Repair work for liquefied carbon dioxide at a low-temperature storage tank (CE) in a steel mill was carried out. At the time, the main block valve below the safety valves was closed, while liquid CO2 remained in the tank. In addition, the heat source from the tank heater was still active. Therefore, in the tank, the temperature rose and pressure increased, and the low-temperature storage tank exploded. A vapor explosion of carbon dioxide occurred due to the rapid pressure drop.