The EVITA programme: Experimental and numerical simulation of a fluid ingress in the cryostat of a water-cooled fusion reactor

In the frame of the deterministic approach in the safety analysis of the ITER reactor, it is postulated that a helium cooling line from the cryogenic system and one coolant pipe of the firstwall/blanket primary heat transport system are damaged simultaneously in the cryostat. This event is selected to bound possible damage to the systems in the cryostat. The computer codes, which are used for the assessment of ITER safety, can be validated against the EVITA experiment, which has been designed for the simulation of the physical phenomena occurring during a coolant ingress into the cryostat, namely ice formation on a cryogenic structure, heat transfer coefficient between walls and fluid, flashing, two-phase critical flow. The comparison between calculations and experiments allows the ability of the computer codes to treat the relevant physical phenomena to be assessed.