Lead-bismuth Eutectic Research Articles

Interfacial microstructure and corrosion behavior of ODS FeCrAl alloy in oxygen-saturated lead-bismuth eutectic at 450 °C

The interfacial microstructure and corrosion behavior of oxide dispersion strengthening (ODS) FeCrAl alloy with 20 wt% Cr (e.g. 20Cr ODS FeCrAl alloy) exposed to static oxygen-saturated lead-bismuth eutectic (LBE) at 450 °C for 20 h, 40 h, 60 h, 80 h and 100 h as exposure time respectively have been investigated. The results show that multilayer corrosion films of 20Cr ODS FeCrAl alloy can exist at the corrosion interface. Due to formation of protective scales, the primary corrosion mechanism of 20Cr ODS FeCrAl alloy in LBE is oxidation rather than dissolution and penetration of liquid LBE. Specially, the spinel-shaped nano-sized dense external layer without any microcracks is obviously observed. Moreover, the dense and compact scale with micron-meters, i.e. Al-rich Fe-Cr spinel, generates at interface as the middle layer to effectively defend inward diffusion of oxygen and penetration of LBE. Meanwhile, a reinforced and continuous internal layer mixed with Cr2O3 scale and the ferrite inner oxidation zone (IOZ) existing in the form of the interlocking interface between the layers and the substrate can further promote the adhesion between corrosion layers and the substrate of 20Cr ODS FeCrAl.

Microstructure, mechanical and oxygen-deficient lead-bismuth eutectic corrosion properties of FeCrAlTiMo high-entropy alloy coatings for fuel claddings

The FeCrAlTiMo high-entropy alloy (HEA) coatings were deposited on the ferritic/martensitic (F/M) steel fuel cladding tubes by magnetron sputtering technology to improve their lead-bismuth eutectic (LBE) corrosion resistance. The effects of bias voltage on the microstructure, mechanical and LBE corrosion properties of the FeCrAlTiMo coatings were systematically investigated. The LBE corrosion test shows that the coatings with a bias voltage of −150 V exhibit the best oxidation resistance after exposed to the oxygen-deficient LBE at 600 °C for 500 h, and can be used as a protective candidate coating material for lead-cooled fast reactor (LFR) application. The high-temperature LBE corrosion mechanism of the FeCrAlTiMo coatings under deficient oxygen concentration was also discussed in detail.

Numerical simulation of boiling dynamics in liquid Lead-Bismuth injected with multi-rupture high-pressure water jets

Once a steam generator tube rupture (SGTR) accident occurs in a lead-based fast reactor, it can trigger a domino effect of heat transfer tube ruptures, leading to a loss-of-flow accident involving multiple ruptures. This paper employs numerical methods to investigate the jet boiling phenomenon associated with the injection of sub-cooled water into high-temperature lead‑bismuth eutectic (LBE) through multiple nozzles. It explores how nozzle spacing, number, and diameter impact jet characteristics. Additionally, it analyzes flow characteristics and heat transfer mechanisms from the perspective of jet interaction. The study identifies critical areas within the multi-nozzle jet, specifically the three-phase mixing region, LBE entrainment region, water core region, and steam plume region. In scenarios where nozzle spacing is narrow or nozzle diameters differ significantly, the jet's base may undergo fragmentation. The jet process is categorized into two stages: the transition stage and the stable stage. During the stable stage, the mass flow rate of sub-cooled water remains relatively constant, with nozzle spacing exerting minimal influence on it. When considering the cross-sectional area of a single nozzle, an increase in nozzle diameter elevates the normalized mass flow rate, whereas the number and diameter of nozzles have little effect on it. Jet penetration depth is inversely related to nozzle spacing. As the number and diameter of nozzles increase, penetration depth initially rises and then decreases. Nozzle spacing has a minor influence on the jet's steam volume, while the number and diameter of nozzles are positively correlated with steam volume. Conversely, the number and diameter of nozzles negatively correlate with normalized steam volume.

