Comparative study on the effect of reactor internal structure geometry modeling methods on the prediction accuracy for PWR internal flow distribution

Lee, Gong Hee; Bang, Young Seok; Woo, Seonock; Cheong, Ae Ju

doi:10.1016/j.anucene.2014.03.020

Cited by 21 publications

(5 citation statements)

References 9 publications

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“…Recent years have seen Computational Fluid Dynamics (CFD) methods increasingly applied to single phase flow simulation in complex geometries relevant to nuclear engineering. To name just a few, Höhne et al (Höhne, et al 2008) simulated the mixing of de-borated slugs of water through the ROCOM facility, Lee et al (Lee, et al 2014) studied the effect of PWR internals on core inlet flow, and Jeong et al (Jeong and Han 2008) simulated the flow field in downcomer and lower plenum of a PWR, explicitly accounting for reactor internals. The enduring trend of increasing availability of computational resources continues to add larger, higher resolution models to the class of tractable problems.…”

Section: Motivationmentioning

confidence: 99%

A novel multi-scale domain overlapping CFD/STH coupling methodology for multi-dimensional flows relevant to nuclear applications

Grunloh

Manera

2017

Nuclear Engineering and Design

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A novel multi-scale domain overlapping coupling methodology designed to couple a computational fluid dynamics (CFD) code with a system thermal hydraulic (STH) code was developed and its performance was investigated. The methodology has been implemented in the coupling infrastructure code Janus, developed at the University of Michigan, providing methods for the on-the-fly data transfer through memory between the commercial CFD code STAR-CCM+ and the US NRC best-estimate thermal hydraulic system code TRACE. Coupling between these two software packages is motivated by the desire to extend the range of applicability of TRACE to scenarios in which local momentum and energy transfer are important, such as three-dimensional mixing of localized slugs of deborated or cold water in the downcomer and lower plenum of a reactor pressure vessel. The intra-fluid shear forces necessary to correctly capture these effects are neglected in the TRACE equations of motion, but are readily calculated from CFD solutions. CFD/STH coupling implementations therefore have applications in reactor transients such as boron dilution scenarios, Anticipated Transient Without Scram (ATWS) and Main Steam Line Break (MSLB). The proposed method is based on aliasing all spatial sources and sinks of momentum in the CFD domain as frictional losses in the system code domain. The internal velocity fields and, consequently, the inertial component of the pressure field are maintained consistent between the CFD and STH domains through a complementary velocity-matching interface. In this paper, coupled simulations are performed on Cartesian and cylindrical geometry with emphasis on consistency, convergence, and stability during transient scenarios. Results show that the presented domain overlapping coupling method is capable of adjusting pressure and velocity profiles of multi-dimensional system code solutions to match CFD solutions accurately. Important characteristics of transient simulations were found to include the background flow rate, specifically the stabilizing effect of viscous forces, as well as the time derivative of the flow rate. Under certain adverse conditions, the basic coupling method is found to produce unstable behavior. A stabilization method for adjusting CFD data is laid out and found to significantly improve the method's performance under the most challenging conditions. Recommendations are laid out for further improving the coupling via advanced time stepping methods.

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Section: Motivationmentioning

confidence: 99%

A novel multi-scale domain overlapping CFD/STH coupling methodology for multi-dimensional flows relevant to nuclear applications

Grunloh

Manera

2017

Nuclear Engineering and Design

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“…The mass flow rates in center fuel assemblies are higher than that in peripheral fuel assemblies at core inlets [13]. Many researchers have made detailed analysis on the coolant mixing in the reactor, flow field in the reactor pressure vessel, flow distribution at core inlets using CFD methods [14][15][16][17][18][19][20][21][22], however the behavior of single pellet in a reactor nuclear, PWR type, due to variation on inlet temperature and mass flow rate has not been investigated as a fundamental study.…”

Section: Introductionmentioning

confidence: 99%

Simulation on the Effect of Coolant Inlet Temperature and Mass-Flowrate Variations to the Temperature Distribution in Single Pellet Thermal Reactor Core

