Lead-bismuth Eutectic Research Articles

Prediction of ‘effective’ corrosion rates by in-situ internal pressure creep testing in LBE for Ti-stabilised DIN 1.4970 (15-15Ti) austenitic stainless steel cladding tubes

ABSTRACT In this paper, a new high-temperature methodology for determining the ‘effective’ corrosion rates of internal pressure-tested cladding tubes, based on the reduced creep failure times under exposure, is presented. The methodology has been developed to estimate the combined damage accumulation of corrosion and creep and to establish temperature limits for the use of 1515Ti claddings in high-temperature Lead-Bismuth-Eutectic (LBE). The results are compared to static corrosion rates determined from earlier test campaigns in stagnant LBE. All tests are conducted on 24% cold worked 1515Ti cladding tubes that are the SCK CEN reference material for the MYRRHA design efforts. The virgin material creep model that is the basis for the corrosion rate estimation, has been fitted on an extended creep failure database and a life-fraction rule is applied to accommodate for the life reduction caused by the sought ‘constant’ effective corrosion rate.

Experimental and theoretical Ritz–Rydberg analysis of the electronic structure of highly charged ions of lead and bismuth by optical spectroscopy

Intra-configuration fine-structure transitions in highly charged ions (HCIs) result in most cases from changes in the coupling of equivalent electrons. They are multipole forbidden to varying degrees and often occur within the optical range. In HCI with semi-filled nd and nf subshells, electrons can in principle couple to states which are energetically close but with very different total angular momenta, e.g. 0⩽J⩽10 . This gives rise to metastable states with very long lifetimes that exhibit particularly interesting clock transitions or, as in the case of orbital level crossings, acquire a considerable sensitivity to a possible variation of the fine-structure constant α. We investigate both experimentally and theoretically connecting the ground state and adjacent states of Pb XXII to Pb XXXIV and Bi X to Bi XV, respectively, covering complex couplings of electrons in the 4f and 5d shells. These and others such as nd and nf , which also contain equivalent electrons, are of interest for frequency metrology using quantum logic spectroscopy, for atomic structure and QED theory tests, and for the search for Dark Matter candidates. We infer their level structure, benchmark calculations from two different electronic structure codes, and lay the groundwork for inferring the wavelengths of forbidden transitions of higher multipolarity in the optical and VUV region.

Study on Al2O3/Fe-Al gradient coating assisted prepared by ionic liquid for Lead-Bismuth eutectic corrosion resistance

Alumina coating which has excellent corrosion resistance to lead–bismuth eutectic (LBE) is very promising to be used in future LBE cooling system. In this paper, the Al2O3/Fe-Al gradient coating is prepared on the surface of SIMP steel assisted by ionic liquid aluminum electroplating and subsequent heat treatments and selective oxidation. The protective Al2O3 layer is composed of much γ-phase and a small amount α-phase. The Fe-Al transition layer is mainly composed of FeAl alloy phase. After being exposed for 600 h to LBE at 600 °C, the coating still maintains intact and dense structure and good compatibility to the substrate, effectively preventing the substrate steel from the corrosion attack of LBE. While obvious LBE attack can be observed in the compared bare steel. Finally, to verify the possibility of this approach preparing Al2O3/Fe-Al coating on complex geometries, we have also successfully prepared this sort of coating on the inner surface of a steel tube, indicating that this coating has a great application potential in the future.

Effect of Sputtering Bias Voltage on the Microstructure and Lead-Bismuth Eutectic Corrosion Resistance of the FeCrAlY Coating

FeCrAlY coatings deposited on the outer surface of the cladding tube by the magnetron sputtering with varying bias voltages (0 V to −500 V) were corroded at 550°C to 600°C in oxygen-saturated and oxygen-poor lead-bismuth eutectic for 500 h to 1,000 h. The increased bias voltage led to the Al content decreased and the Y content increased. The coating changed from columnar crystals to equiaxed crystals with increased bias voltage. The decreased bias voltage makes an improved corrosion resistance. The fundamental process governing the evolution of microstructure and corrosion resistance in the FeCrAlY coatings was discussed.

