Abstract: A method for safeguarding discharge of residual heat from a nuclear power station reactor upon a lowered filling level in a primary circuit of a reactor cooling system, includes initially shutting down the reactor and running through an initial cooling and pressure reduction phase in the primary circuit. Then an aftercooling system is cut in for taking over heat discharge from the primary circuit, when heat discharge is no longer guaranteed by a steam generator plant. Then complete pressure relief and a lowering of the filling level in the cooling system to a mid-loop level of a main coolant conduit take place. A coolant reservoir is present for a required refilling of the primary circuit and aftercooling system.

Abstract: A nuclear reactor, in particular a pressurized water reactor, has a containment, a containment shell surrounding the containment and a concrete construction of a reactor building surrounding the containment shell. A heat dissipation system for the nuclear reactor includes a sump volume disposed in a lower region of the containment shell for receiving coolant. A sump cooler is disposed inside the sump volume, has cooling tubes with a primary side and a secondary side and has feed and return lines. The primary side of the cooling tubes is covered at least when the sump volume is largely filled with coolant. An intermediate cooler has a tertiary side and is connected through the feed and return lines of the sump cooler to the secondary side of the cooling tubes. A heat sink is disposed outside the reactor building and is connected to the intermediate cooler on the tertiary side.

Abstract: A pressurized water reactor residual heat extraction system uses the secondary cooling circuit to extract the residual heat in certain operating and malfunction conditions. A steam generator (D1) has a connection, located on the live-steam and feed-water side, to the secondary circuit side of a safety condenser (SK1). The tertiary circuit side of the safety condenser is fed from a water reservoir (B) located at a physically higher level. The steam generated is vented to the atmosphere through a blow-off line (b2) which may include a separator. A make-up feed device (E1) is connected to the secondary side of the steam generator. Because of the higher location of the safety condenser with respect to the steam generator, the heat energy in the secondary cooling circuit circulates by natural circulation.

Abstract: Method of cooling a fuel assembly-transport container with a cooling circuit which includes the interior of the transport container and is traversible by a vaporizable coolant such as water, which includes feeding the coolant to the transport container at the start of the cooling operation at so low a rate that a vapor thereof is formed, withdrawing the vapor from the transport container, and maintaining the cooling through heat-removal by the withdrawn vapor until a reduction in the temperature of the withdrawn vapor occurs, and cooling circuit for performing the foregoing method.