scholarly journals Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident in the APR1400 Containment Using a Multi-Dimensional Hydrogen Analysis System

2020 ◽  
Author(s):  
Hyung Seok Kang ◽  
Jongtae Kim ◽  
Seong Wan Hong ◽  
Sang Baik Kim
Keyword(s):  
Nuclear Power ◽  
Turbulent Flame ◽  
Hydrogen Release ◽  
Severe Accident ◽  
Flame Acceleration ◽  
Turbulent Flame Speed ◽  
Analysis Methodology ◽  
Hydrogen Flame ◽  
Hydrogen Analysis ◽  
Analysis System

Korea Atomic Energy Research Institute (KAERI) established a multi-dimensional hydrogen analysis system to evaluate a hydrogen release, distribution, and combustion in the containment of a nuclear power plant using MAAP, GASFLOW, and COM3D. KAERI developed the COM3D analysis methodology on the basis of the COM3D validation results against the experiments of ENACCEF and THAI. The proposed analysis methodology accurately predicts the peak overpressure with an error range of approximately ±10% using the Kawanabe turbulent flame speed model. KAERI performed a hydrogen flame acceleration analysis using the multi-dimensional hydrogen analysis system for a severe accident initiated by a station blackout (SBO) under the assumption of 100% metal-water reaction in the reactor pressure vessel for evaluating an overpressure buildup in the Advanced Power Reactor 1400 MWe (APR1400). The COM3D calculation results using the established analysis methodology showed that the calculated peak pressure in the containment was much lower than the fracture pressure of the APR1400 containment. This calculation result may have resulted from a large air volume of the containment, a reduced hydrogen concentration owing to passive auto-catalytic recombiners installed in the containment, and a lot of stem presence during the hydrogen flame acceleration in the containment. Therefore, we can know that the current design of the APR1400 containment maintains its integrity when the flame acceleration occurs during the severe accident initiated by the SBO accident.

scholarly journals Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident in the APR1400 Containment Using a Multi-Dimensional Hydrogen Analysis System

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6151
Author(s):  
Hyung Seok Kang ◽  
Jongtae Kim ◽  
Seong Wan Hong ◽  
Sang Baik Kim
Keyword(s):  
Turbulent Flame ◽  
Hydrogen Combustion ◽  
Hydrogen Release ◽  
Severe Accident ◽  
Flame Acceleration ◽  
Turbulent Flame Speed ◽  
Analysis Methodology ◽  
Hydrogen Flame ◽  
Hydrogen Analysis ◽  
Analysis System

Korea Atomic Energy Research Institute (KAERI) established a multi-dimensional hydrogen analysis system to evaluate hydrogen release, distribution, and combustion in the containment of a Nuclear Power Plant (NPP), using MAAP, GASFLOW, and COM3D. In particular, KAERI developed an analysis methodology for a hydrogen flame acceleration, on the basis of the COM3D validation results against measured data of the hydrogen combustion tests in the ENACCEF and THAI facilities. The proposed analysis methodology accurately predicted the peak overpressure with an error range of approximately ±10%, using the Kawanabe model used for a turbulent flame speed in the COM3D. KAERI performed a hydrogen flame acceleration analysis using the multi-dimensional hydrogen analysis system for a severe accident initiated by a station blackout (SBO), under the assumption of 100% metal–water reaction in the Reactor Pressure Vessel (RPV), to evaluate an overpressure buildup in the containment of the Advanced Power Reactor 1400 MWe (APR1400). The magnitude of the overpressure buildup in the APR1400 containment might be used as a criterion to judge whether the containment integrity is maintained or not, when the hydrogen combustion occurs during a severe accident. The COM3D calculation results using the established analysis methodology showed that the calculated peak pressure in the containment was lower than the fracture pressure of the APR1400 containment. This calculation result might have resulted from a large air volume of the containment, a reduced hydrogen concentration owing to passive auto-catalytic recombiners installed in the containment during the hydrogen release from the RPV, and a lot of stem presence during the hydrogen combustion period in the containment. Therefore, we found that the current design of the APR1400 containment maintained its integrity when the flame acceleration occurred during the severe accident initiated by the SBO accident.