Lead-bismuth eutectic corrosion resistance of TiAlN coating after N5+ ion irradiation

In this study, a Ti0.33Al0.67N coating with Cr as the transition layer was prepared by cathodic arc-ion plating. After irradiation with N5+ ions, the coating was exposed to lead-bismuth eutectic (LBE) at 450 °C for 3000 h. The effect of irradiation on the corrosion resistance of the coatings was also investigated. No evidence of an LBE corrosion attack was observed in either the irradiated or unirradiated coatings. Transmission electron microscopy images revealed that the nanoscale oxide layer on the surface of the titanium aluminum nitride coating was the main barrier to LBE corrosion. The unirradiated coating had a single oxide layer, whereas the irradiated coating had a double oxide layer. Irradiation also affects the coating adhesion by inducing stress. However, after the corrosion test, the adhesion of all coating samples unexpectedly increased and were almost at the same level. The coating exhibited excellent properties after irradiation and LBE corrosion; therefore, the coating can be applied in future nuclear reactors.

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.

Numerical heat transfer to LBE flow in a wire-wrapped 19-rod bundle using an OpenFOAM-based solver: fourParameterFoam

The LBE-cooled fast reactor (LFR) has received significant attention due to its diverse applications. However, numerical heat transfer simulations encounter challenges with lead-bismuth eutectic (LBE) due to its low Prandtl number and high molecular thermal diffusion, often resulting in an overestimation of heat transfer using the simple gradient diffusion hypothesis (SGDH). This study aims to improve the prediction accuracy of heat transfer to LBE in numerical models by developing a solver, named fourParameterFoam, based on the turbulent model SST k-ω and algebraic heat flux model (AHFM) kθ-ɛθ within the OpenFOAM framework. The performance of SGDH models and AHFMs is compared based on heat transfer experiments in vertical tube flow with LBE. The behavior of the turbulent Prandtl number (Prt) under various flow conditions is concluded based on the SST k-ω-kθ-ɛθ model. Additionally, the applicability of the SST k-ω-kθ-ɛθ model in complex flow is validated through heat transfer experiments in a wire-wrapped 19-rod bundle with LBE flow. Local temperature variations on the heated rod surface and sub-channels are analyzed to elucidate the thermal development process in the bundle. The impact of wire spacers on flow behavior is summarized using visualization techniques, and the suitability of corresponding empirical Nusselt number correlations in LBE flow is evaluated.

Dissolution corrosion of FeCrAl alloy exposed to oxygen-depleted lead–bismuth eutectic containing Ni impurities at 600 ℃

FeCrAl alloy is one of the potential candidates of structural materials due to its high strength, low radiation swelling and good oxidation resistance for the application of lead-cooled fast reactors (LFRs). Particularly, FeCrAl alloy can form protective Al-containing oxide scales after exposure to liquid oxygen-rich Pb and lead–bismuth eutectic (LBE) at 400–800 ℃, showing better performance than traditional commercial stainless steels such as T91, 316L and 15-15Ti. Given the possibility that oxygen in liquid metal could be consumed and not be supplied timely in some quasi-static regions of the actual coolant circuit, to figure out the corrosion behavior of FeCrAl alloy in oxygen-depleted LBE is necessary. In this work, the commercial FeCrAl alloy was exposed to static liquid LBE containing Ni impurities with 10−9 wt% oxygen concentration at 600 ℃ for up to 5000 h, and the surface and cross-sectional morphology of the samples was characterized and analysed. It is found that FeCrAl alloy underwent severe dissolution corrosion, and the maximum penetration depth of LBE reached 161.4 μm after the test for 5000 h; PbBi infiltrated into alloy matrix along the GBs and selectively leached Al from the affected grains. Besides, an interesting discovery is the Cr-rich thin layer at LBE/matrix interface and Ni3Al precipitates in LBE penetration front which should be attributed to the deposition of impurity elements dissolved in liquid LBE during the cooling process.

Atomistic modelling of the Pb-Bi system from a constructed bond order potential

Lead-bismuth eutectic (LBE) alloys are currently considered one of the most promising liquid metal coolants for fast reactors, and especially accelerator-driven systems (ADS). An analytical bond-order potential (BOP) of Pb-Bi has been constructed to account for the electronic interactions and angular contribution of Pb-Bi system. The newly developed BOP has been validated to show a better performance than the Pb-Bi potentials already published in the literature. Molecular dynamics simulations based on current BOP has been adopted to investigate various properties of Pb-Bi binary system. It accurately predict the heats of formation, density, and thermal expansion coefficient of liquid LBE at 700 K. The diffusion coefficient and viscosity of liquid Pb44.5Bi55.5 are calculated, which are in good agreement with experimental observations in the literature. These findings provide a foundation for future design of Pb-Bi eutectic alloys for use in ADS and heavy-metal-cooled fast nuclear reactors.

