Abstract: A nuclear power plant provides for delivery of nanoparticles to coolant found in the containment, for example during severe accident scenarios. The nanoparticles advantageously can be delivered passively or actively independently of any emergency core cooling system. The nanoparticle supply can include for example tanks storing nanofluids or solid nanoparticles, or dissolvable paints containing nanoparticles. Methods for providing the nanoparticles are also provided.

Abstract: A transport or storage cask comprises a cask body, a modular thermal conducting and shielding system and a mechanical attachment. The modular thermal conducting and shielding system includes a modular fin and a modular neutron shield. The mechanical attachment retains the modular thermal conducting and shielding system to the cask body. The modular fin is disposed between the modular neutron shield and the cask body. The modular fin is capable of dissipating thermal energy from the cask body.

Abstract: An integrated head assembly (100) is disclosed for a nuclear reactor. The preferred integrated head assembly includes a lift assembly (150) that supports the reactor vessel closure head (90) and integrated head assembly for removal, a separate support structure (202) supported by a ring beam (151) that sets atop the reactor vessel closure head, a shroud assembly (200), a seismic support system (300), a baffle assembly (500), a missile shield (400), and a CRDM cooling system. The CRDM cooling system draws cooling air into the baffle assembly, downwardly past the CRDMs (96), outwardly to upright air ducts (600), upwardly to an upper plenum (680), and out of the assembly through the air fans (190). In a second embodiment the integrated head assembly (1100) includes a missile shield (1400) and CRDM cooling system (1600) that permits access to individual CRDMs from above.

Abstract: The invention is a door actuator and alignment apparatus for opening and closing the 15,000-pound horizontally sliding door of a storage overpack. The door actuator includes a ball screw mounted horizontally on a rigid frame including a pair of door panel support rails. An electrically powered ball nut moves along the ball screw. The ball nut rotating device is attached to a carriage. The carriage attachment to the sliding door is horizontally pivoting. Additional alignment features include precision cam followers attached to the rails and rail guides attached to the carriage.

Abstract: Control device for a cooling circuit which enables a pressure tank of a reactor to be cooled even when a serious failure occurs, without having to resort to the use of external energy. One or more rods is disposed below a bottom cap of the reactor pressure tank. Each rod is connected to an emergency cooling system by a transmission system. The end of each rod opposite the transmission system is arranged at a distance of approximately 3 cm from the bottom cap. A hydraulic system is used advantageously as a transmission system. Each rod is placed vertically on a hydraulic cylinder arranged in a parallel position with respect to the axis of the reactor pressure tank, and each cylinder is connected to the emergency cooling system. When several hydraulic cylinders are used, they are connected to each other by hydraulic lines.

Abstract: The present invention provides a boiling water reactor nuclear power plant in which a reactor core support plate, upper grid plate, and a reactor core consisting of fuel assemblies supported by these plates are provided in the inner base portion of a nuclear reactor pressure vessel. Control rod guide tubes and a reactor core shroud are positioned over the upper grid plate, and a control rod drive mechanism is provided further above same, whereby the control rods can be inserted from above the reactor core, and natural circulation of cooling water inside the reactor can be achieved by means of a chimney effect of the control rod guide tubes. According to the above structure, there can be provided a compact and economical nuclear power plant.

Abstract: Passive emergency cooling in response to a loss of coolant accident (LOCA) in a PWR, having an integral reactor pressure vessel incorporating the steam generators and housed in a small high pressure containment vessel, is provided by circulating cooling water through the steam generators and heat exchangers in an external tank to cool the reactor vessel at a rate sufficient to lower the pressure in the reactor vessel below that in containment to reverse mass flow out of the reactor vessel and keep the reactor core covered without the addition of makeup water. Suppression tanks inside the small high pressure containment structure limit peak blowdown pressure in containment and provide flood-up water and gravity fed makeup water to cool the core. Diverse cooling is provided by natural circulation of air, and if needed, water, over the spherical containment structure.

Abstract: A reactor containment vessel of a boiling water reactor configured to contain a reactor pressure vessel. The reactor pressure vessel is connected to at least one main steam pipe which penetrates the reactor containment vessel at a main-steam-line penetration point. The main-steam-line penetration point is disposed on a first side of the reactor containment vessel. Distance between outer surface of the reactor pressure vessel and inner surface of the reactor containment vessel on the first side is longer than the distance on a second side which is opposite to the first side.

