Preliminary study on Single-Phase Natural Circulation for the FINCLS Facility

In the FINCLS (Facility to Investigate Natural Circulation in SMART) design, a scaling method introduced by Ishii was adopted for conserving the thermal-hydraulic characteristics of the reference system, and then for avoiding distortion by the scale reduction. The volume and core power in the FINCLS facility were scaled down to 1/64 against SMART-ITL. FINCLS is a simplified test loop for comprehensive understanding of thermal-hydraulic phenomena in the primary loop of SMART-ITL. For realizing the scaled mass flow rate of natural circulation, adjusting total friction loss by applying an orifice with appropriate diameter is considered. Orifice diameter is determined as 9.0 mm from preliminary tests using MARS-KS code. MARS-KS simulations for totally three cases are carried out depending on the core power. The results of MARS-KS simulation clearly shows transient behavior and convergence to each steady-state in terms of pressure, temperature, PZR level, and mass flow rate.