Coolant Velocity Research Articles

A coupled thermohydraulic/neutronic investigation of noise propagation in VVER-1000 reactor using[formula omitted] nanofluid coolant

Thermohydraulic and neutronic coupling for the VVER-1000 reactor carried out by applying Al2O3 nanofluid as coolant in this paper. The simulation took place in two sections; with the neutronic section, the discretization of the nodal (average current) method for dissociation of two-group diffusion equations accomplished and with the thermohydraulic section, the finite volume method for decomposition of conservation equations (mass, momentum and energy) in static and transient states was used.In this study, neutronic and thermohydraulic noises (Fourier transform) in the frequency domain were analyzed by applying propagation noise sources in the VVER-1000 reactor core. With the neutronic section, macroscopic cross sections were generated making use of Al2O3 nanofluid as coolant with different volume fractions by means of WIMS-D5 computation code.The ultimate goal of the paper is to perform neutronic and thermohydraulic simulations of VVER-1000 reactor using Al2O3 nanofluid as coolant in the frequency domain. Two separate noise scenarios for the inlet nanofluid coolant (coolant temperature and velocity) with different volume fractions of Al2O3 nanoparticles (0.001%, 0.1% and 1.0%) were considered in the analysis. Final results showed that the core power peaking factors will be less influenced by inlet fluctuations when applying more nanoparticles in the reactor coolant.

Combined Numerical and Experimental Investigations into the Local Fluid Dynamics of Coolant Flow in the Mixed Core of a VVER Reactor

The article presents the results from experimental investigations into local coolant flow fluid dynamics that were carried out on the fragmental model of a VVER-type pressurized water reactor’s mixed core consisting of two types of fuel assemblies (FAs): TVSA-T (one segment) and TVSA-T.mod.2 (two segments). The coolant flow processes in the fuel rod bundle were simulated on an aerodynamic test bench. The pressure field in the flow was measured using a five-channel pneumometric probe. The obtained pressure field in the flow was recalculated for the coolant velocity vector according to the dependences derived during calibration. For drawing up a detailed flow motion pattern, a characteristic model cross section area was separated, which included the space between the assemblies and four fuel rod rows in each TVSA-type fuel assembly. The spatial distribution of coolant flow velocity projections was analyzed, as a result of which it became possible to reveal the regularities associated with the streamlining of spacer-, mixing-, and combined-spacer grids in TVSA assemblies by coolant; to determine coolant cross flows resulting from streamlining of hydraulically nonidentical grids and determine their localization in the experimental model longitudinal and cross sections; and to reveal the effect of accumulating flow hydrodynamic disturbances in the model longitudinal and cross sections resulting from the staggered arrangement of hydraulically nonidentical grids. The results obtained from investigations of inter-assembly interaction of coolant between the neighboring TVSA-T and TVSA-T.mod.2 assemblies have been adopted for practical use at AO Afrikantov OKBM in estimating the thermal reliability of VVER-type reactor cores and have been included in the database for verification of computation fluid dynamics computer programs (CFD codes) and detailed cell-wise numerical analysis of the core of VVER reactors.

Numerical analysis on thermal–hydraulic performances of staggered tube bundles for an aero-engine compact precooler

The deeply precooled air-breathing technique is an effective approach to cool down the extreme hot incoming air for hypersonic engine. This paper investigates the thermal performance of staggered mini-tube bundle as the compact precooler for aero-engine application. The coupling heat exchange between the hot air and in-tube coolant is explored. Two methods (i.e., surface temperature method and LMTD method) are used to evaluate the airside heat transfer characteristics. Comparison of predicted Nusselt number and empirical correlations shows that both methods have acceptable discrepancies, especially for surface temperature method. In addition, Nusselt number predicted by the surface temperature method almost keeps identical at different coolant velocities, while the LMTD method is sensitive to the flow velocity of in-tube coolant. In order to better understand the influences of boundary conditions, the detailed analysis for parameters such as inlet pressure, inlet temperature, transverse pitch, coolant velocity and property variation on thermal performance of the tube bundle is carried out.

