To miniaturize an apparatus, and to improve arrangement performance by reducing the air volume while maintaining the cooling function to atmosphere cooling equipment in a nuclear reactor containment vessel.

This cooling equipment cools an atmosphere in the reactor containment vessel A of a nuclear power plant. A cooling coil 2 of the cooling equipment arranged in the reactor containment vessel A is connected with a passage for supplying chilled water from an HECW refrigerator 11 of a normal-emergency chilled water system (an HECW system) arranged outside the reactor containment vessel A, and the cooled and dehumidified atmosphere is blown off by the cooling coil 2 into the reactor containment vessel A from an air blowing duct blowoff port 5 via an air blowing duct 4 by operation of an HECW air blower 1.