Project design progress on plasma and outer vessel exhaust gas system based on LOCA safety analysis of W7-X stellarator

Wendelstein 7-X (W7-X) is a fully optimized low-shear stellarator and shall demonstrate the reactor potential of this fusion plant. It is presently under construction at the Greifswald branch institute of IPP. The cryostat of W7-X stellarator has a torus shape which consists of a plasma vessel as an inner vessel, the outer vessel and the ports, which connect the plasma vessel (PV) with the outer vessel (OV). In operating mode several postulated hazard events which could occur on W7-X stellarator were identified. A set of actions were initiated, in order to mitigate or minimize the possible damaging consequences especially for both main W7-X vessels (OV and PV). The document presents the requirements of the exhaust gas safety systems currently under design for both vessels with overpressure protections working in failure mode.