SPIDER is a 100 kV negative hydrogen/deuterium ion beam source, under operation at Consorzio RFX, which will be exploited for assessment and optimization of the radio frequency source that will be employed in the ITER Neutral Beam Injectors. The in-vessel actively cooled components shall be drained in case of major maintenance to limit as much as possible atmospheric corrosion inside the circuits and components, to prevent water spreading, and finally to allow the execution of vacuum leak tests of the circuits before re-installation of the Beam Source inside the Vacuum Vessel. Draining of hydraulic circuits is first foreseen by gravity after opening of the end connections of hydraulic circuits and then by blowing-out with inert gas. Injection of pressurized nitrogen is simulated by means of one-dimensional models to perform transient two-phase analyses of the blowing-out process with identification of flow regimes. Moreover, three-dimensional transient two-phase analyses are used to deeply investigate the behaviour of components made of complex geometries. Parametric simulations as function of the inlet pressure are carried out to characterize the blowing-out process in terms of flow rate, evacuation time and draining efficiency. The gas and water flow rates are evaluated recognising Rayleigh-Taylor instabilities which occur when the light nitrogen is pushing the heavy water. The maximum allowable pressure for blowing out, in accordance with the Pressure Equipment Directive (PED), is fixed to 1.1 MPa in order to stay in the Sound Engineering Practice category (low hazard level without CE marking). Among all the applied draining pressures, the range between 0.15-0.4 MPa is considered to perform the blowing out process in order to limit the gas speed and take into account possible pressure fluctuations. The analyses were fundamental to design a blowing-out system capable of satisfying the requirements of the different components belonging to the SPIDER Beam Source.
Draining analyses of the primary cooling circuits of the SPIDER Beam Source
Zaupa Matteo;Dalla Palma Mauro;Zaccaria Pierluigi
2020
Abstract
SPIDER is a 100 kV negative hydrogen/deuterium ion beam source, under operation at Consorzio RFX, which will be exploited for assessment and optimization of the radio frequency source that will be employed in the ITER Neutral Beam Injectors. The in-vessel actively cooled components shall be drained in case of major maintenance to limit as much as possible atmospheric corrosion inside the circuits and components, to prevent water spreading, and finally to allow the execution of vacuum leak tests of the circuits before re-installation of the Beam Source inside the Vacuum Vessel. Draining of hydraulic circuits is first foreseen by gravity after opening of the end connections of hydraulic circuits and then by blowing-out with inert gas. Injection of pressurized nitrogen is simulated by means of one-dimensional models to perform transient two-phase analyses of the blowing-out process with identification of flow regimes. Moreover, three-dimensional transient two-phase analyses are used to deeply investigate the behaviour of components made of complex geometries. Parametric simulations as function of the inlet pressure are carried out to characterize the blowing-out process in terms of flow rate, evacuation time and draining efficiency. The gas and water flow rates are evaluated recognising Rayleigh-Taylor instabilities which occur when the light nitrogen is pushing the heavy water. The maximum allowable pressure for blowing out, in accordance with the Pressure Equipment Directive (PED), is fixed to 1.1 MPa in order to stay in the Sound Engineering Practice category (low hazard level without CE marking). Among all the applied draining pressures, the range between 0.15-0.4 MPa is considered to perform the blowing out process in order to limit the gas speed and take into account possible pressure fluctuations. The analyses were fundamental to design a blowing-out system capable of satisfying the requirements of the different components belonging to the SPIDER Beam Source.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
