the anode current densities exceeding the mentioned values. The number of electrons participating in the electrode reactions is detected for each mechanism. Based on the theoretical analysis, the experimental electrolysis of bismuth was performed in the laboratory-scale electrolytic cell with a porous ceramic diaphragm. The final product contained pure bismuth with a lead concentration of 3.5 wt.%.

Investigations of regularities in the accumulation of hydrogen-reduced slags in circulation circuits with lead-containing coolants

The paper presents a computational analysis of regularities in the accumulation of slags during the interaction of lead and lead-bismuth coolants with oxygen gas. Oxidation of lead-containing coolants will cause the formation of lead oxide, while the formation of bismuth oxide is unlikely. Dosed supply of oxidizing gas to lead-containing coolants makes it possible to oxidize, selectively, chromium and nickel to their oxides without the slag formation from solid lead oxide. Regularities were studied which are involved in the lead oxide formation during the interaction of lead-containing coolants with oxygen gas. It has been found that, in the process of interacting with oxygen gas, a lead-bismuth alloy is oxidized 1.7 times as intensively as lead, this being explained by the presence of bismuth in the alloy. Bismuth is oxidized more intensively than both lead and the lead-bismuth alloy. The inert gas overpressure during depressurization does not prevent air oxygen from entering the circuit, and the dependence of the nitrogen and oxygen flow into the circuit on the argon flow out of the loop is close to linear regardless of the circuit state (cold, without coolant; heated, without coolant; heated, with circulating coolant). Oxygen is a chemically active impurity and is absorbed by the circuit; it is therefore important to control nitrogen in the gas spaces of the reactor and research plant circuits with lead-containing coolants. This will make it possible to signal, in a timely manner, the ingress of oxygen into the circuit and to take measures required to avoid or reduce the scale of the slag formation from lead oxides.

ТЕПЛОФИЗИЧЕСКИЕ ИССЛЕДОВАНИЯ: ОТ ПЕРВОГО СТЕНДА К КРУПНОМАСШТАБНОЙ АТОМНОЙ ЭНЕРГЕТИКЕ

The article presents the main research results of thermal physicists of the IPPE from its inception to the present time. Research results in the areas of heat and mass transfer and hydrodynamics of coolants (liquid metals, water), physical chemistry and technology of liquid metal coolants for nuclear power plants for various purposes (nuclear power plants, nuclear submarines, space nuclear power plants), development codes, innovative projects, non-nuclear technologies for the use of liquid metals, heat pipes, analysis and generalization of thermophysical data are considered in the article. As a result of a large complex of experimental and computational studies, the fundamental physicochemical and thermohydraulic regularities of the coolant - impurities - structural materials - protective gas have been studied, scientific foundations have been created for the use of liquid metal coolants in nuclear power. Studies have been carried out to substantiate the technical and economic characteristics of nuclear fuel for operating, under construction and future NPPs of VVER RP, design solutions for passive safety, technical solutions and hydrogen safety devices, heat removal from the reactor through a steam generator and PHRS in case of beyond design basis accidents. As well as design solutions and safety for NPP designs with BN-1200 reactor with sodium coolant, BREST-OD-300 reactor with lead coolant, SVBR-100 reactor with lead-bismuth alloy, MBIR research reactor. The results of these studies made it possible, together with institutes and design organizations, to scientifically substantiate thermal-hydraulic parameters and highly efficient technological processes, develop and practically implement devices and systems that ensure the successful operation of fundamentally new nuclear power plants cooled by water and liquid metals, with original scientific and technical solutions that had no analogue in world practice. R&D works were carried out to substantiate the innovative project VVER with supercritical pressure, the concept of an electro-nuclear subcritical blanket based on the modular principle of constructing an core with liquid-salt melts of fissile materials, studies of thermal hydraulics, mass transfer of high-temperature sodium and the development of a combined coolant purification system to justify the BN-HT reactor with temperature sodium ~900 °C for hydrogen production. The directions of investigations at the present stage are discussed.

Uncertainty analysis in coupled neutronic/thermal-hydraulic calculations based on computational fluid dynamics

There is an inevitable uncertainty in the coupled neutronic/thermal–hydraulic calculations, which are used for simulating the performance of nuclear reactors, due to the influence of design parameters and initial conditions. The application of uncertainty analysis methods in such calculations can reduce the “uncertainty zone” of calculation results as well as the unnecessary safety margin of the reactor. In this study, based on the combination of user-defined function (UDF) of FLUENT, a computational fluid dynamics (CFD) code, with the neutron dynamics model, fuel pin heat transfer model, and SIMLAB software, an uncertainty analysis platform called CFD/PFS is developed. The CFD/PFS platform is used to simulate the unprotected transient overpower (UTOP) accident in the small modular natural circulation lead–bismuth alloy cooled fast reactor-10MWth (SNCLFR-10) reactor, which is followed by uncertainty quantification. The results of uncertainty and sensitivity analysis justify the good reliability and accuracy of coupled neutronic/thermal–hydraulic calculations. The titular values of transient parameters, such as peak reactivity and peak fuel temperature, are within the bilateral tolerance limits, and the relative deviation between these values and the limit values is less than 3.95%. As far as UTOP accident, Doppler coefficient is found to be the main source of uncertainty, which has the most significant effect on reactor safety.