Investigation of Coolant Local Hydrodynamics in the Mixed Core of the VVER Reactor

The article presents the results of experimental studies of the local hydrodynamics of the coolant flow in the mixed core of the VVER reactor, consisting of the TVSA-T and TVSA-T mod.2 fuel assemblies. Modeling of the flow of the coolant flow in the fuel rod bundle was carried out on an aerodynamic test stand. The research was carried out on a model of a fragment of a mixed core of a VVER reactor consisting of one TVSA-T segment and two segments of the TVSA-T.mod2. The flow pressure fields were measured with a five-channel pneumometric probe. The flow pressure field was converted to the direction and value of the coolant velocity vector according to the dependencies obtained during calibration. To obtain a detailed data of the flow, a characteristic cross-section area of the model was selected, including the space cross flow between fuel assemblies and four rows of fuel rods of each of the TVSA fuel assemblies. In the framework of this study the analysis of the spatial distribution of the projections of the velocity of the coolant flow was fulfilled that has made it possible to pinpoint regularities that are intrinsic to the coolant flowing around spacing, mixing and combined spacing grates of the TVSA. Also, the values of the transverse flow of the coolant caused by the flow along hydraulically nonidentical grates were determined and their localization in the longitudinal and cross sections of the experimental model was revealed. Besides, the effect of accumulation of hydrodynamic flow disturbances in the longitudinal and cross sections of the model caused by the staggered arrangement of hydraulically non-identical grates was determined. The results of the study of the coolant cross flow between fuel assemblies interaction, i.e. between the adjacent TVSA-T and TVSA-T mod.2 fuel assemblies were adopted for practical use in the JSC of “Afrikantov OKB Mechanical Engineering” for assessing the heat engineering reliability of VVER reactor cores; also, they were included in the database for verification of computational hydrodynamics programs (CFD codes) and for detailed cell-based calculation of the reactor core.

The effect of pulsating parameters on the spatiotemporal variation of flow and heat transfer characteristics in a ribbed channel of a gas turbine blade with the pulsating inlet flow

This paper presents an investigation on the cooling performance in a ribbed channel with the pulsating inlet flow. The flow structures and heat transfer characteristics are simulated by solving the three-dimensional Unsteady Reynolds-Averaged Navier-Stokes equations (U-RANS) and the Shear Stress Transport (SST) turbulence model coupled with the γ-Reθ transition. The influence of pulsating parameters in terms of pulsating amplitudes and frequencies on the cooling performance are evaluated at the Reynold number of 10000. The results obtained show that the coolant velocity variation corresponds to the inlet velocity variation, almost the sinusoidal curve shape. The heat transfer performance influenced by the turbulence intensity is also the sinusoidal curve shape and increases with increasing pulsating amplitudes and frequencies. The pressure loss penalty related to the flow characteristics is also the sinusoidal curve shape while the thermal performance indexes at four time frames (1T/4, 2T/4, 3T/4 and 4T/4) show the 90-degree phase difference with the sinusoidal curve. Additionally, the thermal performance increases with increasing pulsating amplitudes and frequencies.

Power upgrading of WWR-S research reactor using plate-type fuel elements part I: Steady-state thermal-hydraulic analysis (forced convection cooling mode)

The design of a nuclear reactor core requires basic thermal-hydraulic information concerning the heat transfer regime at which onset of nucleate boiling (ONB) will occur, the pressure drop and flow rate through the reactor core, the temperature and power distributions in the reactor core, the departure from nucleate boiling (DNB), the condition for onset of flow instability (OFI), in addition to, the critical velocity beyond which the fuel elements will collapse. These values depend on coolant velocity, fuel element geometry, inlet temperature, flow direction and water column above the top of the reactor core. Enough safety margins to ONB, DNB and OFI must-emphasized. A heat transfer package is used for calculating convection heat transfer coefficient in single phase turbulent, transition and laminar regimes. The main objective of this paper is to study the possibility of power upgrading of WWR-S research reactor from 2 to 10 MWth. This study presents a one-dimensional mathematical model (axial direction) for steady-state thermal-hydraulic design and analysis of the upgraded WWR-S reactor in which two types of plate fuel elements are employed. FOR-CONV computer program is developed for the needs of the power upgrading of WWR-S reactor up to 10 MWth.

