Wet storage facility for nuclear fuel

An autonomous impact resistant wet storage facility for spent nuclear fuel, the facility comprising:

• a longitudinal axis;
• a concrete base mat defining a substantially horizontal operating deck, the base mat disposed in soil having a grade and extending for a depth below grade;
• a plurality of substantially vertical concrete perimeter walls supported by the base mat, the perimeter walls extending upwards from the operating deck and rising above grade;
• a concrete roof spanning across the perimeter walls and collectively forming an enclosed building with the perimeter walls and base mat;
• a spent fuel pool disposed in the building and recessed in the base mat below the operating deck for storing nuclear fuel assemblies, the spent fuel pool containing water for cooling the fuel assemblies;
• a cask pit recessed in the base mat below the operating deck and formed integrally with the spent fuel pool, the cask pit located adjacent the spent fuel pool and having a second depth;
• a vertically elongated fluid passageway formed through the base mat between the cask pit and spent fuel pool, the passageway extending vertically through the operating deck, wherein the cask pit is in fluid communication through the passageway with the spent fuel pool wherein pool water is flowable between the spent fuel pool and cask pit;
• an isolation gate movably disposed in the passageway which operates to fluidly isolate the cask pit from the spent fuel pool, the gate movable between an open position in which the passageway is unobstructed so pool water can flow between the spent fuel pool and cask pit, and a closed position in which the passageway is obstructed so pool water cannot flow between the spent fuel pool and cask pit;
• a passive cooling system for cooling the water in the spent fuel pool, the cooling system comprising an internal immersion heat exchanger submerged in the spent fuel pool and an external air cooled heat exchanger located outside the perimeter walls, the immersion heat exchanger located below grade and the air cooled heat exchanger located above grade creating an elevation difference;
• a closed flow loop formed between the immersion and air cooled heat exchangers, the flow loop containing a circulating heat exchange working fluid;
• wherein the working fluid circulates by natural gravity driven flow between the immersion and air cooled heat exchangers wherein the spent fuel pool is cooled in the absence of electric power to the facility;
• wherein the air cooled heat exchanger is disposed inside a cavity of a vertically elongated steel reinforced concrete silo, the silo attached to one of the plurality of substantially vertical perimeter walls of the facility;
• and
• wherein the silo includes a vertically extending semicircular sidewall which extends below grade, and opposing ends of the semicircular sidewall are attached to the one of the plurality of substantially vertical perimeter walls.