Earthquake-proof mounting support for control rod drives of nuclear reactors having a generally cylindrical reactor pressure vessel formed with a convex wall at least at one end thereof and including control rods with control rod drive shafts coupled thereto and mounted so as to be movable in axial direction thereof within tubular drive housings extending pressure-tightly through the end convex wall and sealed against the outside, the tubular drive housings comprising tube member forming respective feed-through passageways for the control rod drive shafts, the tube members having respective portions thereof extending with respectively varying lengths outside and beyond the convex wall to a given horizontal plane, and a support grid formed of a plurality of grid bars articulatingly connecting the tube members at respective free ends thereof outside the convex wall, respectively, to one another.