The Effect of Coolant Velocity for Enhancing the High-Speed Permanent Magnet Generator Efficiency

Abstract A High-Speed Permanent Magnet (HSPM) generator was designed and developed to deliver 10 kW output power at a speed of 30000 RPM. However, achieving a compact and efficient design with lower excitation losses, magnetizing currents and rotor losses remains as a daunting challenge. At high speeds these machines produce a substantial amount of heat which makes the thermal management of these machines difficult and complicated. This paper presents the design and development of the HSPM generator. The development of an adequate cooling system (cooling jacket) is also presented and enables the control of the temperature rise of the generator. A 3D steady state model of a 10-kW electric permanent magnet machine was generated and investigated with a cooling jacket layout. The numerical simulations on the effect of coolant flowrate for enhancing the HSPM generator efficiency was performed using ANSYS Fluent. Numerical analysis was performed with two different coolant flow rates, no flow and maximum flow (3.5 m3/h) with special emphasis on the maximum motor temperature. Maximum coolant flowrate conditions showed lower temperature generation throughout the generator compared to no coolant flowrate through the cooling jackets. The lower temperatures achieved, ensure that the magnets, winding insulation, and bearings are not affected by the heat generated.

The influence of coolant velocity on the local heat transfer coefficient during steel quenching

The influence of coolant velocity on the local heat transfer coefficient during steel quenching

A novel battery thermal management system coupling with PCM and optimized controllable liquid cooling for different ambient temperatures

In order to improve the working performance of the lithium-ion battery pack in continuous operation under different ambient temperatures, a coupled composite phase change material and liquid cooling thermal management system is proposed. The simulation for this system under a cycle that a 3C rate discharging and then a 0.5C charging was conducted, as well as comparison tests concerning factors such as cell-to-cell spacing, cell-to-tube distance, channel number and coolant velocity. Simulation results showed that the coupled system with suitable design exhibited good thermal performance at an ambient temperature of 30 °C, which kept the maximum surface temperature and the temperature difference of the battery pack at 41.1 °C and 4 °C at the end of 3C discharge. Then, the latent heat of phase change material was also recovered by the liquid cooling during the 0.5C charge. Specially designed experiments have also been conducted to verify the effectiveness and practicability of the proposed coupled system. Based on this system, a liquid cooling strategy was proposed for controlling the velocity and inlet temperature of coolant by monitoring the temperature of the phase change material and environment. This further improved the thermal performance of the battery pack during cycling at different ambient temperatures and significantly reduced the unnecessary power consumption of liquid cooling during this process.

The Dynamic-Implicit-Additional-Source (DIAS) method for multi-scale coupling of thermal-hydraulic codes to enhance the prediction of mass and heat transfer in the nuclear reactor pressure VESSEL