Numerical study of solid-state oxygen control bypass performance and corrosion distribution in a LBE flow loop

Liquid lead–bismuth solid-state oxygen control technology is considered to be one of the effective means to inhibit corrosion of structural materials. The dissolution rate of PbO particles in the mass exchanger (MX) is a crucial factor influencing the effectiveness of solid-state oxygen control. To enhance the oxygen control efficiency of the MX, a PbO particle dissolution model based on the UPBEAT (Universal lead(Pb) bismuth(Bi) Eutectic Advanced Test loop) was established. This model aims to determine the impact of temperature, LBE flow rate, operating time, and initial oxygen concentration on the dissolution rate of PbO particles and the steady-state time in the MX. The obtained insights inform the design and operational aspects of the MX. Simultaneously, a loop corrosion precipitation model was developed to simulate loop corrosion in both oxygen-free and solid-state oxygen control states. While the corrosion precipitation distribution in the loop remains consistent between oxygen-free and oxygen-controlled states, solid-state oxygen control effectively enhances the corrosion resistance of the loop.

Design of control strategy for reactor power control system of LBE cooled Actinide Burner Reactor (ABR) using system analysis code NUSOL-LMR

The power control strategy for the Lead–Bismuth Eutectic (LBE) cooled Actinide Burner Reactor (ABR) has been designed to assess the closed-loop performance of newly developed control blocks that were not modeled in the NUSOL-LMR code before this research effort. After establishing a sustainable model of ABR in NUSOL-LMR, validation of the model in light of the already-published research is performed. The said closed-loop control strategy (consisting of the power and temperature control blocks) is evaluated under different transient scenarios (reactivity insertion, primary coolant pump fault, and change in demand power levels). The power and temperature control blocks concurrently control reactor power during any transient occurrence. The coupling effect of the primary coolant temperature deviation on the reactor power has been minimized by the proportional and integral (PI) controller in the temperature control block. The simulation results demonstrate that the closed-loop performance of the ABR under the controller action during transient events is quite satisfactory. The closed-loop power regulation performance of the conventional sliding mode controller (SMC) with a PI sliding surface (PISM) in the power control block of NUSOL-LMR is better than that of a simple proportional, integral and derivative (PID) controller. The asymptotic stability of the closed-loop system with the PISM controller has been ensured using the Lyapunov stability theory.

Direct Numerical Simulation of liquid metal forced and mixed convection in a square rod bundle

This paper reports results of Direct Numerical Simulations of fully developed, forced and mixed convection of Liquid Lead Bismuth Eutectic (LBE) around four vertical cylindrical rods arranged in a square lattice at Pr = 0.031. The solutions provided here are placed in a context where very few data are available for low-Prandtl flows, especially in mixed convection conditions, and can hence be useful for the development and validation of advanced turbulent heat transfer models. The equations are discretized using a Finite Volume implementation of a second order projection method. The irregular cylindrical boundaries are handled with an original Immersed Boundary technique. A single friction Reynolds number value is set (Reτ = 180) and buoyancy effects are accounted for by imposing the Rayleigh number, under the Boussinesq approximation. A Ra-value Ra = 2.5 ×104 is selected in order to investigate the main differences between forced and mixed convection at low Prandtl number values. Time-averaged velocity and temperature fields are shown, in order to discuss the main features of the flow and thermal fields. First order statistics are also presented, highlighting the effect of aiding buoyancy on turbulent heat and momentum transport.

Investigation on thermo-hydraulic characteristic of lead–bismuth eutectic and supercritical carbon dioxide in a straight-channel printed circuit heat exchanger

The Printed Circuit Heat Exchanger (PCHE) is considered a promising heat exchanger for Lead-Bismuth Eutectic (LBE) cooled fast reactors due to its superior pressure-bearing capacity and heat transfer efficiency. This paper introduces a conjugate heat transfer solver to investigate the thermo-hydraulic performance of a straight channel PCHE incorporating LBE and Supercritical CO2 (S-CO2). A four-equation model is implemented in the solver to capture the low Prandtl number turbulent heat transfer characteristics of LBE. Comparisons with LBE circular tube experimental results demonstrate that the solver presented enhances the resolution of LBE heat transfer simulations. This improvement in numerical resolution is crucial for understanding and predicting the behaviors of LBE-S-CO2 conjugate heat transfer process. Building on this, the present work explores the impacts of inlet mass flow rate, inlet temperature, S-CO2 pressure, and geometric parameters on the thermo-hydraulic performance of the straight channel PCHE. In terms of inlet temperature, quantitative analyses emphasize the effectiveness of augmenting the mass flow rate on the S-CO2 side to enhance overall heat transfer performance of PCHE. Adjusting the inlet temperature of S-CO2 or LBE to increase the temperature difference between the two fluids improves the average heat transfer rate, but reducing the S-CO2 inlet temperature may decrease the overall heat transfer coefficient. Furthermore, increasing S-CO2 pressure positively affects the thermal conductivity and specific heat capacity of S-CO2, thereby improving the thermo-hydraulic performance of PCHE. Additionally, geometric parameter sensitivity analyses indicate that decreasing wall thickness or increasing ridge width improves heat transfer, but increasing ridge width may significantly increase PCHE’s volume. The increased channel length results in a higher pressure drop, simultaneously enhancing heat transfer. From the Performance Evaluation Criteria (PEC) perspective, lengthening the channel is advantageous for the S-CO2 side but unfavorable for the LBE side. Regarding channel width, reducing channel width yields a larger increase in PEC on the S-CO2 side compared to the LBE side. Therefore, narrower flow channels on the S-CO2 side seem more advantageous. The present work provides a numerical tool with higher numerical resolution for studying LBE-S-CO2 conjugate heat transfer process and offers valuable insights for straight channel PCHE design.

