Abstract: A device for collecting and cooling reactor-meltdown products from a reactor pressure vessel includes an antechamber disposed below the reactor pressure vessel and an expansion chamber for the reactor-meltdown products. A channel which is disposed between the antechamber and the expansion chamber has a partition being destructible by the reactor-meltdown products. A closure element which connects a coolant reservoir to the expansion chamber is destructible by the reactor-meltdown products. A method for collecting and cooling reactor-meltdown products from a reactor pressure vessel includes collecting reactor-meltdown products in an antechamber disposed below the reactor pressure vessel and keeping them in the antechamber for a predetermined time interval. A partition disposed between the antechamber and an expansion chamber is destroyed with the reactor-meltdown products. The reactor-meltdown products penetrate from the antechamber into the expansion chamber and are spread in the expansion chamber.

Abstract: A nuclear reactor has a core and a pressure vessel with a wall and an interior. A pressure relief responding as a function of temperature is provided in the case of insufficient core cooling (due to a highly improbable failure of the cooling devices and emergency cooling devices). A safety device protecting against overpressure failure of the pressure vessel upon insufficient cooling of the core includes a pressure pipe passing pressure-tightly through the wall and extending into the interior of the pressure vessel. The pressure pipe has at least one pressure compensation opening formed therein in the interior of the pressure vessel and has a fusible sealing body sealing the pressure compensation opening. The fusible sealing body is formed of a melting solder melting at a limit temperature, such as 600.degree. to 700.degree. C., and unblocking the pressure compensation opening, but keeping the pressure compensation opening sealed during normal operation.

Abstract: A nuclear reactor has a pressure vessel with an interior, a coolant conducting surface, such as a wall of the pressure vessel or a line passing through the wall of the pressure vessel, a pressure relief line, and a core. A safety device which protects the pressure vessel against overpressure failure upon inadequate cooling of the core includes a pressure relief valve being pressure-tightly inserted into the coolant conducting surface and having a seat, a closure element normally disposed on the seat for blocking a flow from the interior of the pressure vessel to the pressure relief line, an abutment, and a valve closing spring holding the closure element and being supported against the abutment. A force transmission element holds the abutment and has an end facing away from the abutment. A detent is disposed in the pressure vessel and fixes the end of the force transmission element. The detent is releasable in dependence on a given threshold temperature, for example 700.degree. C.

Abstract: A pressurized-water reactor installation comprises a pressure vessel containing a core, a main reactor coolant system formed by one or more main coolant loops which are each formed by a steam generator and a main coolant pump and main coolant piping interconnecting the vessel, pump and generator. A pressurizer is connected with the coolant system to maintain a normal operating pressure on water in the loop and which prevents the water from boiling in the loop and pressure vessel. An emergency core cooling system is provided which includes a supply of emergency water and activating means responsive to a drop in the normal operating pressure in the loop, for automatically feeding the emergency water into the vessel to flood the core. In case the pump fails to operate, the pressure in the loop increases due to overheating of the water.

Abstract: A bundle of individual measuring lines extends through the cover of a reactor pressure vessel, the bundle extending into a tubular mounting having a multiplicity of extending tubes through which the individual lines of the bundle extend. In each tube the line is passed through a sleeve slidably inserted in the tube and having an inner portion soldered to the line and an outer portion welded to the tube's outer end. The length of the sleeve and tube between the soldered and welded joints is made sufficient to prevent the heat of welding from effecting the soldered joints. Each line can be removed from its tube by cutting away the welded joint and removing the line with its sleeve from the tube. The line can be reinstalled by returning the sleeve to its tube and making a new welded joint with the sleeve spacing its soldered connection with the line far enough to prevent the welding heat from affecting the soldered joint between the sleeve and the line.