The paper describes a Dynamic-Implicit-Additional-Source (DIAS) method for a domain-overlapped multi-scale coupling of a system-code, sub-channel code, and CFD code aiming to improve the simulation of the thermal-hydraulics phenomena e.g. the heat, mass, solute transfer in the Nuclear Reactor Pressure Vessel (RPV). This method is developed to correlate the essential physical parameters predicted by the nuclear system thermal-hydraulic code with more precise data derived from sub-channel or Computational Fluid Dynamic (CFD) solutions, enabling the system-code to produce more realistic mass and heat transfer within the RPV. The DIAS-method is used in combination with the domain-overlapping coupling approach and it currently correlates four system-codes parameters: the coolant velocity, the pressure drop, the coolant temperature, and the boron concentration.The three-dimensional velocity and pressure fields predicted by a sub-channel or CFD codes are used to calculate the new friction and form loss coefficients on the fly (in the momentum equation) at all the overlapped edges in the system-code with increased accuracy. Additionally, the coolant temperature distribution predicted by the system-code is correlated based on the three-dimensional temperature field gained from the sub-channel or CFD codes by adding a dynamic-implicit heat source or sink to the energy equation. Such kind of source/sink was also added to the solubility equation of the system-code to predict the boron concentration based on the corresponding high-resolution fields provided by the high-resolution thermal-hydraulic solvers. All of the three newly added items are named as the Dynamic-Implicit-Additional-Source (DIAS) since they are not the traditional fixed-explicit appendixes to the original system of governing equation set but they are dynamically tuned and implicitly calculated along with the solution process.The complete DIAS-method was verified with an academic 3D coolant-mixing problem in a Reactor Pressure Vessel (RPV). Results obtained from the test cases indicate that the mass, heat and solute transfer in the RPV could be better predicted by the coupled codes with the DIAS method. Finally, the DIAS method is proved an efficient and powerful approach for multi-scale thermal-hydraulic coupling based on the domain-overlapping approach.

Film boiling collapse in a solid hot sphere immersed in subcooled forced convection

An experimental study of forced convection film boiling was conducted, on a stainless steel sphere with diameter of 30 mm with different coolant velocities. A visualization research on the motion of the vapor/liquid interface and the rupture process has revealed a detailed mode for vapor film rupture, which relates to the motion of a wetting boundary on the hot surface of a sphere. The rupture sequence of the vapor film on different monitor points in the sphere was obtained by the analysis of surface temperatures and heat fluxes during the process. In addition, the influence factors of vapor film rupture were also studied. It is concluded that, in forced convection, the rupture process of vapor film on the surface of the sphere is affected by the temperature distribution of the sphere; liquid flow velocity, cooling effect of the cylindrical support pipe and liquid subcooling degree also have significant impacts on it.

Method for selecting geothermal energy extraction technologies using nomograms

The article analyzes the efficiency of geothermal energy extraction method. Different regions of the Russian Federation were analyzed. Available geothermal energy extraction technologies using nomograms were analyzed. The nomograms describe the dynamics of outlet changes in temperatures and the amount of energy produced at various coefficients of thermal conductivity and heat capacity of rocks. The nomograms used for selection of suitable geothermal energy production technologies depending on geological and physical conditions were developed. Based on geological and physical characteristics of the bottomhole formation zone, such well parameters as the radii of the casing and the tubing and coolant velocity, outlet temperatures and thermal capacity of the well were calculated. The more efficient technology was selected.

Designing of cooling water system for a pyro-breaker utilized in superconductive fusion facility

Pyro-breaker used as a backup breaker in Quench Protection System (QPS) guarantees the safety of a superconductive fusion facility. High current flows through the pyro-breaker and great amount of heat flux will be brought into the breaker due to the structure and mechanism of the Pyro-breaker. Requirement of each subsystem is crucial for the overall designing of the entire Cooling Water System (CWS). In this paper an optimized design of the CWS for Pyro-breaker is presented. Theoretical calculation and Computational Fluid Dynamics (CFD) are used to analysis the heat transfer coefficient of the cooling system. Thermal-electrical simulation is performed on the model and the result is verified by experiment on a prototype. It can be concluded that the presented Pyro-breaker model has the current capacity of 40kA with the coolant velocity of 1 m/s. Optimization of the CWS is made based on the verified method and a set of required coolant velocities is proposed when the current capacity reaches up to 80kA. The pressure drop, which is an important factor for the entire CWS, is calculated in ANSYS CFX when the breaker is applied under 80kA.