Abstract: The present invention, in one form, is a natural circulation reactor having, in one embodiment, a layer of high aluminate cement concrete disposed between an uninsulated steel liner and a prestressed concrete reactor vessel. The prestressed concrete reactor vessel includes a concrete shell having a cavity therein. The steel liner is positioned in the cavity and spaced from the concrete shell so that an insulating chamber is formed between the steel liner and the concrete shell. The insulating chamber is filled with high aluminate cement concrete which is configured to substantially insulate the concrete shell from the steel liner and to transfer loads such as pressure from the liner to the concrete shell.

Abstract: A shield building peripherally surrounds a containment vessel 3 and has an outer wall 9 with air inlets 4 adjacent to an upper end of the outer wall, a roof 10 contiguous with the upper end of the outer wall 9 having a central opening 12 and an inner wall 11 extending downward from a lower surface of the roof 10 adjacent to a peripheral edge of the roof and facing via gaps 13 and 14 to inner and outer peripheries of the outer wall 9 and containment vessel 3, respectively. The outer and inner walls 9 and 11 and the roof 10 are integrally provided by a steel structure to attain simplification in structure and reduction in quantity of the shield building.

Abstract: A head assembly of a reactor pressure vessel in an ice condenser plant is retrofitted to permit the assembly to be removed during a later refueling operation in reduced time and with reduced exposure to radiation by operating personnel. The portions of the ductwork ventilation system that originally provided cooling air to CRDMs are removed below the seismic support platform. The original CRDM cooling shroud that surrounds the lower portion of the CRDM assemblies is extended to the seismic support platform. A plenum is mounted on the seismic support platform and in air flow communication with interior portion of the extended CRDM cooling shroud. The plenum fits under the missile shield. Spool pieces are connected between the plenum and the portion of the ductwork adjacent to the seismic support platform.

Abstract: A nuclear steam supply containment system employing prefabricated component supports that are surrounded by steel concrete forms and anchored to the floor liner of a nuclear containment. The prefabricated component supports extend through the concrete forms and a reinforce concrete slab cap to a support elevation for the component. A second inner steel concrete form can be employed to form an annular concrete channel through which the supports extend. The center of the inner form can be filled with a sand-like substance, radiation absorber material or concrete grout.

Abstract: A reinforced concrete containment vessel in a nuclear reactor includes a cylindrical shell having a side wall. The side wall includes an opening and a plurality of reinforcing bars, at least one of which is interrupted at the side wall opening. A reinforcing plate having an opening is located in the cylindrical shell so that the reinforcing plate opening is aligned with the side wall opening and the interrupted reinforcing bars are connected to the reinforcing plate. Reinforcing bar terminators connect the reinforcing bars to the reinforcing plate.

Abstract: A liquid metal nuclear reactor is described. The reactor includes a concrete reactor silo, and at least one primary vessel located in the reactor silo and coupled to a reactor shield deck. Each primary vessel is substantially surrounded by a containment vessel in a spaced apart relationship. The reactor also includes a heat removal system which includes a guard vessel substantially surrounding each containment vessel in a spaced apart relationship, at least one inlet conduit in fluid communication with the ambient atmosphere outside the nuclear reactor, and at least one outlet conduit in fluid communication with the ambient atmosphere outside the nuclear reactor. A fluid flow heat transferring flowpath is formed by the inlet conduits, the space intermediate the guard vessel of each primary vessel and the containment vessel of each primary vessel and the outlet conduits.

Abstract: One of methods for carrying out a reactor vessel according to the present invention comprises the steps of removing an overhead traveling crane in a reactor containment vessel of a pressurized water reactor, or the steps of, in an area where an overhead traveling crane is installed, operating the overhead traveling crane to move aside for creating a space, through which the reactor vessel is able to pass, and then carrying out the reactor vessel through an opening provided in a top portion of the reactor containment vessel. With the present method, the reactor vessel of the pressurized water reactor can be carried out in a short time with high efficiency.

