Patent Number: 039473228
Section: summary

BACKGROUND OF THE INVENTION A pressurized-water reactor pressure vessel has coolant pipes radiating from its upper portion and connecting with steam generators. With temperature changes, the vessel thermally expands and contracts. To prevent such thermally induced motion from unduly stressing the coolant pipes, the vessel may be supported adjacent to the pipes which radiate from its upper portion. For greater support it is desirable to also support the vessel via its bottom, but this introduced the problem that if the vessel is supported mainly via its bottom its vertical thermal expansion and contraction motions displace the coolant pipes and place undesirable stresses on them and their connections with the vessels and the steam generators. SUMMARY OF THE INVENTION The object of the present invention is to support the vessel entirely or it least mainly by way of its bottom without introducing such stressing due to the thermal vertical expansion and contraction of the vessel. According to the invention, the bottom of the vessel has a short cylinder fixed to it and providing an inverted frusto-conical surface pointing downwardly, this cylinder and its surface being concentric with the axis of the vessel and expanding and contracting radially with radial expansion and contraction of the vessel. This surface slidably rests on an upright frusto-conical surface provided by a short cylinder of the same diameter as the ring fixed to the vessel, and which rests on a suitable foundation which can be provided in the bottom of the usual concrete pit in which the vessel is positioned. The two surfaces are concentric and their angularities are the same. The result of the above is that when the vessel thermally expands vertically and, therefore, also radially, the diameter of the cylinder fixed to the vessel's bottom changes, and by cam action the two surfaces provide vertical motion. The angularity of the two surfaces can be made so that as the vessel thermally expands its bottom moves downwardly and when it contracts vertically, its bottom moves upwardly, so that there is no motion at the vessel's top or upper portion from which the coolant pipes extend. This permits the coolant pipes to remain immovable vertically and reduces or eliminates their stressing previously described. When the coolant pipes extend horizontally and substantially straight between the vessel and the steam generators, the stressing of the pipes due to the radial expansion and contraction of the upper portion of the vessel, can be greatly reduced by mounting the steam generators so that they can slide horizontally in the direction the pipes horizontally expand and contract. Other features will be understood from the following.