Design of Two Experimental Mock-Ups as Proof-of-Concept and Validation Test Rigs for the Enhanced EU DEMO HCPB Blanket

Within the framework of EUROfusion activities, the helium cooled pebble bed (HCPB) breeding blanket is under development in Karlsruhe Institute of Technology (KIT). The enhanced HCPB, using a fissionlike fuel breeder pin assembly configuration, is proposed as the near-term breeding blanket for the European Union DEMOnstration power plant (EU DEMO). The helium gas with a pressure of 8 MPa is used as the coolant, EUROFER is used as the structural material, advanced ceramic breeder pebbles are used as the tritium breeder, and Be12Ti is used as the neutron multiplier material. In contrast to the former HCPB cooling plate configuration, the fuel breeder pin assemblies greatly reduce the pressure drop, reducing the circulating power to the level where state-of-the-art helium turbomachinery can be used. However, because of the reduced coolant velocity in the breeder zone, the heat transfer performance is compromised, especially in the annular channel of the fuel breeder pins. An increased surface roughness is therefore proposed as a heat transfer augmentation technique for the fuel breeder pins. Although heat transfer augmentation using artificial roughness is common, it is relatively novel for small annular gaps with moderate velocity as the ones in the fuel breeder pins. Currently, a dedicated correlation for the small annular rough-wall channel is available to predict the Nu number. This correlation is wished here to be benchmarked and validated experimentally. Therefore, an experimental investigation on a fuel breeder pin mock-up (mock-up 1) is planned. Additionally, based on computational fluid dynamics calculation, unsteady, nonuniform flow patterns were found at the return flow after the jet impingement in the first-wall region. Another upscaled mock-up (mock-up 2) to investigate the nonuniform flow patterns of the return flow in the annular channel of the fuel breeder pin is planned. The dedicated experimental campaigns are foreseen at the Helium Loop Karlsruhe (HELOKA) in KIT as validation and proof-of-concept test rigs for this enhanced pin design. In this paper, the motivation and the preliminary design of these two mock-ups of the enhanced EU DEMO HCPB blanket are shown, together with the plan for the foreseen experiments.

Modelling mass and heat transfers of Permeate Gap Membrane Distillation using hollow fibre membrane

In this study, a set of mathematical models was used to simulate the heat and mass transfers of hollow fibre PGMD module for desalination applications. The developed model was firstly validated, and then utilized to study the impacts of different design parameters and operating conditions on the performance of hollow fibre PGMD. The simulation results show that coolant velocity and coolant temperature have less impacts on flux compared to those in DCMD, because in DCMD, coolant directly contacts the membrane but for PGMD it does not. The model also demonstrates that the higher cooling plate thermal conductivity will lead to higher flux and energy efficiency. However, when the cooling plate thermal conductivity is higher than 5 W/m.K, the temperature difference across the cooling plate is minimum and further increase of the cooling plate thermal conductivity has negligible impacts on flux and energy efficiency. A sensitivity analysis was undertaken to analyze the combined effects of gap channel inner/outer diameters and gap channel thermal conductivity on flux. It is concluded that the changes in gap channel of hollow fibre PGMD will lead to a more complex combination, and the gap channel thermal conductivity has a more significant effect on flux compared to the hydrodynamics within the permeate and coolant channels. The effect of multi-stage processes on energy efficiency is also evaluated. The results suggest that Gain Output Ratio (GOR) increases with number of stages, and reaches 2.4 with 20 stages. Finally, the roles of different parameters in PGMD optimization are discussed. The results suggest that cooling plate thermal conductivity plays the most important role in PGMD optimization compared to coolant velocity and coolant inlet temperature.

