Patent Number: 039390381
Section: claims

1. A pressurized-water nuclear reactor including a pressure vessel having a substantially cylindrical side wall and a substantially hemispherical bottom wall above which a core vessel is positioned by its top, with its lower end spaced above this bottom wall, and means extending upwardly from the latter towards said lower end for intercepting said core vessel if it accidentally falls, said pressure vessel having a cover and pressurized-water coolant connections; wherein the improvement comprises said means being formed by a structural metal framework inside of said vessel and supported by said bottom wall at a plurality of interspaced positions, said framework extending upwardly until at least adjacent to the core vessel's said lower end, at least some of said interspaced locations being adjacent to the peripheral portion of said bottom wall, said framework being made of ductile metal and having upper portions proportioned to deform beyond the elastic limit of the metal and absorb the shock of intercepting said core vessel when it falls. 2. The reactor of claim 1 in which said framework includes an annular series of substantially vertical interspaced columns extending upwardly from said peripheral portion. 3. The reactor of claim 2 in which said framework includes a central substantially vertical column extending upwardly from substantially the center of said bottom, and struts extending laterally from this central column to said annular series of columns and positioning them on said peripheral portions. 4. The reactor of claim 3 in which said peripheral series of columns are formed by substantially flat plates positioned in radial planes with respect to said central column and are interconnected by a ring. 5. The reactor of claim 3 having means connecting with said bottom wall for tensioning said central column downwardly. 6. The reactor of claim 3 in which said core vessel has a downwardly extending flange and said framework includes a ring connected with said annular series of columns and positioned thereby at least partly inside of said flange and peripherally adjacent thereto. 7. The reactor of claim 3 in which all of said columns are plates made of ductile metal and are upwardly tapered to provide gradually reducing cross-sectional areas for shock-absorbing deformation beyond the metal's elastic limit when intercepting said core vessel if it falls. 8. A pressurized-water nuclear reactor including a pressure vessel having a substantially cylindrical side wall and a substantially hemispherical bottom wall above which a core vessel is positioned by its top, with its lower end spaced above this bottom wall, and means extending upwardly from the latter towards said lower end for intercepting said core vessel if it accidentally falls, said pressure vessel having a cover and pressurized-water coolant connections; wherein the improvement comprises said means being formed by a structural metal framework inside of said vessel and supported by said bottom wall at a plurality of interspaced positions, said framework extending upwardly until at least adjacent to the core vessel's said lower end, at least some of said interspaced locations being adjacent to the peripheral portion of said bottom wall, said framework including a plurality of substantially vertical interspaced columns extending upwardly from said locations adjacent to said peripheral portion, a central substantially vertical column extending upwardly from substantially the center of said bottom, and struts extending laterally from this central column to said plurality of columns and positioning them on said peripheral portions.