Investigation of two-phase flow regimes in LOFT piping during loss-of-coolant experiments

The two-phase flow regimes present in the Loss-of-Fluid Test (LOFT) facility primary coolant piping during nonnuclear Experiments L1-1 through L1-4 have been investigated. The flow regimes were determined from density profiles calculated by a computer program using data from the five three-beam gamma densitometers employed in LOFT. The LOFT flow regime data were compared with two-phase flow transition theory data to evaluate the validity of using steady state flow maps to predict flow regimes in the LOFT primary coolant piping during a blowdown transient. The LOFT data were compared with flow regime data from the Semiscale Mod-1 facility, which is approximately 1/30 the size of LOFT, to gain insight into the effects of scale.