Investigation on cooling performance of WCLL breeding blanket first wall for EU DEMO

The Breeding Blanket (BB) First Wall (FW) is the first boundary separating the fusion plasma and its energetic particles from the rest of a Tokamak. The heat load specifications at different poloidal positions are reviewed according to the maximum heat load (surface radiation and charged particles). In the framework of the European Demonstration (EU DEMO) fusion reactor work package for BB, the cooling performance of the Water-Cooled Lithium Lead (WCLL) BB FW is investigated using a Computational Fluid Dynamics (CFD) approach. The reference geometry is compared with different FW geometries and cooling schemes. The configuration with two passes has better cooling performance and the coolant velocity is lower than the limit (i.e., 7 m/s). Compared with the square channels, the circular design highlighted a higher temperature hot-spot in the structural material. Under the non uniform heat flux (HF) distribution, the structure temperature exceeds the upper limits at the FW elbows of the Inboard Blanket (IB) 5, 6,7, plus the upper part of IB4, where the HF is beyond 1.34 MW/m2. The current WCLL FW design is far away from the occurrence of Departure from Nucleate Boiling (DNB). In general, the present design of the FW can maintain the temperature of the structure below the limit and ensure the design coolant temperature at the channel outlet (i.e., 328 °C).

Preliminary Experiment of U-Shaped Heat Pipe as Passive Cooling System in High Temperature Gas-Cooled Reactor Cooling Tank

When station blackout occurs on high temperature gas-cooled reactor, the decay heat will be absorbed by a residual heat dissipation system (known as cooling tank) which connected to the reactor cavity cooling system. The U-shaped heat pipe as passive cooling system is proposed as new feature of technology to absorb the decay heat in the high temperature gas-cooled reactor cooling tank, and to keep the water remains in its operating temperature and level. This research objective is to know thermal resistance of U-shaped heat pipe scale model based on variation of heat load and coolant velocity. The influence of water temperature in the circulating thermostatic bath as heat load on evaporator section and air velocity which flowed into the horizontal condenser fin were investigated experimentally. The heat loads were varied at water temperature of 45, 50, and 60°C. The air velocities were varied at 0.45, 0.83, and 1.06 m/s. The experiment result showed the lowest thermal resistance of 0.000027±0.0000000593 °C/W when U-shaped heat pipe was operated at hot water temperature of 60°C and air velocity of 1.06 m/s. The investigation result can be used as a model and initial knowledge to design large scale of U-shaped heat pipe as a passive cooling system in cooling tanks connected to high temperature gas-cooled reactor cavity cooling system. This result is also useful regarding to the thermal management of passive cooling process in cooling tank and it can improve the nuclear safety and be able to overcome the thermal problems caused by station blackout in high temperature gas-cooled reactor.

Numerical Simulation of Thermal–Hydraulic Processes in Liquid-Metal Cooled Fuel Assemblies in the Anisotropic Porous Body Approximation

The article presents an anisotropic porous body model in which the transfer anisotropy is taken into account through determining—by means of tensor analysis techniques—the drag force, effective viscosity, and thermal conductivity. The model is intended for describing heat-and-mass transfer in fuel assemblies and tube bundles. For closing the system of anisotropic porous body equations, the integral turbulence model developed by the authors is used. To verify how correctly the hydrodynamics and heat transfer are described, a few hydrodynamic and thermal–hydraulic processes in water- and liquid-metal-cooled fuel rod assemblies are simulated in the anisotropic porous body approximation. The results from simulating the flow patterns of lead–bismuth eutectics in the experimental 19-rod assembly and water in a 61-rod nonheated assembly with its flow cross-section locally blocked in the central and corner parts are presented. The thermal–hydraulic processes in the BREST reactor fuel assembly’s heated 19-rod fragment with its flow cross-section locally blocked in the central part were also simulated using the CONV-3D DNS code in the framework of model cross-verification activities. The numerical analysis was carried out using the developed APMod software module implementing the anisotropic porous body model jointly with the integral turbulence model. It was demonstrated from a comparison of the numerical analysis results with both experimental data and simulation results obtained using the CONV-3D computer code that the APMod software module adequately describes the 3D fields of coolant velocities, pressure, and temperature arising in fuel rod assemblies with a locally blocked part of their flow section. The obtained results testify that the anisotropic porous body model can be used for simulating thermal–hydraulic processes in the cores and heat-transfer equipment of prospective reactors.

