Direct reactor auxiliary cooling system for a molten salt nuclear reactor

An apparatus for delivering cooled fuel salt into a reactor core comprising:

• an exterior wall;
• an interior wall surrounding the reactor core and spaced apart from the exterior wall such that a plenum is formed between the exterior wall and the interior wall, the interior wall separating the reactor core from the plenum, the interior wall provided with a plurality of perforations penetrating the interior wall and permitting flow of nuclear fuel salt between the reactor core and the plenum;
• a top wall connecting the exterior wall and the interior wall;
• and
• a plenum inlet defined at least partially by the exterior wall and positioned opposite the top wall for receiving cooled nuclear fuel salt into the plenum, wherein the plenum has a tapered shape proximate the top wall, the plenum having a radial thickness that is greater at the plenum inlet than adjacent the top wall, and wherein the tapered shape of the plenum begins at a height above the plenum inlet.