Close-fitting shield doors with sculptured edges

The US Department of Energy has contracted with Fluor Technology, Inc. for design and engineering of a facility to begin reprocessing fuel from the reactors at Hanford, Washington. Within the facility, a 15-cm (6-in.)-thick, steel shield door is needed to close an opening 4.3 m (14 ft) high x 8.2 m (27 ft) wide. Two cranes and a centrally located monorail hoist must pass through the opening. The door weighs about 41,000 kg (45 ton), and passage of the hoist will be the most frequent cause for opening the door. These two factors essentially mandated a three-piece door, which allows for using commercially available chain hoists to raise and lower the individual door sections. Normally, there is a 187-Pa (0.75-in. water gauge) pressure differential across the door, and minimal air leakage is essential. Stepped, mating edges between sections and along the adjacent concrete structures are typical with such doors, but so are significant gaps (and air leaks) around the edges. Gaps are needed to preclude frictional jamming between edges as a section is lowered. The challenge was to conceive a method to produce near-zero gaps and preclude jamming without involving impractically tight tolerances. The chosen method was to place trapezoidally shaped, steel gaskets on the door-section edges and on the mating concrete surfaces. The concept is described