Large eddy simulation on turbulent heat transfer in reactor vessel lower head corium pools

Zhang, Luteng; Luo, Simin; Zhang, Yapei; Tian, Wenxi; Su, G.H.; Qiu, Suizheng

doi:10.1016/j.anucene.2017.08.055

Cited by 37 publications

(2 citation statements)

References 21 publications

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“…Prior studies report the complex and unique heat transfer characteristics of forced and natural convection in fluids with IHG. Simulated and observed phenomena include unstable thermal stratification, turbulence at low Rayleigh number, and oscillating temperature and velocity fields (Sehgal et al, 1996;Zhang et al, 2018;Pini et al, 2016). A numerical and experimental study of a natural circulation loop with IHG predicts nearly uniform radial temperature profiles and higher buoyant velocities than with wall heating alone (Jeong et al, 2018).…”

Section: Evaluation Of Convection Correlationsmentioning

confidence: 99%

Thermal-hydraulic design methodology and trade-off studies for a dual-salt breed-and-burn molten salt reactor

Kasam

Lee

Shwageraus

2020

Nuclear Engineering and Design

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A methodology is developed for thermal-hydraulic analysis and design of a breed-and-burn molten salt reactor (BBMSR). By using separate fuel and coolant molten salts, the BBMSR is proposed to overcome key materials limitations of traditional breed-and-burn and molten salt reactor designs.The BBMSR fuel concept includes an inner wall that divides the ascending and descending flows of naturally convecting fuel salt. A finite-difference model (FDM) is developed to iteratively solve for the temperature and velocity distributions in both sections of the concentric fuel. The FDM is used to perform parametric studies of the effect of fuel geometry and heat generation rate on the heat transfer performance of the fuel. The FDM is then integrated into a design search algorithm that identifies the operational limits for a given BBMSR fuel geometry, within a set of defined constraints. A range of thermal-hydraulic fuel design options are evaluated, and trade-off studies are performed to identify the most promising fuel design space for competitive power production and neutronic efficiency in the BBMSR.

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Section: Evaluation Of Convection Correlationsmentioning

confidence: 99%

Thermal-hydraulic design methodology and trade-off studies for a dual-salt breed-and-burn molten salt reactor

Kasam

Lee

Shwageraus

2020

Nuclear Engineering and Design

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“…However, Dinh and Nourgaliev pointed out that RANS models such as the k − ε model are not suitable for modeling the turbulent natural convection flow (Dinh and Nourgaliev, 1997) because the thermo-fluid behavior in the molten pool is characterized as internally heated (IH) natural convection, which is different from the force convection flow. Large-eddy simulation (LES) has also been implemented to simulate molten pool convection, but more qualification and quantification are needed (Zhang et al, 2018). On the other hand, direct numerical simulation (DNS) can provide the most accurate simulation results because it does not have assumption models on the turbulence flows (Grötzbach and Wörner, 1999;Yildiz et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Scalability of Nek5000 on High-Performance Computing Clusters Toward Direct Numerical Simulation of Molten Pool Convection

2022

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In a postulated severe accident, a molten pool with decay heat can form in the lower head of a reactor pressure vessel, threatening the vessel’s structural integrity. Natural convection in molten pools with extremely high Rayleigh (Ra) number is not yet fully understood as accurate simulation of the intense turbulence remains an outstanding challenge. Various models have been implemented in many studies, such as RANS (Reynolds-averaged Navier–Stokes), LES (large-eddy simulation), and DNS (direct numerical simulation). DNS can provide the most accurate results but at the expense of large computational resources. As the significant development of the HPC (high-performance computing) technology emerges, DNS becomes a more feasible method in molten pool simulations. Nek5000 is an open-source code for the simulation of incompressible flows, which is based on a high-order SEM (spectral element method) discretization strategy. Nek5000 has been performed on many supercomputing clusters, and the parallel performance of benchmarks can be useful for the estimation of computation budgets. In this work, we conducted scalability tests of Nek5000 on four different HPC clusters, namely, JUWELS (Atos Bullsquana X1000), Hawk (HPE Apollo 9000), ARCHER2 (HPE Cray EX), and Beskow (Cray XC40). The reference case is a DNS of molten pool convection in a hemispherical configuration with Ra = 1011, where the computational domain consisted of 391 million grid points. The objectives are (i) to determine if there is strong scalability of Nek5000 for the specific problem on the currently available systems and (ii) to explore the feasibility of obtaining DNS data for much higher Ra. We found super-linear speed-up up to 65536 MPI-rank on Hawk and ARCHER2 systems and around 8000 MPI-rank on JUWELS and Beskow systems. We achieved the best performance with the Hawk system with reasonably good results up to 131072 MPI-rank, which is attributed to the hypercube technique on its interconnection. Given the current HPC technology, it is feasible to obtain DNS data for Ra = 1012, but for cases higher than this, significant improvement in hardware and software HPC technology is necessary.

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Assessment of different turbulence models on the large scale internal heated water pool natural convection simulation

Wei

Chen

2019

Annals of Nuclear Energy

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Large eddy simulation on turbulent heat transfer in reactor vessel lower head corium pools

Cited by 37 publications

References 21 publications

Thermal-hydraulic design methodology and trade-off studies for a dual-salt breed-and-burn molten salt reactor

Thermal-hydraulic design methodology and trade-off studies for a dual-salt breed-and-burn molten salt reactor

Scalability of Nek5000 on High-Performance Computing Clusters Toward Direct Numerical Simulation of Molten Pool Convection

Assessment of different turbulence models on the large scale internal heated water pool natural convection simulation

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