Study on the corrosion behavior of laser surface remelted and laser cladding of ferritic/martensitic steels after exposure to lead-bismuth eutectic at 700 °C

This study explores two vital structural materials, T91 (Fe-9Cr) and SIMP (Fe-11Cr) steels, in the context of lead-cooled fast reactors and accelerator-driven sub-critical systems (ADS). Lead-bismuth eutectic (LBE) functions as a key coolant and spallation target material due to its impressive thermal conductivity, neutron yield, and chemical properties. Unfortunately, materials in contact with LBE are prone to severe corrosion at elevated temperatures (T>500 °C), compromising their integrity. To bolster corrosion resistance, we utilized laser remelting and laser cladding to apply FeCrAl/TiN coatings on the steel surfaces. Our study scrutinizes the corrosion behavior of steel in LBE saturated with oxygen at 700 °C and investigates the underlying causes. Following 240 h of exposure to corrosion, T91 and SIMP steels subjected to laser remelting displayed substantial oxide scale formation. Lead-bismuth atoms infiltrated the outer oxide layer (Fe3O4), diminishing adhesion between the inner and outer oxide layers, leading to the detachment of the outer oxide layer. The inner oxide layers, composed of Fe-Cr spinel, were approximately 123 μm thick for T91 steel and 77 μm for SIMP steel, underscoring SIMP steel's superior corrosion resistance. For T91 steel treated with laser cladding FeCrAl/TiN coating, a characteristic duplex oxide layer with a total thickness of around 83 μm was formed, with noticeable deposition of Pb-Bi atoms at the interface between the outer and inner oxide layers. Conversely, only a protective alumina layer safeguarded SIMP steel from LBE corrosion. This outcome emphasizes the efficacy of laser cladding FeCrAl/TiN coating in providing superior protection for SIMP steel over T91 steel. Our research significantly contributes to the development of anti-corrosion coatings for high-temperature LBE environments.

Neutronic evaluation for different external neutron sources in a Small-Subcritical fast reactor

This study proposes an optimized small-sized subcritical fast reactor with an external neutron source for actinide transmutation. The reactor integrates features of Accelerator Driven Systems (ADS) and Fusion-Fission Systems (FFS) based on Tokamak technology. Both external neutron sources were evaluated, one from fusion reactions and the other from spallation reactions in the designed small subcritical fast reactor. The analysis assessed neutron flux and actinide transmutation rates through fuel burnup simulations at 1200 K. The results underscore the significance of external neutron sources in subcritical systems, with the fusion-fission source presenting high actinide transmutation. The SSFR utilizes thorium oxide as fuel and Lead-Bismuth Eutectic (LBE) as coolant. Neutronic parameter comparisons between FFS and ADS neutron sources were conducted, showing advantages for actinide transmutation in the system with the FFS neutron source, which enhances transmutation, minimizing radiotoxicity. The neutronic parameters were obtained using the MCNP, while the MONTEBURNS code, which links the MCNP and the ORIGEN depletion code, was utilized to perform the fuel burnup simulations. The cross-section libraries were generated by the NJOY-2012 using the nuclear data library JEFF-3.3.