Microstructural characteristics of the internal oxidation zone of ferritic/martensitic steel exposed to LBE at 550°C for 1000 h

The oxidation products formed on ferritic/martensitic (F/M) steel exposed to oxygen-saturated lead-bismuth eutectic (LBE) at 550 °C for 1000 h were investigated using various characterizations. The results indicate that the corrosion products consist of three distinct layers from the inside to the outside: the inner oxidation zone (IOZ), a middle oxide layer, and the growth front facing LBE. In the IOZ, although O has penetrated the entire oxidation layer, the martensite laths and ferrite grains remain visible. However, significant segregation of Cr and O along the laths and grain boundaries has occurred, resulting in the formation of strip-shaped Cr2O3 particles. In the matrix adjacent to the IOZ, Cr atoms have segregated at the grain boundaries and martensite laths, forming Cr-rich regions, while O atoms have not yet infiltrated. During the growth of Fe3O4 grains, the priority formed strip-shaped Cr2O3 particles are pushed toward the corrosion front until they detach from the F/M steel and disperse into the LBE, resulting in nearly pure Fe3O4 grains in the middle layer. The gradient three-layer structure of the oxidation product is closely associated with the segregation of Cr and the gradient distribution of oxygen partial pressure (PO2).

Insight into the fretting corrosion behavior of 316L steel in liquid lead-bismuth eutectic at 500°C

Due to flow induced vibration caused by coolant circulation, fretting corrosion inevitably occurs between fuel cladding, heat exchanger tubes and their holders in Gen IV lead-bismuth eutectic (LBE) cooled nuclear reactors. In the current work, fretting corrosion behavior of 316 L steel in oxygen-saturated LBE at 500 °C has been investigated. It is shown that within the gross slip regime, the microstructure under fretting interface presents a stratified structure, composed of third body layer, oxide scales and plastic deformation layer. At the early stage of fretting corrosion, the dominant damage mechanism is fretting wear, showing that the thickness of third body layer is much larger than that of oxide scale. As fretting time increases, the dominant damage mechanism is gradually changed to LBE corrosion and fretting wear together, as the visible oxide scale is formed next to the third body layer. Moreover, the growth rate of oxide scales under fretting interface is accelerated by over an order of magnitude compared to that when 316 L steel exposed to LBE directly. In particular, after 60 h exposure, the thicknesses of oxide scale related to the worn and unworn regions are ∼4.5 μm and ∼0.2 μm, respectively. The occurrence of such phenomenon is thought to be ascribed to the severe plastic deformation under fretting contact interface, since the crystal defects served as perfectional nano-channels can promote the diffusivity of oxygen atoms. In addition, the acceleration diffusivities of oxygen atoms caused by the local high contact stress may also be responsible for this matter.

A subchannel analysis code for advanced liquid metal fast reactor cores and study on heat transfer characteristics of core geometry parameters

The liquid metal fast reactor represents an important reactor type for the future development of nuclear energy. Accurately modeling and predicting the subchannel flow and heat transfer phenomenon in the rod bundles plays a key role in ensuring core safety. Consequently, a subchannel code suitable for the liquid metal fast reactor is analyzed based on the subchannel analysis code of the Pressurized Water Reactor (PWR). The modified code incorporates various types of liquid metals, such as lead, lead-bismuth eutectic (LBE), and sodium, along with their constitutive models, enhancing the applicability of the liquid metal reactor systems. This code has been verified and validated at several levels, including comparing the code simulation results with other similar subchannel codes results, high-dimensional Computational Fluid Dynamics (CFD) simulations, and experiment data. The sensitivity analysis of core geometric parameters and turbulent mixing coefficients is performed based on the modified version code. The influence of the core geometry, including the rod Pitch to Diameter ratio (P/D), Rod to Wall gap (RTW) and the wire wrap pitch (H) on the sensitivity of outlet temperature has been investigated. The results show that the new subchannel analysis code suitable for liquid metal cooled reactor shows reasonable agreement with the verified and validated results. The geometric parameters, such as P/D, RTW and H have noticeable effects on the outlet temperature difference of the subchannels. Additionally, the outlet temperature distribution in the subchannel is significantly affected by different turbulent mixing coefficients and the distribution of the turbulent mixing coefficient also influenced by the reactor core sizes. Overall, this study could support the rod bundles design and safety analysis in the liquid metal reactors.

