[en] This cooling is capable of controlling even heat outputs in the Megawatt range, which can occur for days after a core meltout, i.e. of removing the heat. A collecting tank for the core meltout is used for this purpose, which is connected from below as part of the containment surrounding the reactor. The tank made of relatively thin sheet steel, together with a lid forms a solid of revolution closed on all sides. A water space inside the concrete foundation supporting the containment surrounds the tank, and supports it by many supports, so that the tank has cooling water flowing round it. This is introduced via a lower inlet into the vertical foundation wall from a river or lake. Steam generated during heat removal is given off from an upper outlet via a short chimney. At a raised internal pressure inside the containment, any gases of vapours generated are diverted via safety valves or bursting diaphragms and a vertical pipeline into a horizontal annular blowdown line in the water container below the collecting tank and to the chimney. (orig./PW)