INTEGRATED ASSESSMENT OF THERMAL HYDRAULIC PROCESSES IN W7-X FUSION EXPERIMENTAL FACILITY

摘要

Energy received from the nuclear fusion reaction is one of the most promising options for generating large amounts of carbon-free energy in the future. Nowadays world needs new, cleaner ways to supply our increasing energy demand, as concerns grow over climate change and declining supplies of fossil fuels. Power plants based on nuclear fusion reaction would have a number of advantages. However in this technology existing physical and technical problems are complicated. The problems, related to the safety of humans and surrounding environment are occurring in addition to the all physical and engineering issues, given to nuclear fusion devices. Several experimental nuclear fusion devices around the world have been already constructed and a few are under construction. However, the processes in cooling system of in-vessel components, vacuum vessel and pressure increase protection system of nuclear fusion devices are not widely studied. The most amount of radioactive materials is concentrated in the vacuum (plasma) vessel of the fusion device, but this component cannot withstand to a pressure even slightly above atmospheric. Any rupture of cooling system pipe of in-vessel components, leading to ingress of water in the vacuum vessel may lead to sharp pressure increase and possible damage of vacuum vessel. Therefore, systematic and detailed experimental and numerical studies, regarding the thermal-hydraulic processes in cooling system and vacuum vessel, are important and relevant. In this article the study of thermal-hydraulic processes in cooling systems of in-vessel components, vacuum vessels and pressure increase protection system of nuclear fusion devices will be provided. "Ingress of Coolant Event" experimental facilities were modelled using RELAP5 program code and the calculation results were compared with the experimental data. Using the experience gained from the modelling of "Ingress of Coolant Event" experiments, the numerical model (including cooling system of in-vessel components, vacuum vessel and pressure increase protection system) of Wendelstein 7-X experimental fusion device was developed. The integrated analysis of the thermal-hydraulic processes occurring in the cooling system of in-vessel components, vacuum vessel and pressure increase protection system of Wendelstein 7-X experimental fusion device was performed in the case of loss of coolant. The provided analysis showed that RELAP5 code is capable of modelling the processes in cooling systems of in-vessel components, vacuum vessels and pressure increase protection system of nuclear fusion devices in the case of loss of coolant event. Integrated analysis of W7-X device in the case of loss of coolant event showed that the design of facility prevents the failure of vacuum vessel.