Modeling of Thermohydraulics in a Lead-Cooled Reactor System - A CFD Study Using OpenFOAM
(2026) MVKM01 20261Department of Energy Sciences
- Abstract
- This study investigates the thermal-hydraulics of a simplified model of Blykalla's Swedish Advanced Lead-cooled Reactor (SEALER) using computational fluid dynamics (CFD) in OpenFOAM. The objective is to develop and verify a system-level model for forced and natural convection. The reactor cooling circuit is represented using porous media and volumetric source terms. Simulations are conducted using Reynolds-averaged Navier-Stokes (RANS), employing both eddy-viscosity and Reynolds stress turbulence models. The model is initially validated for single-phase steady-state forced convection by comparison with reference data. Strong agreement is obtained with respect to mass flow rate, core temperature difference, and pressure drop, indicating a... (More)
- This study investigates the thermal-hydraulics of a simplified model of Blykalla's Swedish Advanced Lead-cooled Reactor (SEALER) using computational fluid dynamics (CFD) in OpenFOAM. The objective is to develop and verify a system-level model for forced and natural convection. The reactor cooling circuit is represented using porous media and volumetric source terms. Simulations are conducted using Reynolds-averaged Navier-Stokes (RANS), employing both eddy-viscosity and Reynolds stress turbulence models. The model is initially validated for single-phase steady-state forced convection by comparison with reference data. Strong agreement is obtained with respect to mass flow rate, core temperature difference, and pressure drop, indicating a consistent implementation of the system components. A noticeable deviation of \SI{18.6}{\%} is observed in the steam generator pressure drop, which suggests sensitivity to the porous media implementation. The turbulence model has a negligible impact on system-level performance during forced convection. For natural convection, the results show a strong dependence on reactor geometry, where increased system height enhances circulation and thermal distribution. The choice of turbulence model has a more pronounced effect under natural convection conditions, where the Reynolds stress model predicts a lower mass flow rate and exhibits reduced numerical stability compared to the eddy-viscosity models. The influence of thermophysical modeling is assessed by comparing a temperature-dependent property model with the Boussinesq approximation. The Boussinesq model predicts a higher mass flow rate and a lower temperature rise across the core, consistent with its simplified treatment of density variations. Multiphase simulations using a volume of fluid (VOF) approach are conducted to assess the capability to predict buoyancy-driven flow in the presence of large density differences. The results indicate that the presence of a gas phase has a negligible impact on system performance and that the OpenFOAM treatment of buoyancy is sufficient for system-level analysis. (Less)
- Popular Abstract
- Understanding Nuclear Reactor Cooling with Computer Simulations
How well can computer simulations predict the cooling of a nuclear reactor without pumps? The safety of next-generation reactors depends on removing heat even during failures, making reliable predictions of reactor cooling essential. This study uses computer simulations to investigate how a simplified lead-cooled reactor system can be modeled.
In this study, such a system is modeled using OpenFOAM, which is an open-source computational fluid dynamics (CFD) software. In addition to simulating the system, the study evaluates the model's ability to predict system performance and its limitations. This is achieved by comparing key quantities such as flow rates, temperature... (More) - Understanding Nuclear Reactor Cooling with Computer Simulations
How well can computer simulations predict the cooling of a nuclear reactor without pumps? The safety of next-generation reactors depends on removing heat even during failures, making reliable predictions of reactor cooling essential. This study uses computer simulations to investigate how a simplified lead-cooled reactor system can be modeled.
In this study, such a system is modeled using OpenFOAM, which is an open-source computational fluid dynamics (CFD) software. In addition to simulating the system, the study evaluates the model's ability to predict system performance and its limitations. This is achieved by comparing key quantities such as flow rates, temperature differences, and pressure drops to reference data.
The model is also used to investigate performance during natural circulation. Here, the analysis is based on qualitative comparisons and observed trends when geometry and modeling approaches are varied. The results are also used to evaluate how the model predicts natural circulation when a gas layer is present above the circulating lead.
The simulations show that the model can successfully predict how heat is removed from the reactor system. By comparing the key quantities to reference data, it is determined that the model is able to capture the most important physical processes.
When the pumps and active cooling system are turned off, the reactor is able to cool itself when the reactor height is sufficiently large. Additionally, the predicted flow is sensitive to how it is modeled since different approaches to modeling turbulence and fluid properties affect system performance.
Finally, adding a gas layer above the lead has a negligible effect on the overall performance of the system. This means that simpler models are sufficient to understand how the system behaves. It also shows that OpenFOAM is a viable option for modeling systems involving multiple fluids with large density differences. In turn, these findings provide insights that can support the design of safer and more reliable nuclear reactors in the future. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/student-papers/record/9231987
- author
- Wesström, Emma LU and Møller, August LU
- supervisor
- organization
- course
- MVKM01 20261
- year
- 2026
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- cfd, computational fluid dynamics, OpenFOAM, multiphase flow, volume of fluid, vof, liquid metal, thermal hydraulics, liquid lead, lead-cooled reactor, nuclear engineering, reactor, smr, small modular reactor, lead coolant, buoyancy, boussinesq, STAR-CCM+
- report number
- ISRN LUTMDN/TMHP-26/5682-SE
- ISSN
- 0282-1990
- language
- English
- id
- 9231987
- date added to LUP
- 2026-06-08 13:14:05
- date last changed
- 2026-06-08 13:14:05
@misc{9231987,
abstract = {{This study investigates the thermal-hydraulics of a simplified model of Blykalla's Swedish Advanced Lead-cooled Reactor (SEALER) using computational fluid dynamics (CFD) in OpenFOAM. The objective is to develop and verify a system-level model for forced and natural convection. The reactor cooling circuit is represented using porous media and volumetric source terms. Simulations are conducted using Reynolds-averaged Navier-Stokes (RANS), employing both eddy-viscosity and Reynolds stress turbulence models. The model is initially validated for single-phase steady-state forced convection by comparison with reference data. Strong agreement is obtained with respect to mass flow rate, core temperature difference, and pressure drop, indicating a consistent implementation of the system components. A noticeable deviation of \SI{18.6}{\%} is observed in the steam generator pressure drop, which suggests sensitivity to the porous media implementation. The turbulence model has a negligible impact on system-level performance during forced convection. For natural convection, the results show a strong dependence on reactor geometry, where increased system height enhances circulation and thermal distribution. The choice of turbulence model has a more pronounced effect under natural convection conditions, where the Reynolds stress model predicts a lower mass flow rate and exhibits reduced numerical stability compared to the eddy-viscosity models. The influence of thermophysical modeling is assessed by comparing a temperature-dependent property model with the Boussinesq approximation. The Boussinesq model predicts a higher mass flow rate and a lower temperature rise across the core, consistent with its simplified treatment of density variations. Multiphase simulations using a volume of fluid (VOF) approach are conducted to assess the capability to predict buoyancy-driven flow in the presence of large density differences. The results indicate that the presence of a gas phase has a negligible impact on system performance and that the OpenFOAM treatment of buoyancy is sufficient for system-level analysis.}},
author = {{Wesström, Emma and Møller, August}},
issn = {{0282-1990}},
language = {{eng}},
note = {{Student Paper}},
title = {{Modeling of Thermohydraulics in a Lead-Cooled Reactor System - A CFD Study Using OpenFOAM}},
year = {{2026}},
}