A Study on the Fretting Corrosion of 316L in Static Lead-Bismuth Eutectic (LBE): the Role of Slip Amplitude and Normal Force on Damage Mechanism at 350 °C

Fretting corrosion of stainless steel in the LBE affects the safety of lead-cooled fast reactors. Slip amplitude and normal load are the main mechanical factors affecting fretting wear behavior. Thus, the damage mechanism of 316L stainless steel at 350 °C LBE influenced by slip amplitude and normal load was investigated by jointly utilizing multiple characterization methods. The results indicate that the normal load and slip amplitude essentially affect the tangential stress and relative sliding value in the contact area, leading to different slip regions and damage mechanisms. In the mixed slip region, the damage mechanism is adhesion and delamination cracks. The increase in tangential stress leads to decrease in relative sliding. The thick wear debris layer attached to the worn surface can protect the substrate from being attacked by the LBE. In the gross slip region, the damage mechanism is abrasive wear and dissolution corrosion. The increase in relative sliding causes more damage and Ni dissolution, leading to the transformation from austenite to ferrite and internal strain, making the substrate more susceptible to damage and increasing the risk of liquid metal embrittlement (LME) of austenitic stainless steel at 350 °C. Accordingly, a model for different damage mechanisms was proposed. These results can provide important information on the fretting damage related to the LBE environment.

Tensile and cracking behavior of thin-walled 316Ti austenitic steel after exposure to 550 °C lead-bismuth eutectic with different oxygen concentration

The corrosion evolution of 316Ti steel in 550°C lead-bismuth eutectic (LBE) with oxygen concentrations (Co) of 5×10-6 wt.% and 5×10-8 wt.% and their impact on the tensile behavior were investigated in this study. The steel primarily underwent oxidation at Co of 5×10-6 wt.%, slightly influencing the tensile strength and elongation of specimen within 1000 hours exposure. In contrast, the structural integrity and tensile strength of specimen were significantly deteriorated at Co of 5×10-8 wt.% where the steel mainly experienced dissolution corrosion. The cracking behaviors of oxide layer and ferrite layer, and their influences on the failure of thin-walled specimen were discussed. Special concerns should be raised on the detrimental effect of localized corrosion, such as intergranular oxidation, LBE-wetted precipitate bands and dissolution pits, since cracks are expected to initiate easily in these zones and propagate into steel matrix under tension, potentially leading to the premature failure of thin-walled components.

Large Eddy simulation on the Lead-Bismuth Eutectic jet at reactor core outlet

The Lead-Bismuth Eutectic (LBE) Cooled Fast Reactor (LFR) represents a promising Generation-IV technology, anticipated to offer a sustainable, safe, and clean energy solution. LBE fluid from LFR assemblies varies in temperature, causing violent temperature oscillations during the jet mixing that may contribute to structural fatigue, threatening LFR safety. This study focuses on investigating the critical thermal–hydraulic phenomena occurring at the core outlet of the LFR by modeling the assembly head in a realistic reactor configuration. Large Eddy Simulation (LES) is employed to explore the LBE jet characteristics in a three-head model with varying inlet parameters. The analysis includes the fluctuation patterns of both the flow and temperature fields downstream of the assembly head. The results show that the influence area of the assembly head is mainly in the range of about 0–175 mm downstream of the outlet of the assembly head. The temperature fluctuation frequency is the highest near the assembly head, typically within 20 Hz, and the temperature fluctuation frequency in other areas is lower. These findings provide valuable insights for designing LFRs and understanding the flow and heat transfer behavior of liquid metals.

Enhancing corrosion resistance of T91 F/M steel in liquid lead-bismuth (LBE) by slurry FeAl coating

A FeAl coating was fabricated on T91 steel via slurry aluminizing. The corrosion behavior of coated and uncoated samples was assessed in static LBE (lead-bismuth eutectic) with two both high and low dissolved oxygen concentrations at 550 °C. The coating was mostly intact and exhibited great corrosion resistance compared to the uncoated specimens regardless of the oxygen concentration. That is because the coating can form a protective alumina film on the surface at extremely low dissolved oxygen level. This coating is of significant engineering value in enhancing the corrosion resistance of Fe base alloy in LBE.

