Abstract: A pressurized nuclear water reactor has a substantially cylindrical flow liner with a cylindrical wall section and bottom and an open top. A barrel forms a riser chamber that contains the core in the flow liner. A pressure vessel contains the cylindrical flow liner to form a second annular chamber therebetween that contains a supplementary liquid coolant, with insulation means to provide a major portion of the supplementary liquid coolant at a first temperature and a minor portion thereof at a second higher temperature. Upon depressurization in the vessel, fluid communication means enable injection of supplementary liquid coolant from the second annular chamber into the core upon flashing of a minor portion to vapor. A further pool of water outside the pressure vessel, and insulation on the wall, maintain the desired temperature in the supplementary liquid coolant supply. Injection or removal of borated solution, as a chemistry control solution, into or from the supplementary liquid coolant is provided.

Abstract: The overflow in the secondary of a steam generator of a nuclear-reactor plant, which occurs when one or more primary tubes conducting the coolant are ruptured, is controlled. The secondary of the steam generator, which contains the water that is converted to steam, is connected through valves to the pressurizer relief tank. The level of the liquid in the shell is monitored. An alarm is sounded when the level of the liquid in the generator reaches a predetermined height alerting the operator. When the level reaches a greater height, the valves are opened and the liquid in the shell is discharged into the pressurizer relief tank. The liquid in the tank is discharged into the containment sump when a disc is ruptured. The time taken after the rupture is 30 minutes as mandated by safety regulations. If, after the liquid in the shell reaches the level at which the valves are opened, the level drops to a height at which steam may be injected into the pressurizer relief tank, the valves are automatically closed.

Abstract: The present invention provides a passive safety device for dumping steam from the steam generator of a nuclear power reactor in case of emergencies. The device comprises a steam ejector immersed in a storage tank of coolant water, a conduit connecting the steam ejector to the steam line from the steam generator, a heat exchanger having its inlet connected to the outlet of the steam ejector and the outlet to the storage tank, and a coolant pool in which the heat exchanger is immersed. Optionally, the output from the steam ejector may be connected to the feedwater line to the steam generator as an emergency feedwater supply.

Abstract: Container, especially for radioactive substances such as radioactive liquids, with an inner container for receiving these substances and an outer container, in which the inner container and thermal insulation between the inner and outer container are located. The inner container is associated with a cooling tube within the outer container which tube contains a coolant that can be circulated. A heat discharge tube likewise containing the coolant that can be circulated is arranged at the outer container. The cooling tube and the heat discharge tube are in communication with each other via connecting lines at both tube ends.

Abstract: A passive depressurization system for use during cold shutdown of a pressurized water reactor receives saturated steam from the reactor's pressurizer, condenses the steam to water, and returns the water to a nozzle within the pressurizer in order to provide a cooling spray which condenses steam within the pressurizer. The depressurization system may include coiled tubing, which is connected to input and output ports of the depressurization system by redundant valves, or a condenser formed by a housing having air vents provided by vent elements through the housing.

Abstract: A nuclear reactor, particularly a light water reactor or a helium-cooled high-temperature reactor, is provided with a pressure relief system for relieving pressure resulting under fault conditions from coolant in the reactor pressure vessel and/or the protective vessel of the reactor, wherein the coolant is conducted from the vessel or vessels to a pressure relief station downstream thereof. At the pressure relief station the coolant is fed into a liquid reservoir 4 from which the coolant in gaseous or vapor form is fed sequentially through a washing cyclone 13 and a drying cyclone 25. Most of the radioactive fission products carried by the coolant will have been removed by the liquid reservoir 4 and the washing cyclone 13, and the coolant leaving the cyclone 25 may be safely discharged to atmosphere. Both the liquid reservoir 4 and the washing cyclone 13 are provided with cooling circuits 8 to 12 and 14 to 23 respectively for the liquids.

Abstract: A pressure release arrangement for a pressure container such as a safety containment of a nuclear reactor, wherein a pressure release pipe extends through the containment walls and is closed at its inner end and connected to a drawbar mounted with its other end to a distant point of the container wall. The release pipe has within the containment an area of reduced thickness providing for a design breaking point at which the pipe is caused to rupture when the container is stretched by overpressurization beyond a predetermined point thereby relieving the pressure.With this arrangement, pressure is safely relieved before uncontrolled explosion of the containment but only when absolutely necessary.