Simulation of ENACCEF2 Premixed Hydrogen-Air Mixture Deflagration Experiment Using OpenFOAM

2020 ◽  
Author(s):  
Justina Jaseliūnaitė ◽  
Mantas Povilaitis
Keyword(s):  
Nuclear Power ◽  
Turbulent Flame ◽  
Front Propagation ◽  
Combustible Mixture ◽  
Hydrogen Combustion ◽  
Severe Accident ◽  
Variable Model ◽  
Flame Acceleration ◽  
Combustion Simulation ◽  
Acceleration Tube

Abstract During a severe accident in a nuclear power plant, hydrogen would be generated due to the oxidation of metallic components in steam atmosphere. In the containment hydrogen would form a combustible mixture, posing a deflagration or even detonation risk threatening the integrity of the containment. In order to estimate possible loads generated by the hydrogen combustion, reliable numerical tools are needed to simulate the deflagration process. Recently, the French MITHYGENE project consortium and the European Technical Safety Organization Network (ETSON) organized a benchmark on hydrogen combustion to identify the current level of the computational tools in the area of hydrogen combustion simulation under a severe accident typical conditions. The benchmark was based on the experiments performed in the ENACCEF2 facility. This paper presents post-benchmark simulations of the selected ENACCEF2 facility premixed hydrogen combustion experiment. The presented simulations were performed using a custom-built turbulent combustion OpenFOAM solver based on the progress variable model. Turbulent flame acceleration phase in the acceleration tube was well predicted. Furthermore, the simulations were able to capture the interaction between the flame and shock wave which was generated by the turbulent deflagration flame and reflected at the end of the ENACCEF2 tube. The overall numerical results show good agreement with the qualitative and quantitative behavior of the velocity results and flame front propagation.

scholarly journals Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident Initiated by SBLOCA in the APR1400 Containment

Hydrogen ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 28-42
Author(s):  
Hyung-Seok Kang ◽  
Jongtae Kim ◽  
Seong-Wan Hong
Keyword(s):  
Nuclear Power ◽  
Peak Pressure ◽  
Power Reactor ◽  
Hydrogen Combustion ◽  
Hydrogen Release ◽  
Severe Accident ◽  
Hydrogen Distribution ◽  
Nuclear Power Reactor ◽  
Flame Acceleration ◽  
Fracture Pressure

We performed a hydrogen combustion analysis in the Advanced Power Reactor 1400 MWe (APR1400) containment during a severe accident initiated by a small break loss of coolant accident (SBLOCA) which occurred at a lower part of the cold leg using a multi-dimensional hydrogen analysis system (MHAS) to confirm the integrity of the APR1400 containment. The MHAS was developed by combining MAAP, GASFLOW, and COM3D to simulate hydrogen release, distribution and combustion in the containment of a nuclear power plant during the severe accidents in the containment of a nuclear power reactor. The calculated peak pressure due to the flame acceleration by the COM3D, using the GASFLOW results as an initial condition of the hydrogen distribution, was approximately 555 kPa, which is lower than the fracture pressure 1223 kPa of the APR1400 containment. To induce a higher peak pressure resulted from a strong flame acceleration in the containment, we intentionally assumed several things in developing an accident scenario of the SBLOCA. Therefore, we may judge that the integrity of the APR1400 containment can be maintained even though the hydrogen combustion occurs during the severe accident initiated by the SBLOCA.

Hydrogen–Air–Steam Deflagration Experiment Simulated Using Different Turbulent Flame-Speed Closure Models

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Holler Tadej ◽  
Ed M. J. Komen ◽  
Kljenak Ivo
Keyword(s):  
Flame Propagation ◽  
Nuclear Power ◽  
Large Scale ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Energy Output ◽  
Combustion Model ◽  
Turbulent Flame Speed ◽  
Modeling Approach ◽  
Combustion Models

The paper presents the computational fluid dynamics (CFD) combustion modeling approach based on two combustion models. This modeling approach was applied to a hydrogen deflagration experiment conducted in a large-scale confined experimental vessel. The used combustion models were Zimont's turbulent flame-speed closure (TFC) model and Lipatnikov's flame-speed closure (FSC) model. The conducted simulations are aimed to aid identifying and evaluating the potential hydrogen risks in nuclear power plant (NPP) containment. The simulation results show good agreement with experiment for axial flame propagation using the Lipatnikov combustion model. However, substantial overprediction in radial flame propagation is observed using both combustion models, which consequently results also in overprediction of the pressure increase rate and overall combustion energy output. As assumed for a large-scale experiment without any turbulence inducing structures, the combustion took place in low-turbulence regimes, where the Lipatnikov combustion model, due to its inclusion of quasi-laminar source term, has advantage over the Zimont model.

