Analysis of ECC bypass data

Data from small scale tests investigating the delivery of emergency core cooling water into the lower plenum of a pressurized water reactor during a loss-of-coolant accident have been analyzed. A statistical analysis of data trends has been performed and the data represented in correlational form. The effects of test pressure are well understood and all pressure effects observed are accounted for by steam properties. Uncertainty exists concerning how to extrapolate these small scale test results to full scale. However, small scale tests indicate that a constant momentum flux scaling of the hydraulics may be more appropriate than the traditional J* scaling. Evidence also exists which suggests that condensation effects may be increasing in importance as scale size increases