Abstract: A process and an installation for the securing against excessive pressure in a prestressed concrete pressure vessel of a gas cooled high temperature reactor and for the prevention of activity release into the environment. The process comprises three steps and in each step pressure reducing installations become effective upon the rise of pressure in the prestressed concrete pressure vessel over a predetermined value. In the first step the pressure vessel is relieved by means of the operational gas purification apparatus and a conveying blower into the storage vessels for the cooling gas. In case of a further rise in pressure, in a second step a discharge path equipped with a safety valve and a check valve is opened, which also relieves into the storage vessels while by-passing the gas purification installation.

Abstract: A support structure for supporting a pressurizer safety and relief valve system above a pressurizer vessel comprises a ring girder which surrounds the pressurizer vessel wall and is supported on pairs of lugs spaced about the pressurizer wall. The ring girder supports columns for the system at locations spaced from the lugs, and support means in the form of frames distribute the load on the lugs. The frames have upper and lower bars and outer vertical bars, with spaced inner vertical bars. Biasing means are provided to attach the frames to the lugs and distribute the forces, and a projection on the ring girder fits into a groove of a support bar on the upper bar of the frame.

Abstract: The invention relates to a device for protecting a container containing a pressurized fluid.The device comprises a protection valve and an isolating valve, connected in series and whose opening is controlled by ancillary means, which are sensitive to two pressure thresholds in the container for successively controlling the opening of the isolating valve and then that of the protection valve, when the pressure rises. The isolating valve replaces the protection valve in the case where the latter becomes locked in the open position.Application more particularly to the protection of primary circuits in a pressurized water nuclear reactor.

Abstract: An underwater discharge system for discharging an effluent overboard through an aperture in a wall of an at least partially submersed structure. The effluent is discharged through a conduit into a pressurized chamber which is open to and extends below the surface of the water in which the effluent is to be discharged. The pressure in the chamber is maintained to sustain the level of water in the chamber below that at which the conduit enters the chamber. A tubular catchment for transporting the effluent to a location remote from the structure is positioned to have one end within the chamber, above water level, open to the chamber's atmosphere, and sized and arranged to receive the conduit within its opening. Pressure within the chamber is maintained to keep the effluent from spilling over the one end of the catchment into the water in the chamber. The other end of the catchment communicates with a discharge basin which transports the effluent to the remote location.

Abstract: A fission product scrubbing system comprises a water tank in the containment building; a dividing wall extending into the water tank for separating it into first and second compartments; a collection plenum normally hermetically sealed from the containment space and the environment externally of the containment building and being at least in part formed by the dividing wall and the level of water stored in the second compartment and a communication passage in the dividing wall underneath the water level in the first and second compartments for maintaining communication between the water stored therein. There is further provided a standpipe which extends from the containment space into the second compartment and which has flow distribution holes situated in the second compartment below the water level and above the communication passage, whereby gases passing from the containment space into the standpipe travel upwardly from the distribution holes through the water into the collection plenum.

Abstract: In a method of inhibiting or avoiding intermixing of the atmosphere which exists in a closed nuclear reactor containment space with a gaseous substance present in the same space a change in density of the atmosphere is induced in either lower or upper area of the space such that a stable atmosphere stratified into superimposed layers is formed in that space due to the change in density.

Abstract: In a nuclear power plant, a reactor building and a building annex to this reactor building are constructed as a unitary reactor combination building in which a condensate storage tank is accommodated and the inner wall of the condensate storage tank is lined with stainless steel plates.

Abstract: A steam generator for transferring the heat carried by a liquid metal to a water - steam circuit. It comprises a drainage tank directly suspended at the lower end of the envelope. A drainage tube connected to the bottom of the envelope is disposed within the tank and carries a burster disk at its end. This disk is placed behind a detachable observation window, fixed to the drainage tank and permitting the replacement thereof.

