Abstract:
Under simulated accident conditions, tees in the primary coolant loop of a
Pressurized Water Reactor (PWR) can deviate from their original design purpose
and become separators that effectively remove core heat sink capacity. This method
of primary coolant removal is a phenomelogical subset of phase separation known
as liquid entrainment, whereby liquid is forced from its original path by the inertia
of the gas. A comprehensive literature review revealed common deficiencies in
previous studies. The Westinghouse AP600 advanced reactor design was chosen to
assess the validity of entrainment models. Following a systematic scaling analysis
of the prototypic design a model separate effects test was proposed and constructed
at Oregon State University. Just under 100 tests were run to fill the deficiencies
found in the literature review. New data from the Air-water Test Loop for
Advanced Thermal-hydraulic Studies (ATLATS) could not be predicted by
published correlations. A new theoretical model for predicting liquid entrainment
onset and steady state entrainment was developed. Comparison with all available
data shows a marked improvement for predicting the mass flow rate out the vertical
branch.
