houses the reactor, pressurizer, reactor coolant pumps, steam generator and other equipment or piping containing reactor coolant. The containment building is an airtight structure made of steel-reinforced concrete. The base slab is approximately 9 feet thick; the vertical walls are 3 3/4 feet thick; and the dome is 3 feet thick.

A containment building, in its most common usage, is a steel or concrete structure enclosing a nuclear reactor. It is designed to, in any emergency, contain the escape of radiation despite pressures in the range of 60 to 200 psi ( 410 to 1400 kPa ). The containment is the final barrier to radioactive release, the first being the fuel ceramic itself, the second being the metal fuel cladding tubes, the third being the reactor vessel and coolant system.