Abstract: A forged nozzle shell course for a pressure vessel includes shell course comprising at least one reinforcement portion extending radially outward from an outer surface of the shell course with each reinforcing portion including a nozzle having a radius. The nozzle includes a bore extending from an outside surface of the reinforcing portion to an inside surface of the shell course, and at least one extension attachment surface located adjacent to and coaxial to the bore. The reinforcing portion having a longitudinal dimension equal to about 2.0 times the radius of the nozzle, and a circumferential dimension equal to about 1.5 times the radius of the nozzle, measured from the centerline of the nozzle bore.

Abstract: A forged upper shroud section which may be machined from a single piece rectangular cross-section ring forging and includes a circular flange and a cylindrical shell is described. Openings and slots are machined into the flange to align and support the shroud head. A groove is machined along an inside surface of the cylinder section, and the groove may be used to support top guide grid (not shown). An end of the cylinder section is machined with a weld prep for attachment to the core section of the shroud.

Abstract: A nuclear power plant includes at least two reactor vessels enclosed within a single containment building. In a first embodiment, the reactor vessels and steam generators operate separately from one another. In a second embodiment the reactor vessels jointly provide heat to a common header having a plurality of steam generators associated therewith. In a third embodiment, the reactor vessels are completely integrated with one another by means of a single control and coolant system.

Abstract: Passive aerosol retention apparatus positioned in the connecting vents of a nuclear reactor containment are described. The aerosol retention apparatus minimizes aerosol transport from the lower drywell to the upper drywell of the reactor containment. The retention apparatus includes a substantially cylindrical housing and a flow modulator positioned inside the housing and extending at least partially from a first end to a second end of the housing. The flow modulator includes a helically shaped baffle positioned in the housing so as to be coaxial with the housing. The baffle is coupled at each end to the housing by attachment bars.

Abstract: Modified passive containment cooling systems for cooling a reactor core of a boiling water nuclear reactor are described. The reactor core is positioned in a reactor pressure vessel which is located in a drywell of the nuclear reactor. The passive containment cooling system (PCCS), in one form, includes an IC/PCC pool, a GDCS pool, a suppression pool, and a condensate drain tank. The IC/PCC and the GDCS pool each are substantially isolated from the drywell, and the suppression pool is separated from the drywell by a wall having a spill-over hole therein. An equalizing line extends between the suppression pool and the RPV and is configured to transport water from the suppression pool to the RPV. The condensate drain tank is positioned in the drywell and includes a base wall having a sidewall extending therefrom to define a fluid retaining cavity. A steam inlet line extends from within the drywall to a set of passive containment cooling condensers, which condense steam generated within the drywall to water.

Abstract: A seismically isolated liquid metal reactor power block is described. In one embodiment, the liquid metal reactor power block is a substantially rectangular nuclear plant with two nuclear islands and a common liquid metal service facility commonly supported on a seismic isolation platform near grade level. The seismic isolation platform supports the nuclear islands in a mirror-symmetric arrangement on opposite sides of a shared liquid metal service facility. A containment pressure suppression system connects the primary pressure relief volumes of the containment structures of each nuclear island to that of the other and also to a common pressure relief volume in the liquid metal service facility, thereby reducing the pressure load on each individual containment structure.

Abstract: A primary containment vessel comprises an outer peripheral concrete wall surrounding a reactor pressure vessel, a pipe arrangement of a reactor water recirculation system and other reactor systems and equipments, a mat concrete wall positioned below the outer peripheral concrete wall, a reactor pressure vessel (RPV) pedestal supporting the reactor pressure vessel, a horizontal wall joining the outer peripheral concrete wall and the RPV pedestal, upper and lower dry wells, a wet well having a suppression pool in which water is stored, an isolation member for air-tightly isolating the upper dry well and the lower dry well at a position supporting the reactor pressure vessel, vent pipe arrangement used for the upper dry well communicating the upper dry well with the suppression pool, a high pressure gas inflow member used for the upper dry well located in a communicating hole formed to the RPV pedestal so as to communicate the vent pipe used for the upper dry well with a gas phase section of the wet well, anothe

Abstract: A seismic load suppressing system for a nuclear reactor that reduces the seismic input to the reactor and the internal components of the reactor including the fuel is described. The seismic load suppressing system includes, in one embodiment, a plurality of seismic isolators positioned circumferentially between the reactor pedestal and a lower pedestal and a plurality of displacement limiters coupled to a lower pedestal skirt and positioned adjacent the reactor pedestal. The seismic isolators include a plurality of alternating layers of a resilient material and steel plates bonded together. Each displacement limiter includes a cantilever beam. The beam includes a beam core and two steel plates laminated on opposing outer surfaces of the beam core. The steel plates are fabricated from carbon steel having a lower yield strength than the beam core.

