Patent Number: 039909417
Section: summary

BACKGROUND OF THE INVENTION A nuclear reactor pressure vessel installation is disclosed by the U.S. Keller Application Ser. No. 367,955, filed June 7, 1973, as comprising a pressurized-water reactor pressure vessel surrounded by the wall of a biological shield which forms a space between it and the vessel. Vertical steel beams, each formed in part by two vertical steel channels, are circumferentially interspaced at relatively large distances around the periphery of the reactor pressure vessel to support the latter, but while forming vertical passages of extensive cross-sectional area to which the pressurized-water coolant can escape upwardly with little resistance, in the event the pressure vessel ruptures. With this relatively large circumferential interspacing of the vertical beams, the wall of the pressure vessel remains substantially unsupported throughout each area between the interspaced beams. However, upwardly extending spaces are formed having the advantage that they may be used for the upward flow of air coolant between the pressure vessel wall and the concrete wall to protect the latter against excessive heating. SUMMARY OF THE INVENTION The object of the present invention is to provide an installation having for practical purposes the same possibility for upward flow of a coolant, such as air, between the vessel and the concrete wall, while at the same time providing for the radial support of the pressure vessel wall in a manner that is substantially circumferentially continuous so that the risk of such a pressure wall rupture is very greatly reduced. According to the invention, the heat insulation layer, which is, of course, made of pressure-resistant concrete, such as cast concrete blocks, surrounds the pressure vessel wall in the circumferentially continuous manner as before. Also, vertical steel beams are positioned between the heat insulation layer and the concrete wall formed by the biological shield. However, the difference is that the steel beams, which have webs and flanges characteristic of rolled steel structural shapes, are positioned circumferentially very close together with the flange edge of each beam engaging the flange edge of each adjacent beam so that a continuous steel wall circumferentially surrounds the heat insulation in contact therewith, and a corresponding steel wall engages the concrete wall with the webs of the beams functioning as vertically continuous struts. Preferably the beams are formed by conventional structural steel H or I beam shapes, although channel shapes may conceivably be used. With the first-mentioned shapes, the flanges which engage the heat insulation can be butted against each other to provide the heat insulation layer, and, therefore, the pressure vessel wall, with a circumferentially and vertically continuous steel wall. The usual pressure vessel is generally cylindrical with its heat insulating layer being correspondingly shaped, the contour of the concrete wall of the biological shield being correspondingly contoured. This means that the beam webs are inherently radially arranged so that their flanges which engage the concrete wall are slightly interspaced circumferentially. Due to the diameter of any reactor pressure vessel of what would be currently considered to be provided by a reactor of high power, the flange interspacing around the concrete wall is very slight. The vertical coolant channels formed between the beam webs can almost be considered to be circumferentially continuous, being interrupted only by the flanges which are relatively thin. When air or other coolant is passed upwardly between the beam flanges, a steel skin can be interposed between the flanges and the heat insulation layer, to prevent the leakage of the cooling air through the heat insulation layer to the pressure vessel wall, keeping in mind that the heat insulation layer is ordinarily formed by large concrete blocks which possibly provide leakage paths via their abutting edges.