Numerical analysis of loss of vacuum accident (LOVA) and preliminary discussion about dust resuspension for CFETR

Loss of vacuum accident (LOVA) is the air ingress into the vacuum vessel (VV) due to the failure of components. The high speed air jet flow induced by the pressure difference between the ambient condition and the in-vessel condition may cause the dust migration, re-suspension bring risk to the integrity of components and radioactive release. The present work deals with the computational fluid dynamics (CFD) modeling of airflow characteristics in different scenarios during the LOVA for CFETR. Then, forces applied on the deposited particles are investigated, based on which the preliminary discussion are carried out to analyze the possibility of dust resuspension in various LOVA scenarios. The results show that the break location, break size and the operational status during the LOVA have significant influence on the key parameters related to airflow forces such as the friction velocity. Furthermore, the airflow force gradually plays the dominate role as the particle diameter increases. It preliminarily demonstrates the possibility of dust resuspension as the particle diameter changing. The results can provide references to study the dust re-suspension and implement accident mitigation measures.