Comparisons of RELAP4/MOD6 with core blowdown data

The independent verification of the RELAP4/MOD6, Update 3 computer code for a pressurized water reactor core during the blowdown phase of a loss-of-coolant accident is described. Calculations of RELAP4 core component models were compared with data from Semiscale and Thermal-Hydraulic Test Facility blowdown experiments. Measured boundary conditions were applied to the component models. The sensitivity of the calculated results to core phase slip model, core model nodalization, uncertainty in measured boundary conditions, critical heat flux correlation, and film boiling correlation was determined