Abstract: Support assemblies for allowing RPV radial expansion while simultaneously limiting horizontal, vertical, and azimuthal movement of the RPV within a nuclear reactor are described. In one embodiment, the support assembly includes a support block and a guide block. The support block includes a first portion and a second portion, and the first portion is rigidly coupled to the RPV adjacent the first portion. The guide block is rigidly coupled to a reactor pressure vessel support structure and includes a channel sized to receive the second portion of the support block. The second portion of the support block is positioned in the guide block channel to movably couple the guide block to the support block.

Abstract: Breaker valve assemblies for a simplified boiling water nuclear reactor are described. The breaker valve assembly, in one form, includes a valve body and a breaker valve. The valve body includes an interior chamber, and an inlet passage extends from the chamber and through an inlet opening to facilitate transporting particles from outside of the valve body to the interior chamber. The breaker valve is positioned in the chamber and is configured to substantially seal the inlet opening. Particularly, the breaker valve includes a disk which is sized to cover the inlet opening. The disk is movably coupled to the valve body and is configured to move substantially concentrically with respect to the valve opening between a first position, where the disk completely covers the inlet opening, and a second position, where the disk does not completely cover the inlet opening.

Abstract: In order to support a shroud against bending, shear, stress and torsion, straps which are preferably formed of the same material as the shroud, are placed in strategic positions with respect to cracks or the like type of weaknesses which have been detected, and fastened in place using a suitable fastening technique. In the preferred embodiments of the invention holes are formed using an EDM technique and bolt units which have an expanding portion are inserted into the holes, torqued and expanded in a manner which fastens the strap to the shroud. Welding and the like type of fastening techniques are not excluded and may used alternatively or in combination with the bolting technique as required.

Abstract: In a method of construction of a reinforced concrete diaphragm floor of a nuclear reactor reinforced concrete containment vessel, a bottom surface of the diaphragm floor is provided in the form of an iron plate. The iron plate, an iron bar beam portion for supporting the load provided by concrete during a concrete pouring time, and a reinforcing bar member to be buried in the concrete of the diaphragm floor are assembled outside of a building in which the nuclear reactor is to be embodied. The above members are carried using lifting machinery and are set in a permanent receiving member which is provided on both a main body of the nuclear reactor pressure vessel and a steel member serving as a concrete mold frame of an outer wall of the nuclear reactor reinforced concrete vessel. A concrete pouring is carried out in stages so as to form successive layers of concrete during plural pouring times.

Abstract: A vertical seismic isolation structure is capable of achieving vertical seismic isolation of nuclear reactor components connected to each other by primary pipings, while suppressing the relative displacement with respect to the primary pipings. A nuclear reactor vessel, circulating pumps and heat exchangers, all of which are connected to each other by primary pipings in which a coolant is circulated, are mounted on a common deck. Vertical seismic isolators each of which has laminated large coned disc springs and is capable of expanding and contracting in only the vertical direction are installed on the top of a concrete wall surrounding the respective nuclear reactor components. The common deck is placed on all the vertical seismic isolators so as to support the entire seismic isolation structure (the common deck, the nuclear reactor components, etc.).

Abstract: A circular outage cover of light-weight composite material is normally situated in a standby position adjacent to the opening at the outer end of the equipment access tunnel of a nuclear reactor containment vessel. In case of an emergency during an outage, the outage cover can be quickly rolled into position and engaged with a transition ring provided as an extension of the tunnel by retractable retaining shoes on the retaining ring and an inflatable seal carried by the outage cover. The ability of the outage cover to be closed quickly makes it possible to keep the operational cover open throughout most of the outage, and reduces the overall outage time. Hydraulic, pneumatic and electrical services pass radially through the transition ring and do not interfere with closure of the outage cover. An auxiliary diaphragm cooperable with the transition ring is used for pressure testing of the outage cover.

