Patent Number: 039909417
Section: description

DETAILED DESCRIPTION OF THE INVENTION Having reference to the above drawing, the pressurized-water reactor installation involved may have a power rating in the area of 1,200 MWe. Therefore, the pressure vessel 1 should be provided with very effective rupture protection. Consequently, the pressure vessel 1 is made from thick-walled steel annular sections welded edge-to-edge to form a vertical cylindrical vessel having its top closed by a removable head 2 overlayed by reinforcing cover 4 held down via its periphery by an intercept ring 5 firmly secured when the pressure vessel thermally expands vertically, by self-locking hooks 6 pivoted at 7, the biological shield forming the reactor cavity or pit 10 by its concrete wall 12 and by its steel reinforced concrete wall 12 to the top of which the hook pivots 7 are anchored, vertical steel bars 13 extending through the concrete for vertical reinforcement. The annular space between the concrete wall and the wall of the vessel 1 is shown at 15 while the heat insulating and pressure-resistant concrete wall formed by the large cast blocks is shown at 16, this layer directly contacting the outside of the pressure vessel wall when the latter is thermally expanded radially by operation of the reactor. This concrete layer 16 may occupy about two-thirds of the width or thickness of the annular space 15. The steel beams previously described are shown at 17 as forming via their abutting flange edges what is substantially a cylinder made of steel. In this instance, I-beam shapes are used with their flanges 18 against which the heat insulating layer 16 presses during reactor operation, forming a circumferentially continuous steel wall transmitting compression to the other flanges of the beams which press against the concrete wall of the biological shield to form there also what is, as a practical matter, another continuous steel wall. When the reactor is in operation, the heat-insulating layer and beams are under compression in the radial direction of the vessel 1 with the concrete wall of the biological shield providing the reaction, the pressure vessel thus being provided with zero-travel restraint. The parts are proportioned so that when the reactor is cold and thermally contracted, the blocks forming the heat-insulating layer can be pulled upwardly to form a space for external pressure wall inspection. A sheet steel skin 19 is shown as being fastened to the innermost flanges of the beams so that the air coolant ducts 22 formed between the beam webs are provided with the sealing previously referred to. The coolant may be introduced via a duct 24 to an annular manifold space 25 extending peripherally around and open to the bottom ends of the vertical air coolant ducts 22, the air rising upwardly in the direction of the arrow 26 adjacent to the coolant nozzles 27 which radiate from the upper end of the vessel 1, baffles 28 diverting a portion of the upwardly flowing coolant, as by annular ducts 28, so that some of the air coolant flows circumferentially around the nozzles and outwardly in their axial directions, the balance of the air coolant leaving via the tops of the ducts 22 providing the advantage of cooling the steel hooks 6. To provide for a coolant flow, the steel support ring 14, on which the bottom of the pressure vessel is supported against downward motion, is provided with radial ducts 14a. A hemispherical layer 32 of heat-insulating concrete is positioned against the hemispherical bottom 30 of the pressure vessel 1, and is supported via steel beams 33 by the bottom of the biological shield cavity, these beams extending radially and necessarily being curved, but to some extent in the manner described before, providing coolant ducts which may be supplied with air via a duct 34 extending to the center of the hemispherical nest of steel beams.