Numerical study on the influence of steam condensation on hydrogen distribution in local compartments

Wang, D.; Tong, Lili; Cao, Xinde

doi:10.1016/j.anucene.2018.07.044

Cited by 8 publications

(3 citation statements)

References 13 publications

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“…Fine near-wall mesh resolution (dimensional length y + <1) is required for the former method, which requires a lot of computing resources; HMTA method with wall function can reduce requirements for mesh resolution to a certain degree (Ambrosini et al, 2014;Lee et al, 2015). The GASFLOW code uses HMTA method with wall function to model steam condensation in containment (Wang et al, 2018). There are some deficiencies in using this method when the flow field close to the wall is nearly stagnant, the condensation rate then somewhat depends on the cell size next to the condenser (Royl et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Improvement of Condensation Model With the Presence of Non-Condensable Gas for Thermal-Hydraulic Analysis in Containment

Wang

Tong

et al. 2021

Front. Energy Res.

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Steam condensation plays a key role in prediction of the pressure behavior and hydrogen distribution in the containment during a hypothetical loss-of-coolant accident or a severe accident in a light water nuclear reactor. The objective of this study is to evaluate and improve the condensation model in GASFLOW code. Reynolds analogy coupled with wall function and Chilton-Colburn empirical analogy is used to model heat and mass transfer in GASFLOW, which has requirements for dimensional distance of the first cell near the wall and some deficiencies in description of heat and mass transfer process in the stagnant zone. Based on the evaluation of original condensation, the results shows good agreement with COPAIN experiment cases where the mass fraction of air ranges from 76.7 to 86.4%. However, with the changes in geometry of the facility and the presence of helium, the original model has a large deviation in the prediction of pressure, temperature and gas distribution compared with MISTRA ISP47 (OECD International Standard Problem No. 47) experiment data. This work proposes a modified condensation model which uses McAdams correlation and Schlichting correlation with a weight factor to calculate natural, forced, or mixed convection heat transfer coefficient, and adopts Chilton-Colburn empirical analogy to model mass transfer. The modified model has no requirement for the dimensionless distance near the wall in heat and mass transfer calculation and improves the prediction performance of heat transfer in stagnant zone. The prediction result of the modified model shows good agreements with MISTRA ISP47 problem, and the error of it compared with COPAIN experiment data is within 25% which is the same as that predicted by the original model.

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Section: Introductionmentioning

confidence: 99%

Improvement of Condensation Model With the Presence of Non-Condensable Gas for Thermal-Hydraulic Analysis in Containment

Wang

Tong

et al. 2021

Front. Energy Res.

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“…Courses of the accidents have not been figured out yet, which significantly limit the application of hydrogen vehicles. Moreover, in severe accident initialized by loss of coolant accident (LOCA) for nuclear power plants, hydrogen is released to containment atmosphere or local compartment building as a result of zirconium‐water reaction happened in the core area, leading to the probable hydrogen explosion . Therefore, it's necessary to study the hydrogen distribution behavior in order to take effective hydrogen mitigation measures.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, in severe accident initialized by loss of coolant accident (LOCA) for nuclear power plants, hydrogen is released to containment atmosphere or local compartment building as a result of zirconium-water reaction happened in the core area, leading to the probable hydrogen explosion. 10 Therefore, it's necessary to study the hydrogen distribution behavior in order to take effective hydrogen mitigation measures. Research academies have conducted series of programs aiming at having further understanding of hydrogen dispersion, 11 mitigation effect, 12 and obstacle effect 13 after Fukushima nuclear accidents.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

2020

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Summary During hypothetical severe accidents in nuclear power plants, a large amount of hydrogen is generated rapidly as a result of zirconium‐water reaction and released into local compartments. Deflagration or detonation risk is probably caused by the uneven hydrogen distribution. Generally, buoyancy drives light combustible gas up to establish gas stratification. On the other hand, stratification may be destroyed by convection flow from steam injection due to coolant's discharge from the primary loop. The mechanism of erosion of stratification can be divided into buoyancy dominated and momentum dominated regimes, the priority of which depends on a nondimensional parameter, named of interaction Froude number. However, jet velocity and the diameter on the interface between steam and stratification are difficult to measure in experiments. Therefore, CFD method is adopted to capture a detailed velocity profile to solve this problem. In this article, a CFD model of single local compartment facility is built and helium distribution behavior within the local compartment is fully investigated, as a substitute of hydrogen, which is usually used in experiments. Prior to determining the interaction Froude number, four flow models, including laminar flow model, algebraic model, k‐ε turbulence model and shear stress transport (SST) k‐ω model are evaluated under three typical experimental stages, including light gas injection, the formation of stratification, and the erosion of stratification. Results show that SST k‐ω model can predict much better under these specific conditions in the small‐scaled configuration, compared to the experimental results. Next, with the setup of a helium stratification structure with homogeneous layer and gradient layer, the interaction between steam and gradient layer is analyzed in detail. The mechanisms of erosion of stratification can be divided into complete penetration, destruction from the bottom level to the top and soft dissolution without penetration, corresponding to the interaction Froude numbers of being greater than 1, close to 1, and far less than 1. The simulation results are consistent with relevant literature findings. The present work can help studying the complex hydrogen distribution process in local compartment and provide data for evaluation of postinerting strategy in severe accident management.

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Entropy and exergy analysis of the steam jet condensation in crossflow of subcooled water

Liu

Zhu

et al. 2023

Annals of Nuclear Energy

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Numerical study on the influence of steam condensation on hydrogen distribution in local compartments

Cited by 8 publications

References 13 publications

Improvement of Condensation Model With the Presence of Non-Condensable Gas for Thermal-Hydraulic Analysis in Containment

Improvement of Condensation Model With the Presence of Non-Condensable Gas for Thermal-Hydraulic Analysis in Containment

Numerical investigation on erosion of hydrogen stratification by steam jet within a local compartment

Entropy and exergy analysis of the steam jet condensation in crossflow of subcooled water

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