Abstract: A pressure suppressing and aerosol scrubbing system configured to be located between low pressure upper containments associated with modular reactor vessels is described. In one embodiment, the pressure suppression and scrubbing system includes a water tank having connected, partially filled water chambers and a vertical baffle having horizontal vent holes positioned near the bottom of the tank. Each water chamber is connected by a vent/relief line to one of the respective rectangular upper containments. The partially filled water tank assures that the respective containments are isolated from each other under normal operating conditions due to the water trap inherent in the system. In the event that an accident occurs in one of the reactors, the affected containment is heated by the sodium spray and/or pool fire and such heat forces its way through the pressure suppressing and scrubbing system to the unaffected reactor containment.

Abstract: A nuclear reactor plant has a nuclear reactor vessel in a containment vessel. Air ducts, sump discharge lines, service water lines and other non-process non-critical lines extending through the wall of the containment vessel can be isolated passively (i.e., without instrumentation and control systems or power) should a postulated event which raises the atmospheric temperature within the containment vessel occur. The passive containment isolation system includes an isolation valve disposed in the non-process line and an actuator responsive to the atmospheric temperature within the containment vessel. The actuator is operatively connected with the isolation valve for closing the non-process line in response to the atmospheric temperature. The actuator is preferably disposed in or adjacent a containment sump at the bottom of the reactor vessel or adjacent the reactor vessel cavity where the temperature of the local atmosphere will most rapidly rise.

Abstract: A wall, particularly a wall of a containment for a nuclear plant, a pool or a cavern, includes a bearing wall. A sealing element is disposed on at least one surface of the bearing wall and covers the bearing wall. A protective wall covers the sealing element. The protective wall is frictionally connected to the bearing wall. The protective wall may be formed of a plurality of parts. The frictional connection may be made by anchors as well as by prestressing or by adhesive bonding.

Abstract: A nuclear reactor having a pressure vessel which is open at the top. The open top of the pressure vessel is closed by a steel dome. A containment, which is open at the top, extends upward from and is joined to the top of the pressure vessel and has an open containment head at the top thereof. The open top of the containment is closed by a steel dome, thereby forming a containment well bounded laterally by the containment, on the bottom by the vessel closure and on the top by the containment closure. The pressure vessel can be a steel-lined prestressed concrete vessel, while the containment is formed by an extension of the prestressed concrete vessel. Alternatively, the pressure vessel and the containment are parts of a unitary steel vessel. Isolation valves are installed on each penetration pipeline to isolate the system in the event of a loss-of-coolant accident.

Abstract: A device for passively inerting the gas mixture forming in the reactor containment of a nuclear power plant in an accident situation is proposed, which device is based on the use of chemical substances which react or disintegrate, releasing an inerting gas or gas mixture when a certain temperature of reaction is reached. This device is especially suitable for use in connection with catalytic recombiners for removing hydrogen through oxidation with the oxygen present. The heat resulting from this exothermic process of recombination can be put to use for heating up chemical substances to the required temperature, these having temperatures of reaction that lie above the temperature (approximately 100.degree. C.) that develops in the reactor containment in an accident situation.

Abstract: In order to eliminate the need to weld, drill or otherwise machine a shroud structure which is used to surround a plurality of fuel assemblies in a nuclear reactor, a plurality of upper hanger rods interconnect a structure above the shroud to a support ring which is clamped about the upper periphery of the shroud. Lower hanger rods interconnect a lower edge or shoulder portion of the shroud with the support ring. Thus, through the upper and lower hanger rods and the support ring, the shroud can be supported within the RPV. The upper support ring is arranged to clamp the lower ends of the upper hanger rods against the upper outer peripheral portion of the shroud while the lower ends of the lower hanger rods are clamped against the lower peripheral wall portion of the shroud by a lower support ring.

