This device comprises a spray assembly (40) for spraying fluid into the chamber, and a fluid feed pipe (42) intended to feed fluid to the spray assembly (40). It comprises a fluid-distributing intermediate receptacle (46) positioned between the feed pipe (42) and the spray assembly (40), the intermediate receptacle (46) being connected upstream to the feed pipe (42) and comprising a fluid-evacuating sidewall (52) delimiting through orifices (60) connected to the spray assembly (40). It comprises at least one pipe (44A to 44D) for evacuating fluid towards the chamber (19) and projecting into the intermediate receptacle (46) opposite the sidewall (52).

A pressurized water nuclear reactor (PWR) includes a pressure vessel having a lower portion containing a nuclear reactor core comprising a fissile material and an upper portion defining an internal pressurizer volume. A condenser is secured to, and optionally supported by, the upper portion of the pressure vessel. A condenser inlet is in fluid communication with the internal pressurizer volume. A heat sink is in fluid communication with the condenser such that the condenser operates as a passive heat exchanger to condense steam from the internal pressurizer volume into condensate while rejecting heat to the heat sink. A condenser outlet connects with the pressure vessel to return condensate to the pressure vessel. A single metal forging having a first end welded to the pressure vessel and a second end welded to the condenser inlet may provide the fluid communication between the condenser inlet and the internal pressurizer volume.