Yusibani

Helmiza

Fashbir

et al. 2021

J. Penelit. Fis. Apl.

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An important factor in the development of nuclear energy is reactor safety. The performance of heat transfer from nuclear fuel to coolant is the main key to the reactor safety. This paper presents simulation on temperature distribution in two-dimensional laminar flow for single pellet thermal reactor with variation on temperature inlet and mass-flowrate. The OpenFoam platform (SimFlow 3.1) has been used for the computational and numerical analysis. The simulation is carried out on a single pellet with an aspect ratio of 1.2. The variations in the mass velocity of the coolant flow are 10, 100, and 14300 kg×s-1 with a constant coolant temperature of 552 K, and the variations of the input coolant temperature are 300, 552, and 1000 K with a constant mass-flowrate of 10 kg×s-1. The results obtained from the simulation show that for variations in the input coolant temperature of 300, 552, and 1000 K, the fuel temperature can be reduced respectively by 34, 26, and 14 K. At the fastest variation in the coolant mass-flowrate of 14300 kg×s-1, the coolant temperature around the pellet rises by 396 K. The decrease in fuel temperature is significant if the mass-flowrate of the input coolant flow is relatively low.

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“…In recent years, however, Computational Fluid Dynamics (CFD) methods have been increasingly applied to the simulation of single phase flow in complex geometries relevant to nuclear engineering. To name just a few, Höhne et al [5] simulated the mixing of de-borated slugs of water through the ROCOM facility, Lee et al [6] studied the effect of PWR internals on core inlet flow, and Jeong et al [7] simulated the flow field in downcomer and lower plenum of a PWR, explicitly accounting for reactor internals. The enduring trend of increasing availability of computational resources continues to add larger, higher resolution models to the class of tractable problems.…”

mentioning

confidence: 99%

A novel domain overlapping strategy for the multiscale coupling of CFD with 1D system codes with applications to transient flows

Grunloh

Manera

2016

Annals of Nuclear Energy

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A novel multiscale coupling methodology based on a domain overlapping approach has been developed to couple a computational fluid dynamics code with a best-estimate thermal hydraulic code. The methodology has been implemented in the coupling infrastructure code Janus, developed at the University of Michigan, providing methods for the online data transfer between the commercial computational fluid dynamics code STAR-CCM+ and the US NRC best-estimate thermal hydraulic system code TRACE. Coupling between these two software packages is motivated by the desire to extend the range of applicability of TRACE to scenarios in which local momentum and energy transfer are important, such as three-dimensional mixing. These types of flows are relevant, for example, in the simulation of passive safety systems including large containment pools, or for flow mixing in the reactor pressure vessel downcomer of current light water reactors and integral small modular reactors. The intrafluid shear forces neglected by TRACE equations of motion are readily calculated from computational fluid dynamics solutions. Consequently, the coupling methods used in this study are built around correcting TRACE solutions with data from a corresponding STAR-CCM+ solution. Two coupling strategies are discussed in the paper: one based on a novel domain overlapping approach specifically designed for transient operation, and a second based on the well-known domain decomposition approach. In the present paper, we discuss the application of the two coupling methods to the simulation of open and closed loops in both steady state and transient operation. The objective of this study is to examine the performance of each coupling method in terms of convergence, consistency, and numerical stability. As expected, the results produced by the two methods were found to be identical, once numerical convergence is achieved, and consistent with the standalone STAR-CCM+ solution in both steady state and transient cases. However, the domain overlapping method was found to achieve convergence at larger integration time steps than the domain decomposition approach and exhibited superior convergence and numerical stability characteristics in both steady state and transient scenarios.

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Comparative study on the effect of reactor internal structure geometry modeling methods on the prediction accuracy for PWR internal flow distribution

Cited by 21 publications

References 9 publications

A novel multi-scale domain overlapping CFD/STH coupling methodology for multi-dimensional flows relevant to nuclear applications

A novel multi-scale domain overlapping CFD/STH coupling methodology for multi-dimensional flows relevant to nuclear applications

Simulation on the Effect of Coolant Inlet Temperature and Mass-Flowrate Variations to the Temperature Distribution in Single Pellet Thermal Reactor Core

A novel domain overlapping strategy for the multiscale coupling of CFD with 1D system codes with applications to transient flows

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