Hutchinson Island Nuclear Containment Structure

The nuclear steel containment vessel at the Florida Power & Light Company plant was successfully post weld heat treated at the site. The entire heat treating operation was continuous for approximately 99 hr which includes holding time and controlled cool-down. The temperature reached was 1,150°F as required by the ASME code. The vessel is in the form of a 140 ft diam cylinder, 127 ft long with a hemi-ellipsoidal bottom head and a hemispherical dome. The total weight is approximately 4,500 tons. To accommodate the expected growth of 14 in. in the diameter during heat treatment, the vessel was supported on a series of A frame columns which were hinged at the top and bottom. These temporary supports were adjusted for equal loading. The necessary adjustment was determined by taking strain measurements in each leg after a portion of the vessel had been erected. The vessel was heated by eight oil-fired burners, each rated at 30,000,000 Btu per hr, four located in the bottom head and four approximately halfway up the cylinder.