Construction of the containment building began on August 22, 1960 as curved segments of steel 7/8 of an inch thick began to form a perfect sphere, the plant’s signature profile, 130 feet in diameter of which 27 feet were below ground. This is the structure that housed the reactor vessel, the spent fuel pool, and the 100-ton, 40-foot long steam drum to which a superheated 500-degree F. water/steam combination was sent from the boiling water reactor. There they were separated, the steam going on to the turbine in the building next door, the water circulated back to the reactor.