Air cooled condenser and related methods

A system for removing thermal energy generated by radioactive materials comprising:

• an air-cooled heat exchanger defining a vertical axis and comprising a vertically oriented shell defining a cavity containing a plurality of heat exchange tubes fluidly coupled between a top fluid inlet header and a bottom fluid outlet header;
• the air-cooled heat exchanger comprising a heat rejection closed-loop fluid circuit comprising a tube-side fluid path, a coolant fluid flowing through the heat rejection closed-loop fluid circuit, the heat rejection closed-loop fluid circuit thermally coupled to the radioactive materials so that thermal energy generated by the radioactive materials is transferred to the coolant fluid;
• and
• the air-cooled heat exchanger comprising a shell-side fluid path inside the shell having a first air inlet formed through the shell, a second air inlet formed through the shell, and an air outlet formed through the shell, the first air inlet located at a first elevation, the second air inlet located at a second elevation, and the air outlet located at a third elevation, the second elevation greater than the first elevation and the third elevation greater than the second elevation, the air-cooled heat exchanger transferring thermal energy from the coolant fluid flowing through the tube-side fluid path to air flowing through the shell-side fluid path.