Preliminary results of the experimental campaign conducted on the dynasty natural circulation loop

The study of the physical phenomenon of natural circulation is of importance for the development of passive safety systems and GEN-IV nuclear reactors as the Molten Salt Fast Reactor (MSFR), characterized by internal heat generation. To this aim, the DYNASTY natural circulation loop has been built to study natural circulation in presence of a distributed heat source and to validate analytical and numerical models.

This paper is aimed at providing the results of an experimental campaign performed on DYNASTY using water as fluid. Different heating configurations of the facility were tested, each using different legs of the facility as the heat source. The influence of the cooler fan speed on the experimental behavior was also considered. The experimental results collected are the mass flow rate inside the loop, and four fluid temperatures measured by thermocouples at the beginning and at the end of the vertical and horizontal sections.

The results show the transient evolution of the system, gradually increasing the heating power starting from a zero-power condition up to the achievement of a steady state at maximum power. The effect of the velocity of the fan is remarkable at low fan velocity. Vertical configurations are almost symmetric, being just different in the direction of the fluid motion. Experimental evidence after the shutdown of the heaters pointed out some monodirectional oscillations in both vertical cases before the mass flow rate settles to zero values.