Experimental validation of Direct Contact Condensation at ITER VVPSS prototypical thermal-hydraulic conditions

The objective of this PhD thesis is to study the Direct Contact Condensation (DCC) of steam in water at very small pressures near vacuum. These conditions are realized in safety systems of nuclear fusion reactors, in particular in the Vacuum Vessel Pressure Suppression System (VVPSS) of ITER. The Vacuum Vessel Pressure Suppression System (VVPSS) is a key system of the ITER plant. It is designed to protect the Vacuum Vessel (VV) and the related components from over pressure conditions in the case of an Ingress of Coolant Event (ICE). This event could occur during the normal operating conditions as well as during accidental conditions. The ITER Pressure Suppression System has thermal-hydraulic operating conditions which are not the standard conditions of fission nuclear power systems, whose pressure suppression systems are characterized by steam condensed at pressures near the atmospheric pressure and using sub-cooled water. For this reason, this research is original in the nuclear field. In other words, the direct contact condensation in the thermal-hydraulic conditions of ITER has not been ever studied in detail. The PhD research has investigated experimentally the steam direct contact condensation at the ITER prototypical conditions.