Abstract: A passive and inherent shutdown heat removal method with a backup air flow path which allows decay heat removal following a postulated double vessel leak event in a liquid metal-cooled nuclear reactor. The improved reactor design incorporates the following features: (1) isolation capability of the reactor cavity environment in the event that simultaneous leaks develop in both the reactor and containment vessels; (2) a reactor silo liner tank which insulates the concrete silo from the leaked sodium, thereby preserving the silo's structural integrity; and (3) a second, independent air cooling flow path via tubes submerged in the leaked sodium which will maintain shutdown heat removal after the normal flow path has been isolated.

Abstract: The Pressurized Water Reactor (PWR) plant steam generators, which are normally located inside the primary containment, are located outside, in separate structures. This arrangement provides for the removal or repair of the individual "leaky" steam generators, while the others remain operational. It also significantly reduces the size and thereby the cost of the containment.

Abstract: A system of extracting fluid samples, either liquid or gas, from the interior of a nuclear reactor containment utilizes a jet pump. To extract the sample fluid, a nonradioactive motive fluid is forced through the inlet and discharge ports of a jet pump located outside the containment, creating a suction that draws the sample fluid from the containment through a sample conduit connected to the pump suction port. The mixture of motive fluid and sample fluid is discharged through a return conduit to the interior of the containment. The jet pump and means for removing a portion of the sample fluid from the sample conduit can be located in a shielded sample grab station located next to the containment. A non-nuclear grade active pump can be located outside the grab sampling station and the containment to pump the nonradioactive motive fluid through the jet pump.

Abstract: A passive cooling system for cooling an enclosure only when the enclosure temperature exceeds a maximum standby temperature comprises a passive heat transfer loop containing heat transfer fluid having a particular thermodynamic critical point temperature just above the maximum standby temperature. An upper portion of the heat transfer loop is insulated to prevent two phase operation below the maximum standby temperature.

Abstract: A method of constructing the top slab of a nuclear reactor container in which a flange for mounting the top head of the container is prepared separately from the sleeve of the container. When the outside diameter of the flange is greater than the inside diameter of a doughnut-shaped steel; reinforcement structure assembled on the container, the steel reinforcement structure is situated in place and then the flange is welded to the sleeve, thus shortening the construction period. Disclosed also is a nuclear reactor container constructed by this method.

Abstract: A boiling-water reactor plant employs a baffle that parallels the interior surface of a thermally-conductive containment wall, defining an intermediate condensate channel. When the plant turbine becomes isolated from the boiling-water reactor, the reactor is shut down and steam is released from the reactor pressure vessel to the containment. Steam rises through an opening at the top of the baffle, allowing some of the steam to condense on the interior surface of the containment. Condensate then flows into the channel, which is dimensioned so that noncondensable gases are dragged into the channel along with the condensate. This minimizes thermal insulation due to the noncondensables and enhances the transfer of heat from the containment. Furthermore, the noncondensable gases are dragged at a sufficient velocity to induce turbulence. The resulting mixing of condensate flow layers further improves heat transfer to the containment wall.

Abstract: A containment structure (1) for storage of nuclear fuel or liquids which have been in contact with nuclear fuel includes a concrete wall (3) and a concrete floor (2) with a corrosion resistant liner (5) fixed to and in contact with the walls and floor except at the junctions of the walls and floor at which the liner is curved to provide "soft corners" (7) to permit movement of the liner relative to the concrete walls and floor.The term "soft corner" as used in the context of the present specification denotes a region providing a gap or empty space or collapsible or compressible material, eg foam, between the stainless steel liner and the concrete walls and floor. Any collapsible or compressible material employed needs to be stable to the radioactive environment and for this reason it is preferred that a gap or empty space is employed.

Abstract: A reactor containment facility having a reactor pressure vessel containing a core; a dry well in which the reactor pressure vessel is arranged; a suppression chamber holding suppression-pool water and forming above the suppression-pool water a wet well; and a plurality of vent pipes allowing the dry well to communicate with the suppression-pool water; a steel wall which is in contact with the suppression-pool water of the suppression chamber and which surrounds at least the pool water so as to form a containment vessel which houses the dry well and the suppression chamber; and an outer peripheral pool containing cooling water in contact with the outer peripheral surface of the steel wall.

