Draining of Primary Cooling Circuits in Actively Cooled Reactor Components: Modeling the Electrostatic Residual Ion Dump of the ITER Neutral Beam Test Facility

Draining is an important process for in-vessel actively cooled reactor components exposed to the effects of nuclear reactions. Activated corrosion products formed by the water interaction with metals in cooling circuits shall be controlled through coolant evacuation and component confinement in order to avoid spreading of contamination. The process shall be applied to the primary cooling circuits and to the ITER in-vessel actively cooled components, including the components of the neutral beam injectors (NBIs), whose prototype MITICA 1, 2 is under construction at the ITER Neutral Beam Test Facility in Padua. This work is focused on the electrostatic residual ion dump (ERID) of MITICA, for which the injection of pressurized nitrogen as inert gas is foreseen for blowing out of water from cooling circuits. The process is simulated by means of transient two-phase analyses. Parametric simulations as function of the inlet pressure are carried out to characterize the blowing-out process in terms of evacuation time and draining efficiency.