Forms of occurrence metals and metalloids in products of the Mutnovsky volcano gas-hydrothermal activity

On the basis of concentrate analysis of the Mutnovsky volcano thermal sites substance, new data of the ore elements forms of occurrence were obtained. In the course of large-scale hydrothermal alteration of volcanic rocks, with the participation of magmatic fluids and meteoric waters, metals and metalloids are transported to the surface, which are concentrated in the form of the main or impurity components of new-forming minerals. Sulfides of copper, zinc, mercury, silver and barium sulfate are confidently diagnosed, in which, in addition to mineral-forming Zn, Cu, Hg, Ag and Ba, admixtures of Mn, Cd, Sr, I, Cl, Te, Pb are present. Micron-sized phases were found containing Ru, Os and Ir (laurite), Pb (galena) as the main components, as well as intermetallic compounds (Fe–Ni), (Fe–Ir–Os), (Pb–Bi), (Bi–Te) and native Au. Most of the new-forming mineral individuals are associated with a mineral of the pyrite-marcasite group, which contains admixtures of As, Cu, Ni, and Co. Platinoids Os, Ir, Ru among the new-forming minerals within the East Kamchatka volcanic belt were discovered for the first time.

Numerical Study on Characteristics of Lead-Bismuth Lubricated Hydrodynamic Bearing Considering Non-Condensable Gas

Lead-Bismuth Eutectic (LBE) is an interesting candidate as a coolant for Generation IV nuclear power plants. Lead-bismuth lubricated radial guide bearing is the key component of the mechanical pump in a lead-bismuth coolant system. In this paper, the transient calculation model of multiphase lubrication flow field of journal bearing is established by using Singhal full cavitation model and structured dynamic grid technique. Due to the saturated vapors of LBE being very low, the effects of different Non-Condensable Gas (NCG) contents on the characteristics of lead-bismuth lubricated journal bearing systems were analyzed. The results show that the NCG content has an obvious influence on the working state of the bearing. With the increase in NCG content, the bearing load capacity decreases. Under the same load, with the increase in NCG content, the eccentricity of the static equilibrium position will be larger, which will increase the risk of bearing contact with the bearing bush. Moreover, the increase of NCG content will lead to the increase of tangential oil film force work, which is helpful to improve rotor stability.

LBE corrosion behavior of helium pre-irradiated martensitic steel

In the design of the spallation target of CiADS, T91 steel was selected for the most critical component, the beam window. A Si-modified martensitic steel (SIMP) has been currently developed, which has better corrosion resistance and is planning to replace T91 as a material of beam window in the future. In order to assess the effect of irradiation damage on the microstructure evolution and corrosion behavior of the SIMP, the pre-irradiated samples with irradiation doses from 5 × 1015 to 3 × 1017 He/cm2 exposed in static lead-bismuth eutectic (LBE) with saturated oxygen at 350 °C for 4000 h were investigated. Results show that pre-irradiation neither change the double-layer structure of the oxide layer nor significantly affect the corrosion rate. This may be due to the slow diffusion of elements at low temperatures, and the low irradiation dose not reaching the threshold for triggering accelerated corrosion.

Revealing wear mechanisms of coated shafts in low-speed journal bearings immersed in liquid Lead-Bismuth Eutectic (LBE)

This study investigates wear mechanisms of coated shafts in journal bearings within liquid lead-bismuth eutectic. Shafts were coated with TiAlN, a-C:H, multi-layer TiAlN with sputtered carbon, and chrome plating. Bearings made from sintered iron with carbon inclusions (DEVA 120 and DEVA 121) were tested in LBE at 200 °C and 50 rpm using a dedicated test rig. The a-C:H coatings failed due to tribofilm wear with DEVA 120, while TiAlN coatings failed from fatigue wear with DEVA 120 but succeeded with DEVA 121. Chrome-plated shafts experienced abrasive and adhesive wear with DEVA 121 but survived DEVA 120 due to transfer layer formation. The study highlights the need to understand wear mechanisms and material compatibility to develop durable coatings for harsh environments.

