Conceptual Design and Feasibility Test of Two-Phase Hydrogen Thermal Siphon System of CNS in CARR

Conceptual design of the hydrogen system of cold neutron source （CNS） in China Advanced Research Reactor （CARR） was proposed, and feasibility test was carried out. In order to determine the void fraction in neutron moderator, the circulation ability of the two-phase hydrogen thermal siphon system, and the structure of components of the CNS, the mockup test was performed using Freon-113 as working fluid. To obtain the modeling criterion so that the above experimental results can be applied to the design of CARR, the bubble rising velocities in different liquids were investigated to study the effects of physical properties such as density, viscosity and surface tension on bubble rising velocity, void fraction and circulation ability.