ЭКСПЕРИМЕНТАЛЬНОЕ МОДЕЛИРОВАНИЕ ПРОЦЕССОВ ГИДРОДИНАМИКИ И ТЕПЛООБМЕНА В РЕАКТОРАХ С ТЯЖЕЛЫМИ ЖИДКОМЕТАЛЛИЧЕСКИМИ ТЕПЛОНОСИТЕЛЯМИ

The similarity analysis and the following criteria as well asymptotic solutions must be fully applied at planning and carry out the experimental study and generalizing its results. As academician S.S. Kutateladze notes "The external simplicity of the foundations of this analysis and the everincreasing multi-parametric nature of the problems for physical and mathematical modeling lead to many misunderstandings and direct mistakes”. Liquid metals form a special class of coolants characterized by a significant volumetric heat capacity and high thermal conductivity, which have the coefficient of kinematic viscosity much lower than the coefficient of thermal diffusivity, its Prandtl number is much less than one. The analysis results of the application of the similarity theory of the thermophysical processes to the modeling of hydrodynamics and heat transfer in liquid metals are presented in this report for: channels of complex shape, rod systems (reactor core and heat exchangers), temperature fields and coolant velocity in a hot chamber of a fast reactor in different operating modes. Practically the direct modeling can be applied unlimitedly only for processes in which determined similarity numbers are functions of only geometric simplices of the system and one defining criterion. For example the presence of two defining criteria such as the numbers Re and Pr during heat exchange makes modeling much more difficult. With three defining criteria the direct modeling is usually not feasible. In such cases it is necessary to caring out the systematic multivariate experiments. The purpose of such modeling experiments is the real detection of effects solved by a very general mathematical model but not impossible to carry out at the modern level of mathematical technologies, either analytically or in numerical studies.

ВЛИЯНИЕ ПУЗЫРЬКОВ ГАЗА НА ЭРОЗИЮ СТАЛИ В СВИНЦЕ

The erosion of the steel surface in lead-based coolants is a powerful factor that initiates corrosion of the structural material. In the conditions of cavitation effect of gas bubbles on the oxide coating, breaches of its integrity can be created, as a result of which an intensive influence of lead on steel occurs on the "bare" areas. This leads to a multiple increase in the rate of corrosion. The regularities of erosive action of lead or its alloys on structural materials have not been sufficiently studied. In the experiments of different authors, differing data of flow rates of lead or lead-bismuth, to cause the erosion of steel, were obtained. In general, this phenomenon is a combination of a number of simultane-ously occurring thermohydraulic and physicochemical processes. Erosion failure of structural materials in a heavy coolant is rapidly developing and occurs in places with increased coolant velocities, in the field of hydrodynamic disturbances, and so on. Protective coatings formed on steels based on oxide technology are vulnerable from the point of view of erosion wear. The erosion of protective coatings on steels can in turn cause peeling of fuel rod cladding with end-to-end sheath breaking, which can proceed more intensively than the front dissolution of unprotected shells.The most significant factor leading to the erosion of steel in lead is the hydrodynamic effect of the coolant flow. In the presence of gas bubbles in the coolant, erosion occurs at the lowest flow rates, and the erosive effect itself has a cavitation character. The present report presents the results of studies of erosion of steel in lead under gas cavitation. A methodology for appropriate erosion testing was developed. Experiments were carried out on the installation with a rotating cylinder at different cylinder speeds and at various temperatures. A numerical solution of the differential equation of motion of the bubble wall is performed for the different hydrodynamic parameters of the lead flow. The experimental and calculated data obtained make it possible to estimate the process parameters under which a cavitation damage of the oxide coating occurs on the steel surface in the flowing lead.