Systematic analysis of a station blackout scenario for APR1400 with test facility ATLAS and MARS code from scaling viewpoint

To quantitatively study the scaling distortions in the scaled-down test facility ATLAS (Advanced Test Loop for Accident Simulation), two models – an ATLAS model simulating the ATLAS facility and an APR1400 (Advanced Power Reactor 1400 MWt) model representing the prototype APR1400 are employed. Particularly, the ATLAS model is validated against the station blackout test SBO-01 performed at the ATLAS facility, a Full-Pressure and Reduced-Height (FPRH) test facility with respect to the APR1400. With the well validated ATLAS model, the sensitivity analysis of the system heat loss on the SBO transient is performed. It was found that the heat loss in the ATLAS model has a large effect on the SBO transient. In addition, the ARP1400 model is also used to study the effect of the heat loss on the SBO transient. The results show that the heat loss in the APR1400 has a negligible effect on the SBO transient. Furthermore, the SBO transients of the APR1400 and ATLAS models are compared to see whether any other scaling distortion exists in the geometrical and thermal-hydraulic test conditions of the ATLAS facility. The comparison indicates that the scaling distortions of the heat loss and the SG fluid inventory exist in the ATLAS, which is then confirmed by the scaling analysis. These analyses are expected to provide useful evidences and references for scaling analysis, conducting experiments in small-scale test facilities, designing new safety systems and improving the accident management system.