Abstract: A control system for overpressure protection of the reactor coolant boundary (14) in a nuclear power plant, comprising a pressure relief line (18a) having a power operated relief valve (24a) controlled by a circuit responsive to the condition of the reactor coolant and a control logic. The circuit includes a mode selector switch (80) having a NORMAL position (82) for establishing a full power overpressure relief valve setpoint (62) and a LTOP position (84) for establishing a low temperature overpressure relief setpoint (58). The control system logic opens the relief valve (24a) when (a) the mode switch is in the NORMAL position and the coolant pressure exceeds the full power setpoint (62), or (b) when the mode switch is in the LTOP position, the coolant temperature is less than a preselected value (52) and the coolant pressure exceeds the LTOP setpoint (58).

Abstract: The present invention is related to nuclear reactors. More specifically, this invention is directed to a means for venting pressurized water reactors.

Abstract: The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

Abstract: A containment vessel for a nuclear reactor having a dry well for mounting therein a pressure vessel for containing the nuclear reactor, a pressure suppressing chamber having a pool of coolant therein, and a vent pipe device for releasing therethrough into the pool of coolant within the pressure suppressing chamber steam which will be produced as a result of the occurrence of an accident and escape into the dry well. The vent pipe device includes a plurality of vent pipe members inserted in the pool of coolant within the pressure suppressing chamber and each having at least one exhaust port opening in the coolant. The vent pipe members are divided into a plurality of groups in such a manner that the vent pipe members of different groups differ from one another in the length of submerged portions of the vent pipe members interposed between the liquid of the coolant within the pressure suppressing chamber and the exhaust ports of the vent pipe members.

Abstract: Device for safety injection on a pressurized-water nuclear reactor, including at least two separate injection trains each consisting of at least one set of means (60, 61, 62) for pumping water from a reservoir (58, 59) arranged outside the safety enclosure, and a main injection pipe (64, 65) connected to a distributor drum (70, 70') for the distribution of the water into each of the cold arms of the primary circuit. From each of the main pipes (64, 65) there is tapped off outside the enclosure an auxiliary pipe (84, 85) in which is located a block valve (96, 97). The auxiliary pipes (84, 85) include a branching-off (86, 87, 88, 89) for placing the auxiliary pipe (84, 85) into communication firstly with a cold arm (52, 53, 54, 55) and secondly with a hot arm (56, 56'). The invention is applicable in the event of leakage in the primary circuit of a pressurized-water nuclear reactor.

Abstract: A standpipe runs up from a liquid storage vessel located between the safety vessel of a nuclear reactor and the safety enclosure around it and connected by a pressure equalization line to the interior space of the safety vessel. Undesired pressure increases in the interior of the safety vessel are absorbed by pushing water out of the storage vessel up the standpipe to a discharge above the safety vessel which is still within the safety enclosure. With sufficient pressure, the liquid, which may be conveniently water, flows from the standpipe to an overflow collar at the top of the safety vessel from which it runs down over the surface of that vessel to cool it. Water that evaporates is collected on the interior wall of the safety enclosure and also percolates down to the base of the safety enclosure, from which it is pumped back to the overflow collar, from which it can flow back into the pressure vessel when the pressure inside the safety vessel of the reactor goes back to normal.

Abstract: It is desirable to being able to vary the temperature of a loop exposed to a flow of hot gases in gas cooled nuclear reactor installations without thereby affecting the gas temperature in the other loops. It should be possible in an extreme case to take the affected loop out of service. This is achieved by arranging under the heat absorbing components in the hot gas channel a means for mixing gas connected with a cold gas line.

Abstract: A pressure surge attenuation system for pipes having a fluted region opposite crushable metal foam. As adapted for nuclear reactor vessels and heads, crushable metal foam is disposed to attenuate pressure surges.

Abstract: Heat retarding closure system for partitions having pressure relief openings formed therein especially in nuclear reactor buildings where main coolant nozzles of a reactor pressure vessel penetrate a biological shield, including lightweight construction closure elements having a side facing the reactor and anchors for holding the closure elements, the closure elements being pushable out of the anchors by an overpressure in a given pressure difference direction on the reactor side, and an outer sealing blowout skin, the closure elements being in the form of heat-retarding cassette inserts having a front surface with a peripheral shearing edge formed thereon resting against the blowout skin, and the blowout skin having a given thickness in the given pressure difference direction enabling the cassette insert to shear off the blowout skin and be pushed out of the anchors when a given pressure difference is at least reached.