Large-Scale Homogeneous Hydrogen-Air-Steam Deflagration Experiment Simulated Using Two Turbulent Flame Speed Closure Models

2016 ◽  
Author(s):  
Tadej Holler ◽  
Varun Jain ◽  
Ed M. J. Komen ◽  
Ivo Kljenak
Keyword(s):  
Flame Propagation ◽  
Nuclear Power ◽  
Large Scale ◽  
Turbulent Flame ◽  
Turbulent Flames ◽  
Flame Speed ◽  
Energy Output ◽  
Combustion Model ◽  
Turbulent Flame Speed ◽  
Combustion Models

The CFD combustion modeling approach based on two combustion models was applied to a hydrogen deflagration experiment conducted in a large-scale confined experimental vessel. The used combustion models were Zimont’s Turbulent Flames Speed Closure (TFC) model and Lipatnikov’s Flame Speed Closure (FSC) model. The conducted simulations are aimed to aid identifying and evaluating the potential hydrogen risks in Nuclear Power Plant (NPP) containment. The simulation results show good agreement with experiment for axial flame propagation using the Lipatnikov combustion model. However substantial overprediction in radial flame propagation is observed using both combustion models, which consequently results also in overprediction of the pressure increase rate and overall combustion energy output. As assumed for a large-scale experiment without any turbulence inducing structures, the combustion took place in low-turbulence regimes, where the Lipatnikov combustion model, due to its inclusion of quasi-laminar source term, has advantage over the Zimont model.

scholarly journals Моделирование окисления расплава активной зоны ядерного реактора при наличии оксидной корки на поверхности расплава

2021 ◽  
Vol 91 (2) ◽  
pp. 232
Author(s):  
В.Б. Хабенский ◽  
В.И. Альмяшев ◽  
В.С. Грановский ◽  
Е.В. Крушинов ◽  
С.А. Витоль ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Solid Phase ◽  
Reactor Vessel ◽  
Hydrogen Release ◽  
Severe Accident ◽  
Water Steam ◽  
Exothermic Reactions ◽  
Realistic Situation ◽  
Water Reactors

At a severe accident of nuclear power plants with light-water reactors, the most effective way to localize the forming melt (corium) is to keep it in the cooled reactor vessel, the integrity of which depends on the value of heat flux from the melt to the reactor vessel. In this case, one of the critical processes is the melt oxidation by a water steam or a steam-air mixture. It process can lead to a significant increase in the thermal load on the reactor vessel due to a heat of exothermic reactions of oxidation of reducing agents, which presents in the melt, a thickness decreasing of the metallic part of the molten pool, and a hydrogen release. All of these factors strictly depends on the rate of oxidation. When considering the conditions of melt oxidation, it taken into account that for the accepted scenarios of a severe accident, the most realistic situation is the presence of a solid-phase oxide layer (oxidic crust) on the melt surface. Under these conditions, a dependence for calculating the rate of core melt oxidation based on the diffusion model proposed and its validation by using the obtained experimental data performed.

Fluid Dynamic Analysis on Hydrogen Deflagration in Vertical Flow Channel With Annular Obstacles

2017 ◽  
Author(s):  
Toshinori Matsumoto ◽  
Masatoshi Sato ◽  
Tomoyuki Sugiyama ◽  
Yu Maruyama
Keyword(s):  
Flame Propagation ◽  
Nuclear Power ◽  
Fluid Dynamic ◽  
Vertical Channel ◽  
Equation Model ◽  
Hydrogen Combustion ◽  
Severe Accident ◽  
Computational Techniques ◽  
Wall Functions ◽  
Flame Acceleration

Hydrogen combustion including deflagration and detonation could become a significant threat to the integrity of containment vessel or reactor building in a severe accident of nuclear power stations. In the present study, numerical analyses were carried out for the ENACCEF No.153 test to develop computational techniques to evaluate the flame acceleration phenomenon during the hydrogen deflagration. This experiment investigated flame propagation in the hydrogen-air premixed gas in a vertical channel with flow obstacles. The reactingFoam solver of the open source CFD code, OpenFOAM, was used for the present analysis. Nineteen elementary chemical reactions were considered for the overall process of the hydrogen combustion. For a turbulent flow, renormalization group (RNG) k-ε two-equation model was used in combination with wall functions. Three manners of nodalization were applied and its influences on the flame propagation acceleration were discussed.

