Fluid dynamics analysis of loss of vacuum accident of ITER cryostat

Highlights: • Analysis of the Cryostat LOVA (CrLOVA) by Ansys^©CFX. • Investigation of the consequences of different breach sizes of the Cryostat boundary. • Magnet Quench (MQ) and No Magnet Quench (NMQ) cases are discussed. • Evaluation of mass flow, temperature and pressure evolution in the Cryostat environment. • The pressure values in LOVA conditions are below the design limit pressure. - Abstract: The cryostat is one of the most important components of the ITER reactor because it provides a vacuum environment limiting the convective heat exchange between the components, especially the magnets. That's why it is designed to withstand negative pressure loads. In this paper a postulated breach of the cryostat boundary leading accident conditions involving the ingress of air into the ITER cryostat has been analyzed with ANSYS^©CFX. In the performed fluid-dynamic simulations suitable geometry, materials properties and initial and boundary conditions, thoroughly discussed, have been used. The main results indicated that the cryostat, even in the worst condition, seemed to withstand well LOVA without any relevant mechanical failure. The maximum pressure value resulted below the design limit pressure for the cryostat of 0.2 MPa for this accident. Finally it is worthy to remark that these results will be used for a further in depth evaluation of the structural performances of the cryostat itself.