Patent Number: 039473228
Section: description

DETAILED DESCRIPTION OF THE INVENTION The reactor pressure vessel 1 is substantially cylindrical with its axis vertical and within its core barrel 2, the reactor core (not shown) is positioned. The vessel has a top closure 3 normally bolted closed. An intercept ring 4 engages the periphery of the cover 3 and is held down by hooks 5 which pivot on hinges 6 secured to the upper portion of the cylindrical concrete containment 8 forming the pit in which the pressure vessel is positioned. The intercept ring and hook arrangement is disclosed and claimed by the Dorner et al U.S. application Ser. No. 315,932, filed Dec. 18, 1972. The bottom of the vessel 1 has a shoulder 9 at the periphery of its spherical bottom 10, and which is supported by the support arrangement 12 of the invention. Two identical steam generators 14 and 14' are connected with the upper portion of the vessel 1 by dual coolant pipes 15 and 15'. These pipes are in each instance divided by a horizontal partition so that the pipes provide coolant loops, respectively comprising hot legs 16 and 16' and cold legs 17 and 17'. The steam generators are of the type integrated or structurally combined with the main coolant pumps for the loops, the pumps being respectively shown at 20 and 20' driven by electric motors 21 and 21', the pumps being contained by concrete cylinders 22 and 22'. The substantially cylindrical steam generators extend upwardly from these motors and pumps within concrete containments 23 and 23' vertically held in compression by tie rods 24 and 24'. The arrangement 12 is shown on an enlarged scale by FIG. 2. Here, the short cylinder and cylindrical ring 26 is shown as being integral with the shoulder 9 of the vessel 1, although this ring 26 could be fixed to the periphery of the spherical bottom 10 of the vessel, by welding. This cylindrical ring 26 has substantially the same diameter as the vessel's bottom and is concentric with the axis of the vessel and its bottom. The bottom end of this ring 26 provides the inverted frusto-conical surface 27 which faces downwardly and is slidably supported by the upwardly facing upright frusto-conical surface 28 provided by a short cylinder or cylindrical ring 29 which is fixed as by welding to a flat steel base ring 30 resting on a shoulder 30a formed in the bottom of the concrete reactor pit and, therefore, capable of supporting the weight of the reactor vessel. In operation, if the diameter of the reactor vessel thermally increases, the surface 27 slides downwardly on the surface 28, and since at the same time the reactor vessel is elongated vertically, compensation for the vertical elongation is provided. The top portion of the vessel remains substantially unchanged as to its vertical position, vertical displacement of the pipes 15 and 15' being, therefore, avoided and eliminating vertical stressing. Furthermore, the pressure vessel, intercept ring 4 and hooks 5 may be designed so that when the vessel is at its normal operating temperature, the hooks 5 normally engage the intercept rings 4, thus placing the pressure vessel in compression between the hooks and its lower support points 9. The degree of this compression can be accurately calculated because via the present invention the vessel bottom is supported at differing heights which are dependent on the thermal expansion radially of the pressure vessel and which is, in turn, related to the vessel's vertical thermal expansion and contraction. As shown by FIG. 2, the supporting ring 29 may be made as a plurality of circumferentially interspaced segments 29b, this permitting air cooling of the lower cylindrical ring 29 and, in addition, reducing the risk that it might possibly change in diameter due to thermal expansion and contraction. The segments 29b should be strong and rigid and free from any spring action. The two surfaces 27 and 28 should retain their designed angularities at all times. Although the coolant pipes are relieved from vertical motion, they are still moved horizontally by the radial expansion and contraction of the vessel 1. Therefore, the steam generators 14 and 14' are supported on horizontally displaceable bearings 31 and 31' positioned as close as possible to the coolant pipes. This allows the steam generators to move in the axial or longitudinal directions of the coolant pipes and reduces stressing such as would occur if the steam generators were immovable horizontally. The pipe lines are provided with externally projecting shoulders 32 and 32' which are retained in annular recesses formed in the concrete construction 8 which has, of course, holes through which the coolant pipes extend to the steam generator. These recesses are formed around these holes. These recesses should provide enough space in the axial direction of the coolant pipes to permit their motion due to radial expansion and contraction of the vessel. However, the recesses should be proportioned so that in the event of a break in either coolant pipe or its connections between the shoulders and the vessel, the jet reaction will not result in excessive horizontal displacement of the steam generator having the pipe involved by the accident. Under normal conditions, the shoulders and their recesses serve to generally center the components of the installation.