A novel monitoring system for fatigue crack length of compact tensile specimen in liquid lead-bismuth eutectic

Fatigue strength of the structural materials of lead-cooled fast reactors (LFRs) and accelerator-driven systems (ADS) may be degraded in liquid metal (Lead or lead-bismuth eutectic (LBE)) environments. The fatigue crack growth (FCG) data of structural materials in liquid LBE are necessary for damage tolerance design, safety assessment and life management of key equipment. A novel monitoring system for fatigue crack length was designed on the compliance method and the monitor technology of crack opening displacement (COD) of CT specimens by the linear variable differential transformers (LVDT) system. It can be used to predict the crack length by monitoring the COD of CT specimens in harsh high-temperature liquid LBE using a LVDT system. The prediction accuracy of this system was verified by FCG experiments in room temperature air and liquid LBE at 150, 250 and 350 °C. The first results obtained in the FCG test for T91 steel in liquid LBE at 350 °C are presented.

Thermal-hydraulic analysis of LBE flow in rod bundles with wire spacers based on heat transfer framework of OpenFOAM

The wire spacer allows for a compact layout in the core of lead-cooled fast reactor (LFR). However, it also introduces complexity to the flow and heat transfer of the coolant, lead-bismuth eutectic (LBE). This paper aims to analyze the effect of wire spacer in rod bundle and the applicability of heat transfer framework to LBE flow. Three Reynolds-Averaged Navier–Stokes (RANS) turbulence models with two representative turbulent Prandtl number (Prt) 1.5 and 2.0 are employed within the framework of OpenFOAM. The sensitivity of the models is examined based on turbulent heat transfer in tube flow. The simulations considered with an extensive mesh sensitivity study were analyzed. The buoyantSimpleFoam solver is compared with direct numerical simulation (DNS) data. Thermal-hydraulic analysis are conducted, considering temperature, velocity distribution, and local Nusselt (Nu) number, and pressure drop based on 7-rod and 19-rod bundle with wire spacers. The influence of wire initial starting angles from 0°, 10°, 20°, 30°, 40°, 50° on heat transfer is carried out. The study reveals that an optimum angle range from 20° to 40° exists in the sub-channels. This work validates the basic heat transfer solver for LBE using OpenFOAM.

Screening of Filler Material for a Packed‐Bed Thermocline Energy Storage Test Facility with Lead–Bismuth Eutectic as the Heat Transfer Fluid

Suitable solid filler materials are investigated for use in a packed‐bed heat storage test facility for high temperatures with lead–bismuth eutectic (LBE) as the heat transfer fluid. Accordingly, first, the thermophysical properties of six different candidate materials, two glasses and four ceramics, are determined. The density and heat capacity are measured experimentally and the thermal conductivity is discussed based on literature data. Subsequently, a static corrosion test is performed at 500 °C for 1 and 4 weeks in LBE under reducing conditions. The glasses are found to be unsuitable due to corrosion attack. Among the ceramics, zirconium silicate and zirconium oxide are identified to be highly resistant to corrosion. Zirconium silicate is subsequently also successfully tested as a storage material in a laboratory experiment under cyclic conditions.

Superior corrosion resistance of a slurry FeAl coating on 316LN stainless steel in 550 ℃ liquid lead-bismuth eutectic

An intermetallic Fe-Al coating was successfully produced on 316LN austenite stainless steel by slurry Aluminizing. The coating greatly enhanced the corrosion resistance of substrate in LBE (lead-bismuth eutectic) containing low (10−7 wt%) and high (1.8 ×10−3 wt%) oxygen concentrations at 550 ℃ and the coating was mostly intact after 1500 h exposure test. The high corrosion resistance results from the formation of a uniform layer of alumina oxide on the coating which can be achieved when the dissolved oxygen is above 10−18 wt%. This FeAl coating maybe a promising option for protecting structure material in the fourth LBE-cooled fast reactor.

Electrochemical and metallographic characterization of Ni-NiO-NiBi3 equilibrium in molten lead-bismuth eutectic

This study aims to investigate the chemistry of the Ni-O-Pb-Bi system through a combined microscopic and electrochemical analysis of the Ni-NiO-NiBi3 equilibrium in molten lead-bismuth eutectic (LBE). Through SEM-EDX metallographic characterization, we examined to the precipitates formed on the solid nickel substrate in molten LBE, confirming the formation of the NiBi3 within the temperature range of 469–748 K. Subsequently, we induced the Ni(LBE)-NiO(s)-NiBi3(s) ternary equilibrium in LBE and measured the equilibrium oxygen concentrations at different temperatures. The equilibrium nickel activity was derived using the measured equilibrium oxygen concentration in the temperature range of 518–595 K. Finally, the Ni-Bi IMCs floating on LBE at the end of the measurements were collected and characterized by X-ray diffraction (XRD), confirming the presence of the NiBi3 phase.