Abstract: The invention pertains to a containment system for a nuclear power plant which provides protection in the event of a loss of coolant accident or other malfunctions wherein the stored energy within the components of the system is contained and absorbed by the use of a plurality of coolant reservoirs capable of absorbing steam and supplying coolant to the reactor coolant system and feedwater to the secondary systems. The system includes a plurality of steam generators which may selectively be employed as an energy source during cooldown, and the design of the reservoirs provides high initial energy absorption as well as extended energy dissipation during cooldown.

Abstract: Malfunction under water-solid conditions responsive either to increase in mass flow or increase in heat flow into the reactor coolant is suppressed. The power-actuable reactor-coolant relief valve is opened for increase in reactor-coolant mass influx if the rate of change of coolant pressure exceeds a setpoint during a predetermined interval, if, during this interval, the coolant temperature is less than a setpoint and if the level of the fluid in the pressurizer is above a predetermined setpoint (water-solid state). The interval is set to preclude opening of the relief valve for transients.

Abstract: Process and device for emergency cooling of a nuclear reactor comprising a steam generator (2) heated by a primary circuit and cooled by a secondary circuit producing steam, and in which in case of an emergency shutdown of the reactor, the emergency feed (50) of the secondary circuit is provided from an emergency reservoir (5), by an auxiliary pump (51) driven by steam derived at the output from the generator. At least part of the steam continuing to be produced during the cooling process is condensed in an air condenser (6) and the condensed water is recycled to the emergency reservoir (5). The power for the air condenser is supplied from another withdrawn portion (70) of steam.

Abstract: In a steam condensing apparatus according to this invention, a plurality of branch pipes each having an exhaust nozzle are attached to the distal end of a guide pipe which extends into coolant to eject steam of coolant into the coolant, the branch pipes having different nozzle diameters and/or pipe lengths.

Abstract: In a blow-off device for limiting excess pressure in nuclear power plants, at least one condensation tube disposed so that a lower outlet end thereof is immersed in a volume of cooling water in a condensation chamber having a gas cushion located in a space above the volume of cooling water, and the upper inlet end of the condensation tube extending out of the volume of cooling water and being connectible to a source of condensing steam or a steam-air mixture, the outlet end of the condensation tube being provided with an insert for smoothing the condensation, said insert comprising wall portions forming storage chambers distributed over the length of said tube outlet end and having overflow edges for the cooling water, whereby a spraying action multiplying the heat-transfer surface between the cooling water and a flow of the steam is releasable at said overflow edges when cooling water received in said storage chambers is alternatingly depleted and replenished due to pressure and water-level fluctuations with

Abstract: A modularly constructable support arrangement is provided for pressurizer safety and relief valves in a nuclear power plant. A common header is supported by four sets of columnar legs which are secured to pressurizer vessel side wall lugs. The safety and relief valves are securely disposed and connected through short pipe runs to discharge steam into the header.

Abstract: Blowdown device for steam power plants includes a tube extending into a volume of water, the tube being formed with a multiplicity of holes having a substantially uniform diameter for introducing, into the water, steam that is flowing in the tube, the holes being disposed in rows spaced one from another a distance equal to at least 2.5 times the diameter of the holes.

Abstract: An improved pressurized fluid reactor system having a fluid cooled reactor core in which the coolant pump for delivering fluid to the reactor core is driven by a pump motor through a unidirectional drive means which enables the pump to operate at a greater speed than the pump motor in the pumping direction only. A preferred unidirectional drive means in the form of a ratchet means is disclosed.

Abstract: Apparatus for preventing the diversion of plutonium in nuclear fuel reprocessing plants. The apparatus includes various piping arrangements which prevent plutonium in a liquid state from being drawn out of a nuclear fuel reprocessing cell through conduits which are normally accessible to the operators of the facility.

