I—11. The bubbling condenser containment system (Fig. I-4) in pressurized water reactors uses a concept for the suppression pool in which the high pressure steam-air mixture resulting from the conditions following a LOCA is directed through submerged tubes into pools of water. The steam is condensed in the bubbling condenser pools.

FIG. I-4. Schematic diagram of a bubbling condenser containment system for a pressu­rized water reactor: 1, containment; 2, upper containment volume (wet well); 3, lower containment volume (dry well); 4, bubbling condenser system (suppression pool); 5, suppression pool cooling system (not required if the heat capacity of the condenser system (4) is sufficiently large); 6, passive spray system; 7, active spray system; 8, filtered air discharge system; 9, liner.

I—12. The containment is a cylindrical concrete structure divided into three isolated volumes: the lower volume (dry well), which contains all the major components of the primary reactor coolant system, the bubbling condensers (suppression pools) and the main upper containment volume (wet well). Non­condensable gases (including noble gas fission products) that are driven into the bubbling condenser chambers are vented through openings into the main
upper containment volume. Radioiodine and other soluble or particulate fission products are trapped in the bubbling condenser water pools.

I—13. Open tanks located in the upper containment volume are connected through U tubes to water spray nozzles in the lower containment volume. During fast pressure transients in the containment system, the passive sprinkler system is activated by the pressure differences between the water inlet of the U tubes submerged in the tanks and the nozzle outlet. An active spray system, with an independent stored water supply, is used to provide the functions of both energy management and radionuclide management. When the water supply in the spray tanks is exhausted, a recirculation mode is initiated and water from the building sump is pumped through a heat exchanger and sprayed into the lower containment volume. After a few minutes, the pressure in the lower volume falls below atmospheric pressure and an inverse pressure differ­ential is created between the upper volume and the lower volume. Air is prevented from returning from the upper volume to the lower volume by hydroseals formed in the bubble tubes. Once the pressure in the lower volume has been reduced below atmospheric pressure, the leakage of radionuclides from it will cease.