New insights into the corrosion mechanism of 316Ti austenitic steel exposed to 550 ℃ lead-bismuth eutectic with 5×10−6 wt% and 5×10−7 wt% oxygen concentration

The corrosion behavior of 316Ti steel in Lead-Bismuth Eutectic (LBE) was studied in this work. It reveals a transition in external oxidation between 5×10−6 wt% and 5×10−7 wt% DOC. The columnar magnetite (Fe3O4) formed under 5×10−6 wt% DOC grew via solid-state diffusion, while metal-dissolution/oxide-precipitation mechanism guided the external oxidation under 5×10−7 wt% DOC, forming equiaxed magnetite. Internal oxidation is influenced by the Ni-dissolution which facilitates the inner oxide growth. The internal oxide layer formed under 5×10−7 wt% DOC exhibit a better resistance to LBE penetration and oxide cracking. A corrosion model was proposed to elucidate the influence of DOC on the corrosion behavior of 316Ti steel.

Thermally-induced fracture in the oxide scale of T91 ferritic/martensitic steel after exposure to oxygen-saturated liquid lead–bismuth eutectic

Ensuring the continuity and stability of the oxide scale to separate T91 steel from lead-bismuth eutectic (LBE) is an effective method for limiting corrosion in the lead-based fast reactor system. In this study, we specifically investigated the impact of cooling thermal stress on the stability and damage of the oxide scales of T91 steel when exposed to oxygen-saturated liquid lead–bismuth eutectic at high temperatures. A corrosion test was conducted on T91 steels exposed to stagnant oxygen-saturated LBE at 500 °C. Experimental results indicated that oxide damage exists without any external force, including interface cracks and through-scale cracks perpendicular to the interface. We developed a three-layer peridynamic model of T91-(Fe,Cr)3O4-Fe3O4 to simulate the deformation and failure of oxides under a cooling process from high temperature to room temperature. The simulation results show that a temperature drop of about 200 °C from 500 °C can cause through-oxide cracks in the oxide scale, and subsequent cooling can lead to the propagation of interfacial cracks. Additional modifications were introduced in the model to account for the porosity of the oxide scale. Parametric investigations illustrate the effects of oxide scale thickness and porosity on the resulting crack patterns.

In-situ measurement of hydrogen isotope behavior in high temperature LBE: Diffusivity, permeability, and solubility

The Lead-Bismuth Fast Reactor (LBR) emerges as a promising concept due to its superior neutron economy, chemical stability, and thermal properties. From the nuclear safety standpoint, the focus has predominantly been on the behavior of 210Po and other fission products, while the issue of tritium in LBRs has not been sufficiently addressed due to the inconvenience of tritium experiments. Formation of tritium/helium bubbles induces significant local stress and volume expansion, leading to hardening and embrittlement of structural materials, thus expediting their degradation through irradiation effects. Current understanding of tritium transport within liquid Lead-Bismuth Eutectic (LBE) remains incomplete. To bridge this gap, a novel device employing the "permeation pot" method has been developed for the first experimental quantification of diffusivity, permeability, and solubility of hydrogen isotopes in liquid LBE. Notably, hydrogen diffusivity in this medium is found to be three to four orders of magnitude greater than in conventional 316L stainless steel structural material. Furthermore, the temperature-dependence of diffusivity in liquid metals is minimal compared to solids, as indicated by the activation energy. Conversely, solubility in 316L significantly surpasses that in LBE by three to four orders of magnitude. This discrepancy accelerates the tritium release from LBE to structural material, leading to the failure of the structural material.

Lazerckerite, Ag3.75Pb4.5(Sb7.75Bi4)S24, from Kutná Hora, Czech Republic: a new Sb–Bi member of the andorite branch of the lillianite homologous series