Effect on Hydrogen Risk of Initial Gas Injection Time During AP1000 Post-Inerting

2016 ◽  
Author(s):  
XueFeng Lyu ◽  
YanLin Chen ◽  
XiaoBo Li ◽  
ShengFei Wang ◽  
Yu Yu ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Hydrogen Diffusion ◽  
Gas Injection ◽  
Inert Gas ◽  
Severe Accident ◽  
Injection Time ◽  
Steam Generation ◽  
Flame Acceleration ◽  
Average Temperature ◽  
Total Elimination

To calculate the hydrogen risk at severe accident of small break of cold leg in 1# steam generation compartment with ADS4 invalid in AP1000 nuclear power plant, and apply the results to level2 probabilistic safety analysis, we study the effect of initial gas injection time on reducing hydrogen risk during AP1000 post-inerting, the initial gas injection times are 300 second, 500second, 700second, respectively. First, analyzing the total elimination of hydrogen by recombiners. Then, analyzing the average hydrogen mole fraction, flame acceleration factor in 1# steam generation compartment and in upper space of containment. Finally, analyzing the pressure and average temperature in containment. The results show that, the premature injection of inert gas can slow down hydrogen diffusion rate from 1# steam generation compartment to the upper space of containment, which causes hydrogen risk rising in 1# steam generation compartment. Post-inerting can ease hydrogen risk in upper space of containment, but can’t ease hydrogen risk in 1# steam generation compartment effectively. The pressure of containment is only relevant to the total mass of inert gas, and the pressure of containment is always less than limit pressure, so the containment breakage is nearly impossible.

Development and Validation of the Parallel All-Speed CFD Code GASFLOW-MPI for Detonation of Premixed H2-Air Mixture in a Hemispherical Balloon

2017 ◽  
Author(s):  
Jianjun Xiao ◽  
Wolfgang Breitung ◽  
Mike Kuznetsov ◽  
Jack Travis ◽  
Reinhard Redlinger
Keyword(s):  
Nuclear Power ◽  
Nuclear Reactor ◽  
Turbulent Dispersion ◽  
Severe Accident ◽  
Flame Acceleration ◽  
Model Predictions ◽  
Computational Fluid Dynamics Cfd ◽  
Detonation Transition ◽  
Reliability And Robustness ◽  
Development And Validation

The objective was to develop a validated computational fluid dynamics (CFD) based approach for predicting hydrogen detonations and the mechanical loads. Applications of interest were scenarios relevant to hydrogen explosion risk assessment in nuclear power plant under hypothetical severe accident. Model developments were conducted within the framework of the parallel scientific computational tool GASFLOW-MPI thanks to its effectiveness, reliability and robustness in predicting all-speed flows. Validation was completed for hydrogen detonation phenomena in 3-D hemispherical hydrogen cloud. Excellent comparisons between experimental data and model predictions were observed. With the developed detonation modeling capability, the all-speed CFD code GASFLOW-MPI can be applied to model both turbulent dispersion and hydrogen detonation phenomena that occurred in the nuclear reactor containment during severe accident. Further model developments and validations will be performed for flame acceleration (FA) and deflagration to detonation transition (DDT).

CFD Simulation of Deflagration to Detonation Transition for Nuclear Safety

2014 ◽  
Author(s):  
Eduardo Hwang ◽  
Felipe Porto Ribeiro ◽  
Jian Su
Keyword(s):  
Shock Wave ◽  
Power Plants ◽  
Stokes Equations ◽  
Burning Velocity ◽  
Turbulent Flame ◽  
Flame Acceleration ◽  
Turbulent Flame Speed ◽  
Combustion Models ◽  
Deflagration To Detonation Transition ◽  
Detonation Transition

The present work aims to develop an efficient methodology for evaluating the Deflagration to Detonation Transition (DDT) in accidental scenarios from inherent hydrogen risk in water-cooled NPPs (Nuclear Power Plants). The physical problem is flame acceleration through a confined geometry congested with periodic obstacles, up to formation of a travelling shock wave. The problem was modeled by the Reynolds-averaged Navier-Stokes equations (RANS) with the standard k-ε turbulence model. There are two main combustion models: EDC (Eddy Dissipation Concept) whose equations are the transport equations for chemical species involved; and BVM (Burning Velocity Model) a transport equation for reaction progress (one scalar), to be used with three available turbulent flame speed correlations (Peters, Mueller and Zimont), and a new formulation based on Piston Action of the expanding burnt gas. The present work compared characteristics of these combustion models regarding flame acceleration in the midsize mc043 experiment, in order to apply the proposed combustion model in large scale DDT simulations. Experiment mc043 is consists of igniting a 12-meter long tube with 70 annular obstacles, filled with lean hydrogen-air mixture. The numerical results revealed that the proposed model is superior to BVM model correlations in predicting shock wave formation, and may provide a computationally more efficient option to the EDC model.

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