Abstract: In a liquid-metal cooled nuclear reactor using liquid metal as a coolant and having vessels and pipings for accommodating the liquid metal coolant, at least pat of the region surrounding a coolant pressure boundary defined at outer wall surfaces of the vessels and piping is occupied by a mass of a solidified liquid metal. The solid mass (e.g. sodium) actually forms the coolant pressure boundary so that it is not so necessary to ensure the soundness of the steel walls of the vessels and pipings which accommodate the liquid metal coolant.

Abstract: There is disclosed a nuclear reactor installation. An accumulator-type emergency core cooling system, a gravity-driven core cooling system and an equalizing system for submerging a reactor core are provided within a primary containment vessel containing a reactor pressure vessel in which the reactor core is disposed. These cooling systems are automatically operated sequentially in accordance with the pressure in the reactor pressure vessel without the need for any particular powered source. The primary containment vessel is made of steel, and the interior of this containment vessel is divided into a space containing the reactor pressure vessel and a space containing an operation floor in such a manner that the two spaces are isolated from each other.

Abstract: A water storage tank in the coolant water loop of a nuclear reactor contains a tubular heat exchanger. The heat exchanger has tubesheets mounted to the tank connections so that the tubesheets and tubes may be readily inspected and repaired. Preferably, the tubes extend from the tubesheets on a square pitch and then on a rectangular pitch therebetween. Also, the heat exchanger is supported by a frame so that the tank wall is not required to support all of its weight.

Abstract: A reactor building assembly includes a pressure vessel within a containment vessel surrounded in turn by first and second enclosures defining respective first and second chambers. A method of operation includes channeling fresh air downwardly by gravity through the second chamber and then channeling the fresh air laterally through the first enclosure adjacent to the bottom thereof and into the first chamber. The air is then channeled upwardly by natural buoyancy through the first chamber for cooling the first chamber and mixing with stale air therein. The stale air is then discharged from the first chamber upwardly through the top of the first enclosure to the environs.

Abstract: A pressure control chamber of a reactor containment vessel for receiving the atmosphere of the reactor containment vessel containing leakage steam developing in the event of an accident includes a pressure control pool, and a wet well disposed above the pressure control pool. The wet well is divided into an inner peripheral portion and an outer peripheral portion. The inner and outer peripheral portions are communicated with each other via the pressure control pool. An outlet port for flowing the atmosphere of the reactor containment vessel containing the leakage steam is provided at the inner peripheral side of the pressure control pool. When the atmosphere of the reactor containment vessel containing the leakage steam is introduced into the pressure control pool in the event of the accident, this atmosphere is condensed by the water in the pressure control pool, and the gas of this atmosphere not condensed is accumulated in the inner peripheral portion of the wet well.

Abstract: A reactor pressure vessel is disposed in a reactor containment vessel and is supported by a pedestal having a cylindrical structure. The inside of the reactor containment vessel is divided into upper and lower drywells by means of a diaphragm floor. A line, a cable and a duct are disposed in and between the upper and lower drywells in the reactor containment vessel. The pedestal comprising a plurality of concrete wall sections and a plurality of connecting vent sections which are arranged alternately along a circumferential direction of the cylindrical pedestal, wherein the line, the cable and the duct are arranged in each of the connecting vent sections and a vent pipe is arranged in each of the concrete sections. A vacuum breaker is further disposed in the reactor containment vessel at a portion above the open end of the vent pipe, the vacuum breaker is connected to a fixing pipe for mounting a vacuum breaker to the pedestal and the fixing pipe has one end opened to the drywell.

Abstract: The movable air baffle shield means in accordance with the present invention provides an efficient method of cooling the space surrounding the containment vessel while also providing the capability of being moved away from the containment vessel during inspection. The containment apparatus comprises a generally cylindrical sealed containment vessel for containing at least a portion of a nuclear power generation plant, a disparate shield building surrounding and housing the containment vessel therein and spaced outwardly thereof so as to form an air annulus in the space between the shield building and the containment vessel, a shield baffle means positioned in the air annulus around at least a portion of the sides of the containment vessel providing a coolant path between the baffle means and the containment vessel to permit cooling of the containment vessel by air, the shield baffle means being movable to afford access to the containment vessel.