Pressure surge in Wendelstein 7-X experimental stellarator facility

Abstract

Abstract Fusion is the energy production technology, which could potentially solve problems with growing energy demand of population in the future. Wendelstein 7-X (W7-X) is an experimental stellarator facility currently being built in Greifswald, Germany, which shall demonstrate that in the future energy could be produced in such type of fusion reactors. Lithuanian energy institute (LEI) in the frames of European Fusion Development Agreement (EFDA) program is cooperating with Max Planck Institute for Plasma Physics (IPP, Germany) by performing safety analysis of fusion device W7-X. In this paper the consequences of potential water hammer effects were analysed only for the case, when the plasma vessel is operating in the “baking” mode. “Baking” is the mode of facility operation during which the plasma vessel structures are heated up to 150°C in order to release absorbed gases from the surfaces and to pump them out of the plasma vessel before plasma operation. For the analysis the thermal-hydraulic model of target (torus) modules cooling / heating systems in W7-X facility was developed using RELAP5/Mod3.3 code. The performed analyses showed that the pressure pulsations in pipelines of cooling / heating systems are possible only in case of very fast closure of automatic valves in torus modules inlets and check valves in torus modules outlets. The maximum dynamic loading to cooling / heating systems pipelines due to such valves activations is in the range 0.12–0.28 MPa. Such dynamic load is insignificant and integrity of pipelines remains not violated. The pressure surge in pipeline connecting torus module in case of erroneous closure of automatic valve is eliminated due to operation of check valve on pipeline in torus module outlet.