Abstract: The nuclear boiler comprises at least one heat exchanger located externally of the reactor vessel in order to effect heat exchange between the liquid metal coolant in the form of liquid and water to be vaporized and superheated together with a main storage tank connected to the reactor vessel for receiving liquid metal and inert gas. A main storage tank pipe system fitted with valves consists of a first overflow pipe for connecting the top of the reactor vessel to the bottom of the storage tank, and at least one second pressure-equalizing pipe between the top of the reactor vessel and the top of the storage tank. Controlled-atmosphere compartments forming the reactor containment structure and containing the unclear steam supply systems provide biological protection for operating personnel and guard against impacts of external origin.

Abstract: The mechanical strainer unit is connected to a flanged conduit which originates in and extends out of a suppression chamber in a nuclear reactor. The strainer includes a plurality of centrally apertured plates positioned along a common central axis and in parallel and spaced relationship. The plates have a plurality of bores radially spaced about the central axis. Spacer means such as washers are positioned between adjacent plates to maintain the plates is spaced relationship and form communicating passages of a predetermined size to the central apertures. Connecting means such as bolts or studs extend through the aligned bores to maintain the unit in assembled relationship and secure the unit to the pipe. By employing perforated plates and blocking off certain of the communicating passages, a dual straining effect can be achieved.

Abstract: Boiling reactor comprising a reactor core (1) and a pressure vessel (2) enclosing said reactor core and being provided with at least one conduit for discharged steam and at least one conduit for feed water and during normal operation being filled with water up to a certain normal level (11), the steam pressure in the pressure vessel having a substantially constant value of at least 5 MPa. The pressure vessel (2) is surrounded by a water-filled pool (3) with a water volume above the reactor core (1) which is considerably greater than the water volume within the pressure vessel (2). The pressure vessel (2) is a concrete vessel having an internal thermal insulation (9). The reactor comprises emergency cooling pipes (19, 20) with valves (19', 20') connecting the reactor vessel (2) to the pool (3). The valves (19', 20') are normally closed. The pipes (19, 20) are positioned at different levels.

Abstract: The system according to the invention comprises a first room which accommodates a reactor plant and an active-type sprinkler means to condense steam released by the ebullient coolant after an accident. A loss of coolant may occur at any point of the reactor plant; that notwithstanding, the rising pressure in said first room drives the air out of that room through holes provided in the walls of the room in immediate proximity to the floor and spaced at a maximum distance from one another over the perimeter of the walls. The air is forced into an intermediate chamber wherefrom it is directed to a second room through channels and a basin-type condenser arranged in a second room. The length of the channels is selected so as to form a water seal to prevent the backflow of air driven from the first room to the second room and thus produce rarefaction in the first room.

Abstract: A device having a tubular body of an increased diameter closed at its bottom and connected at its top to the lower end of a vent pipe in such a state that the tubular body is immersed in a water pool. The tubular body is formed in its side wall with a multitude of openings for venting steam therethrough to the water pool to condense the same.

Abstract: Nuclear reactor installation having a concrete cell disposed beneath the earth of a hill for enclosing activity-carrying components includes at least one additional concrete cell disposed in the earth separated from the first-mentioned concrete cell, the additional concrete cell having at most one-fortieth the volume of the first-mentioned concrete cell and being at least predominantly of shell-like construction, and including equipment of use for the nuclear reactor installation received in the additional concrete cell.

Abstract: A secondary coolant circuit for a nuclear-reactor of the liquid-metal cooled type, said circuit comprising at least one intermediate exchanger mounted in the vessel of said reactor, outside said vessel a steam-generator for the exchange of calories between the secondary liquid-metal flowing through said secondary circuit and water-steam, at least one pump for circulating said secondary sodium and one tank for storing said secondary liquid-metal and recovering those products generated by a possible liquid-metal-water reaction in said steam-generator, said liquid-metal being likely to occupy the lowest possible level in said tank, said secondary coolant circuit being characterized in that said tank is situated at the lowest possible level in the nuclear installation, in that the lower extremity of the liquid-metal outlet duct of said steam-generator is directly dipped into said tank, in that, in said tank above the liquid-metal, is maintained an inert gas cover at such a pressure that it balances the liquid-met