Key Aspects of the Safety Study of a Water-Cooled Fusion DEMO Reactor

Abstract

Key aspects of the safety study of a water-cooled fusion DEMO reactor is reported. Safety requirements, dose target, DEMO plant model and confinement strategy of the safety study are briefly introduced. The internal hazard of a water-cooled DEMO, i.e. identification of hazardous inventories, identification of stored energies that can mobilize these hazardous inventories and identification of accident initiators and scenarios, are evaluated. It is pointed out that the enthalpy in the first wall/blanket cooling loops, the decay heat and the energy potentially released by the Be-steam chemical reaction are of special concern for the water-cooled DEMO. An ex-vessel loss-of-coolant accident (ex-VV LOCA) of the first wall/blanket cooling loop is also quantitatively analyzed. The integrity of the building against the ex-VV LOCA is discussed.

Analysis on ex-vessel loss of coolant accident for a water-cooled fusion DEMO reactor

“…The pressure suppression tank is pressurized by released air and vapor that cannot be condensed. 5. Rupture disks at relief pipes between the suppression tank and upper tokamak hall are opened.…”

“…In the activity, safety studies have also been carried out [4,5]. This is because the DEMO fusion reactor has both some radioactive materials and energy potential to release these materials outside reactor buildings.…”

“…This is because the DEMO fusion reactor has both some radioactive materials and energy potential to release these materials outside reactor buildings. To prevent emission of these radioactive materials to environment, the DEMO fusion reactor has been considered to set two confinement boundaries [5]. First boundary is vacuum vessel and vacuum vessel pressure suppression system, and second boundary is tokamak building, detritiation system, and stack.…”

“…In response to this accident, preliminary accident analysis was carried out [5]. The results indicate the pressure increase in reactor building is rapid, and the maximum pressure is 144 kPa if the building volume is 380,000 m 3 .…”

Parametric explorative study of DEMO galleries pressurization in case of ex-vessel LOCA

“…In this context, an explorative parametric assessment of variables relevant for confinement design can help at better framing the option design space. Recently ex-vessel LOCA assessments for DEMO have been presented in order to provide early-feedback on possible problems emerging from proposed design solutions especially for blanket coolant inventories [1,2]. The goal of the present work is to investigate the pressurization * Corresponding author.…”