【Aim】The aim of this study was to evaluate the safety and feasibility of using the NCV-3 automatic blood return system (Nippro, Tokyo, Japan) in a blood circuit for dialysis during a power outage. 【Method】The time taken to return 300 mL of saline (as a substitute for blood) at 100 mL/min using the NCV-3 automatic blood return system or the conventional manual method was measured 8 times by 4 trained medical engineers in a crossover simulation study. 【Results & Discussion】In the first trial, the time required to achieve saline return using the NCV-3 automatic blood return system was significantly shorter than that required when the conventional manual method was employed (222.0±5.0 sec vs. 344±14.1 sec, p=0.0005). The time required to achieve saline return using the conventional manual method gradually decreased according to the learning curve, and the time recorded in the eighth and final trial was 236.5±9.6 sec (p=0.054 vs. the automatic blood return system). The NCV-3 automatic blood return system might help to reduce the workload of staff in the event of an emergency power outage. 【Conclusion】 Our simulation study proved the safety and feasibility of using the NCV-3 automatic blood return system in a blood circuit during a power outage.