Scaling considerations for FLECHT-SEASET

The NRC/EPRI/W FLECHT-SEASET systems effects test facility was originally designed to study low pressure reflood PWR systems behavior. The facility was modified to also study single-phase, two-phase, and reflux condensation natural circulation transients which are more typical of a high pressure PWR small break LOCA or operational transient. The question of how to design the scaled facility to study each of these diverse conditions had to be addressed. The traditional scaling approaches such as linear, power to volume, volumetric, and dimensionless numbers, were examined and evaluated for each test before power to volume was selected. The thermal-hydraulic phenomena for each type of test was reviewed and the primary driving forces for each test identified and preserved. Since the pressure which was to be simulated in the two experiments was significantly different, two-phase flow scaling approaches were examined, particularly for the reflux condensation natural circulation tests. The paper will describe the scaling basis chosen for each test series and will highlight where the scaling compromises were and how they were technically resolved