Comparative Study of Station Blackout Counterpart Tests in APEX and ROSA/AP600

A comparison is presented between station blackout tests conducted in both the Advanced Plant Experiment (APEX) facility and in the modified Rig of Safety Assessment (ROSA/AP600) Large-Scale Test Facility. The comparison includes the depressurization and liquid-level behavior during secondary-side blowdown, natural circulation, automatic depressurization system operation, and in-containment refueling water storage tank injection. Reasonable agreement between the test results from APEX NRC-2 and ROSA/AP600 AP-BO-01 has been observed with respect to the timing of depressurization and liquid draining rates. This indicates that the reduced height and pressure scaling of APEX preserves the sequence of events relative to the full-height and pressure ROSA/AP600.