Modeling critical flow in crack geometries using trace

The TRACE thermal hydraulic system code was used to predict subcooled critical flow for three sets of experiments employing crack geometries. The first experiment measured flow through slits in thin walled sections representative of defects in steam generator tubes. The second experiment consisted of critical flow rate tests in simulated circumferential cracks in large diameter piping. The final set of data measured critical flow through cracks in large diameter pipes produced by fatigue cycling. TRACE predictions for the first and second tests sets were in reasonable agreement with the experiments with calculated discharge coefficients ranging from 0.52 to 1.0. Flow rates were significantly over predicted for the third test set, which is likely due to geometric irregularities and higher surface roughness of these fatigue cracks compared to the prepared geometries of the other tests.