What are some of the differences in the NuScale design?
First, the reactor vessel is integrated into the containment vessel and the steam generators are integrated into the reactor vessel. Instead of the large, reinforced concrete dome-shaped containment buildings seen at existing plants, the NuScale containment is a steel cylinder that is 65 feet long and 14 feet in diameter. The steel reactor vessel fits inside the containment vessel. There are two “helical coil” steam generators within the reactor vessel. Second, instead of motor-operated pumps, the NuScale reactor system uses natural circulation – a convection process – to circulate water through the reactor. The NuScale design eliminates concerns about a Loss of Coolant Accident (LOCA) in other designs that could result from a break in the large pipes that connect the reactor to steam generators. In addition, there are no pumps on the reactor system that require an emergency electrical power supply for cooling if power is lost to the site.
