Three-dimensional numerical study on pool stratification behavior in molten corium-concrete interaction (MCCI) with MPS method

Xin Li, Ikken Sato, Akifumi Yamaji, Guangtao Duan

研究成果: Conference contribution

抜粋

Molten corium-concrete interaction (MCCI) is an important ex-vessel phenomenon that could happen during the late phase of a hypothetical severe accident in a light water reactor. When the molten corium, which is generally comprised of UO2, ZrO2 and metals such as zircalloy and stainless steel, is discharged into a dry reactor cavity, a stratified molten pool configuration with two immiscible oxidic and metallic phases can be expected to form and lead to MCCI. Compared to a homogenous oxidic molten pool configuration, the metallic phase in the stratified molten pool might influence the crust formation on the corium-concrete interface and consequently cause different concrete ablation behavior to evaluate MCCI progression concerning containment failure. In terms of this issue, past experimental studies, such as COMET-L, VULCANO VBS and MOCKA test series, have been carried out to investigate the influence of such oxidic and metallic stratified pool configuration on MCCI. The experimental results have shown that the metallic phase can have a significant impact on the axial and radial ablation kinetics that could influence the ablation patterns of reactor pit. As regards numerical studies, past numerical modeling of MCCI was generally based on Eulerian methods and simplified empirical approach to simulate solid/liquid phase change and evolving of corium/crust/concrete interface. Such modeling might be efficient but have shown deficiencies and inadequacies due to its Eulerian and empirical nature, which has suggested a necessity to seek for a more mechanistic approach for modeling of MCCI. In this sense, Moving Particle Semi-implicit (MPS) method is considered suitable for MCCI analysis for its advantages of tracking interfaces and modeling phase change accurately as a Lagrangian particle method. In the present study, a three-dimensional (3-D) numerical study has been performed to simulate COMET-L3 test carried out by KIT with a stratified molten pool configuration of simulant materials with improved MPS method. Solid/liquid phase change was simulated with types of solid and liquid particles with thermal and physical properties including temperature and solid fraction, which enabled tracking of the solid/liquid status of each particle to achieve accurate free surface and corium/crust/concrete interface capturing. The heat transfer between corium/crust/concrete was modeled with heat conduction between particles. Moreover, the potential influence of the siliceous aggregates was also investigated by setting up two different case studies since there was previous study indicating that siliceous aggregates in siliceous concrete might contribute to different axial and radial concrete ablation rates. The simulation results have indicated that metal melt as corium in MCCI can have completely different characteristics regarding concrete ablation pattern from that of oxidic corium, which needs to be taken into consideration when assessing the containment melt-through time in severe accident management.

元の言語English
ホスト出版物のタイトルThermal-Hydraulics and Safety Analyses
出版者American Society of Mechanical Engineers (ASME)
6B
ISBN(印刷物)9784888982566
DOI
出版物ステータスPublished - 2018 1 1
イベント2018 26th International Conference on Nuclear Engineering, ICONE 2018 - London, United Kingdom
継続期間: 2018 7 222018 7 26

Other

Other2018 26th International Conference on Nuclear Engineering, ICONE 2018
United Kingdom
London
期間18/7/2218/7/26

ASJC Scopus subject areas

  • Nuclear Energy and Engineering

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  • これを引用

    Li, X., Sato, I., Yamaji, A., & Duan, G. (2018). Three-dimensional numerical study on pool stratification behavior in molten corium-concrete interaction (MCCI) with MPS method. : Thermal-Hydraulics and Safety Analyses (巻 6B). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/ICONE26-82037