The flooding pools are equipped with active coolers. If the active cooling fails, the 3600 m3 pool will not start to evaporate for twelve hours. During a failure the pressure in the containment is increased and the heat is transferred by four containment cooling condensers into the upper shielding pool (see Fig. XI-1, XI-2 and XI-4). Each condenser is able to transfer up to 5.5 MW at a pressure of 0.25 MPa. Each condenser consists of 124 finned tubes arranged in two layers (design state 1998). The tubes have a length of 4 m, an inner diameter of 32 mm and a tube wall thickness of 3 mm. The tubes are arranged with a twelve degree incline. In addition, a second version of the cooling condenser was designed to remove non condensable gases.

FIG. XI-4. Working principle of the containment cooling condenser.