Abstract: An improved single shell boiler is provided. The single shell boiler includes a closed vessel for containing a liquid heat transfer medium, with the liquid heat transfer medium having a surface. A first bundle of heat source tubes is located in the closed vessel and is adapted to be submerged within the liquid heat transfer medium for heating and vaporizing the liquid heat transfer medium. A second bundle of tubes is located in the closed vessel in a position which is adapted to be above the level of the liquid heat transfer medium within the vessel to receive heat by condensation of vaporized heat transfer medium on the second bundle of tubes. A condensate distribution plate is positioned between the first and second bundles of tubes. The condensate distribution plate is adapted to approximately evenly distribute condensate droplets released by the second bundle of tubes to break-up froth on the surface of the liquid heat transfer medium to enhance vapor release from the liquid heat transfer medium.

Abstract: A reactor vessel seal for temporarily sealing a reactor pressure vessel from a water-filled refueling canal above the reactor pressure vessel. The reactor vessel seal is installed in place of the removable reactor pressure vessel closure head for inspecting/servicing the reactor vessel. The reactor seal comprises a seal cap having a surface connected to a flange which is complementary to the upper flange of the reactor pressure vessel. A seal is located between the seal cap flange and the upper flange of the reactor pressure vessel. A lifting rig is connected to the seal cap for lifting the seal cap and placing it in position, with the seal cap flange in alignment with the reactor vessel upper flange, such that the seal located between the seal cap flange and the reactor pressure vessel upper flange is compressed by hydrostatic pressure from water in the water-filled refueling canal acting on the surface of the seal cap as water in the reactor pressure vessel is evacuated.

Abstract: A wall for a fluid container which includes a pair of vertically extending side beams between a pair of horizontally extending upper and lower beams. An arcuate panel is secured in the area defined by the vertically and horizontally extending beams. When the fluid container is filled iwth a fluidic material, fluid pressure applied to the arcuate inner surface deflects the panel downwardly in tension to force the upper beam downwardly to thereby compress the side beams between the upper and lower beams and thereby add significant static structural integrity to the wall.

Abstract: A radioactive fuel cell storage rack is comprised of structural elements including elements which are hollow and cruciform in section. Each leg of the cruciform structural element includes a neutron shield therein. The free end of the legs of the cruciform structural element converge so as to have an included angle of approximately 90.degree.. The rack is comprised of such cruciform elements as well as cooperating elements which are generally T and L shaped in section.

Abstract: A shell and tube type heater exchanger is disclosed for withstanding cyclic changes in temperatures of fluid without suffering failure by removing metal from the outer periphery of a tube sheet. The central portion of the tube sheet is a smooth arching contour mating with portions of the adjoining shell proximate to the tube sheet periphery without abrupt changes of section so that the surfaces blend with one another.