Abstract. Lazerckerite, ideally Ag3.75Pb4.5(Sb7.75Bi4)S24, is a new mineral species found in medieval mine dumps of the historic Ag–Pb–Zn Kutná Hora ore district, Czech Republic. The mineral is associated with other Sb–Bi lillianite homologues (terrywallaceite, gustavite, holubite) and Ag,Bi-bearing galena, most frequently as grain aggregates and replacement rims of earlier Ag–Pb–Bi minerals, growing together in aggregates of up to 0.6×0.3 mm. Lazerckerite is opaque, is steel grey in colour, and has a metallic lustre; the calculated density is 5.920 g cm−3. In reflected light lazerckerite is greyish white, and bireflectance and pleochroism are weak with grey tints. Anisotropy is weak to moderate with grey to bluish-grey rotation tints. Internal reflections are not observed. Electron microprobe analyses yielded the empirical formula, based on 44 apfu, (Ag3.61Cu0.04)Σ3.65(Pb4.55Fe0.01Cd0.01)Σ4.57(Sb7.87Bi3.75)Σ11.62(S24.15Se0.01)Σ24.16. Its unit cell parameters are a=13.2083(9), b=19.4595(8), c=8.4048(13), β=90.032(7)°, V=2160.3(4) Å3, space group P21/c, and Z=2. The structure of lazerckerite contains two Pb sites (Pb1 and Pb2) in bicapped trigonal prismatic coordination, 8 independent octahedral sites, and 13 distinct sulfur positions. Four of the octahedral sites are mixed (Sb,Bi) and (Bi,Sb) sites, one is a mixed (Ag,Bi) site, and one is a mixed (Sb,Pb) site. The new mineral belongs to the andorite branch of the lillianite homologous series with N=4 and is a new addition to the group of Sb–Bi mixed members of the series. Lazerckerite is defined as a lillianite homologue with the three following requirements: N=4, L (Ag++ (Bi3+, Sb3+) ↔ 2 Pb2+ substitution) ≈ 90 %–95 %, and approximately one-third of atom percentage of antimony is replaced by bismuth (Bi/(Bi+Sb) ≈ 0.30–0.38). The new mineral has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA 2022-113) and named after Lazarus Ercker, the supreme Royal Bergmeister of the Kingdom of Bohemia and the Master of Prague Mint.

Separate effect experimental test and theoretical investigate of pressure wave propagation and pressure rising process upon SGTR accident in advanced LFRs

Steam Generator Tube Rupture accident (SGTR) accident is one of the main safety events to the industrial application of Lead-cooled Fast Reactors (LFRs). This paper presents a separate effect test facility, called Lead-bismuth Eutectic Steam generator tube rupture Test facility (LEST), for testing high-pressure subcooled water jetting into a Lead Bismuth Eutectic (LBE) pool, and analyzes experimental data of maximum initial pressure peak, dynamic pressure attenuation together with the pressure rising process upon SGTR. The experimental analyses put forward a general equation form together with a dimensionless number of the initial pressure peak associated with a high-pressure Newtonian fluid injecting into another low-pressure Newtonian fluid, and the derivation of the general equation form is specifically applied to match a further semi-empirical equation for an initial maximum pressure peak with 5–10 MPa water injection in SGTR. The attenuation curve of dynamic pressure wave in each experiment is matched, and more weakening conditions can change the pressure peak from concentrated and non-period peak group to approximate period 1.4–3.7 s pulse group. The size relationship between pipe length L and nozzle diameter D, which L/D=12, is set to divide SGTR into small wall rupture and tube shear fracture, further three stages of pressure rising are distinguished in the tube shear fracture. This work provides experimental data to help determining the severity of SGTR and assessing the consequences of this event as part of the safety case for the industrial application of LFRs.

Numerical study on heat transfer characteristics of LBE cross flow tube bundle under rolling conditions

Combined with the neutron economy and good heat transfer performance, lead–bismuth fast reactor (LFR) has a larger prospect for marine applications. Helical coiled once-through tube steam generator (HCOTSG) is also a typical heat exchanger option for LFR. It is widely adopted in a variety of energy utilization fields, such as petrochemical industry. Study on Lead-bismuth eutectic (LBE) cross flow of tube bundle under moving conditions is necessary for obtaining the flow and heat transfer characteristics of LBE HCOTSG in marine conditions. A numerical method to simulate the heat transfer characteristic of LBE cross tube bundle flow under rolling conditions is proposed. The influence of the rolling conditions on the models with different tube arrangements are investigated. The temperature fluctuation curves with time and the time-averaged heat transfer characteristics are compared and analyzed. The results of the influence of rolling conditions under different working conditions and different tube bundle arrangements are obtained. The improvement ratio under inclined arrangement and staggered arrangement is more than 20 %, but the improvement under inline arrangement can only reach 10–15 %. Among the calculated models under different rolling conditions, the maximum heat transfer improvement reached 27.3 %. Besides, the circumferential temperature results under different conditions were also compared to analyze the influence of rolling conditions. This study may contribute to the application of LBE HCOTSG under marine conditions.