In a hypothetical loss of coolant accident, a guillotine break of a coolant line occurs outside the vacuum vessel, that causes instantaneous loss of cooling of breeding blankets in one sector of the tokamak. Due to the material activation, residual heat must be dissipated from the reactor even after the reactor shutdown. With additional cooling functions, potential damage to the in vessel components of the reactor due to overheating can be prevented. For this purpose, dry air is injected into the vacuum vessel to facilitate convective cooling of the affected components.
A numerical analysis of the cooling of the affected sector of the DEMO reactor has been performed, using the ANSYS Fluent computational fluid dynamics software. A conjugate heat transfer model for fluids and solids was used, with the inclusion of thermal radiation. The analysis showed that natural convection of the air provides sufficient cooling of the breeding blankets. The temperature of the blankets initially rises, then the system starts to cool down.
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