Simulations and Experiments to Reach Numerical Multiphase Informations for Security Analysis on Large Volume Vacuum Systems Like Tokamaks

Abstract

Dust re-suspension as a consequences of loss of vacuum accident (LOVA) or loss of coolant accident (LOCA) situations inside a nuclear fusion plant (ITER-like) is an important issue for the workers’ safety and for the security of the plant. The dust size expected inside tokamaks like ITER is of the order of microns (0.1–1000 μm). Analysis of the thermo fluid-dynamics and transport phenomena involved during an accidental pressurization transitory is necessary in order to set up and operated tokamaks with careful consideration of the potential risks. Computational fluid dynamics (CFD) study of LOVA scenario is a challenging task for today numerical methods and models because it involves 3D large vacuum volumes, multiphase flows ranging from highly supersonic to nearly incompressible and heat transfer simultaneously. Present work deals with development and experimental validation of CFD model, which simulates the complex thermo fluid-dynamic field and gives some indication about internal hazardous dust mobilization phenomena during vessel filling at near vacuum conditions, for supporting first instant of LOVA safety analysis. The research activity had been carried out in the framework of EURATOM–ENEA Association—University of Rome Tor Vergata Quantum Electronics Plasma Physics and Materials Research Group.