Characterization of structure and superconducting properties of low-temperature phase of Pb-Bi alloy films

Lead-bismuth (Pb-Bi) alloys, as a superconducting material, have been widely studied at their superconducting transition temperatures and the critical magnetic fields for different composition ratios. Most of experimental studies focused on the stable ε phase formed at high temperatures, but less on the Pb-Bi alloys grown at low temperatures. So far, the structural and superconducting properties of the low-temperature Pb-Bi phases are far from good understanding. Here, we report our investigation of structural and superconducting properties of a low-temperature phase of Pb-Bi alloy. The Pb-Bi alloy films with a nominal thickness of about 6 nm are prepared by co-depositing Bi and Pb on Bi(111)/Si(111)-(7 × 7) substrates at a low temperature of 100 K followed by annealing at a treatment of 200 K for 2 h. The structural and superconducting properties of the Pb-Bi alloy films are characterized in situ by using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS). It is observed that the spatially separated phases of nearly pure Bi(111) domains and Pb<sub>1–<i>x</i></sub>Bi<i><sub>x</sub></i> alloy domains are formed in the films, where these phases can be identified by their distinct differences in the atomic structure and the distributions of step heights in the atomically resolved STM images, as well as by their distinguished STS spectra. The Pb<sub>1–<i>x</i></sub>Bi<i><sub>x</sub></i> alloy phase presents the structure of Pb(111), in which about <i>x</i> ≈ 0.1 Bi is substituted for Pb. The STS spectra show that the Pb<sub>1–<i>x</i></sub>Bi<i><sub>x</sub></i> alloy phase is superconducting, with a transition temperature <i>T</i><sub>c</sub> = 7.77 K derived from the variable-temperature measurements. This transition temperature is higher than that in pure Pb film (6.0–6.5 K), which can be well explained by the Mattias rules, with considering the fact that the average number of valance electrons increases after Bi atoms with five valance-electrons have been substituted for Pb atoms with four valance-electrons. The analysis shows that the ratio <inline-formula><tex-math id="M1">\begin{document}$ 2\Delta (0)/{k_{\rm{B}}}{T_{\rm{C}}}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20210482_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20210482_M1.png"/></alternatives></inline-formula> is about 4.94 with the superconducting gap <inline-formula><tex-math id="M2">\begin{document}$ \varDelta (0) = 1.66$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20210482_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="17-20210482_M2.png"/></alternatives></inline-formula> meV at 0 K, indicating that the Pb<sub>1–<i>x</i></sub>Bi<i><sub>x</sub></i> alloy is a strongly-coupled superconductor. The non-superconducting Bi(111) and the superconducting Pb<sub>1–<i>x</i></sub>Bi<i><sub>x</sub></i> alloy domains form an in-plane superconductor-normal metal-superconductor (S-N-S) Josephson junction. The proximity effect in the Bi(111) domains is measured at different N-S junctions, which suggests that the lateral superconducting penetration length in Bi(111) might be affected by the area of the quasi-two-dimensional interface. The superconducting gap in the Bi(111) region with a narrow width of 23 nm in an S-N-S Josephson junction is found to be greatly enhanced due to the existence of multiple Andreev reflections. Since Bi can host potential topological properties, the lateral Bi(111)-Pb<sub>1–<i>x</i></sub>Bi<i><sub>x</sub></i> heterostructures, because of the existing proximity effect, could have potential applications in exploring the novel topological and superconducting phenomena.

Study on Natural Circulation Heat Transfer Characteristics of Different Liquid Metals Based on Factor Analysis

The study of the commonness and differences of natural circulation of different liquid metals plays an important role in improving the safety of reactors. The numerical simulation of liquid metal natural circulation heat transfer was carried out by CFX, and its heat transfer coefficient, flow, and outlet temperature were studied. The factor analysis method was used to analyze the influence of the interaction between factors and the contribution rate of each factor. It can be found that the commonality of heat exchange between different liquid metals is that the heat transfer coefficient is mainly affected by the power, the contribution rate of power to the heat transfer coefficients of liquid sodium, sodium-potassium alloy, lead and lead-bismuth alloy reached 40.16%, 78.16%, 97.95% and 92.19%, respectively; the flow rate and outlet temperature of the liquid metal increase with the increase of power; the flow rate and outlet temperature are hardly affected by pressure. The difference is that the heat transfer coefficients of liquid metals have different trends with the change of power; in addition, the interaction between the factors of heat transfer coefficient is different; the heat transfer coefficient of liquid sodium and sodium-potassium alloy is affected by pressure, the pressure affects the heat transfer coefficient by coupling with power or inlet temperature. In general, the heat transfer performance of sodium is the best，with a much higher heat transfer coefficient than the other three liquid metals；the natural circulation ability of sodium-potassium alloy is the strongest, and its flow velocity is greater than other liquid metals.