Abstract: An assembly includes a base grid configured to be disposed below a pressure vessel and spaced vertically above a floor of a containment vessel to define a sump therebetween. The assembly further includes an annular wall extending vertically upwards from the floor and laterally bounding the base grid and the sump. The wall separates the sump from a suppression pool, an inlet passage extending through the wall and providing flow communication between the sump and the suppression pool, and an outlet passage extending through the wall and providing flow communication between the sump and the suppression pool.

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 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 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 heat removal system for the under reactor pressure vessel area of a boiling water nuclear reactor system that provides both protection of the containment boundary from attack by molten core debris and cools the molten core debris to prevent a breach of the containment boundary in the unlikely event of a severe accident where the molten core penetrates the lower head of the reactor vessel is described. The heat removal system includes a glass matrix slab positioned adjacent the floor of the containment and a plurality of heat tubes at least partially embedded in the glass matrix slab and extending into the area under the nuclear reactor pressure vessel. The cooling system also includes a passive containment cooling system, and fused vent pipes connecting the suppression pool with the drywell.

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: A joint for interfacing a steel head closure and a steel-lined prestressed concrete reactor vessel (PCRV). The steel head closure is bolted to a thick steel annular plate and a thermal barrier is arranged in a volume bounded by the head ring, the liner and the concrete of the PCRV wall. The thermal barrier is made of zirconia sand or other material having a low thermal conductivity, a high bulk modulus equal to that of concrete, and a low shear modulus. Differential thermal expansion of the vessel head closure and PCRV is accommodated by a flexible connection of the PCRV liner to the inner periphery of the head ring. In the alternative, the steel head closure is interfaced to the top of the PCRV via a sliding joint or a thermal stress relief ring. In accordance with a further alternative, thermal stresses in the steel vessel head closure are mitigated by reducing the temperature of the head closure by installing thermal insulation on all internal surfaces thereof.

Abstract: A nuclear reactor including a heat pipe for transferring heat from the reactor pressure vessel to a steam supply vessel is described. More particularly, in one embodiment, the heat pipe includes an evaporator section positioned in the reactor vessel, a condenser section positioned in the steam supply vessel, and an adiabatic section extending between and in flow communication with the evaporator section and the condenser section. The adiabatic section of the heat pipe includes a substantially cylindrical outer sleeve and a substantially cylindrical inner sleeve. An annulus region is formed between the inner and outer sleeves and the annulus region is in flow communication with the steam supply vessel. An insulating layer covers an inner wall of the outer sleeve. A substantially annular wick member is positioned adjacent an inner wall of the inner sleeve, and a steam path is defined by an inner face of the wick member.

Abstract: A nuclear power generation complex constructed on a stratum of rock overlain by soil deposits. All major structures in the power generation complex (i.e., reactor, turbine, radwaste and control buildings) are located on a common mat foundation that houses elastomeric bearings or seismic isolators. The foundation includes a concrete slab supported by a plurality of pedestals. Each of the pedestals is embedded in the rock. Preferably, each pedestal is a circular metal shell filled with underwater-type concrete, and the concrete slab is reinforced with steel bars. For example, a reactor building is supported by one set of seismic isolators mounted on the concrete slab, and a turbine building is supported by another set of seismic isolators mounted on the concrete slab. The isolators filter out a great deal of the seismic vibratory inputs. The common mat foundation eliminates differential movements between the buildings.

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 corium protection assembly includes a perforated base grid disposed below a pressure vessel containing a nuclear reactor core and spaced vertically above a containment vessel floor to define a sump therebetween. A plurality of layers of protective blocks are disposed on the grid for protecting the containment vessel floor from the corium.

Abstract: A reactor building for enclosing a nuclear reactor includes a containment vessel having a wetwell disposed therein. The wetwell includes inner and outer walls, a floor, and a roof defining a wetwell pool and a suppression chamber disposed thereabove. The wetwell and containment vessel define a drywell surrounding the reactor. A plurality of vents are disposed in the wetwell pool in flow communication with the drywell for channeling into the wetwell pool steam released in the drywell from the reactor during a LOCA for example, for condensing the steam. A shell is disposed inside the wetwell and extends into the wetwell pool to define a dry gap devoid of wetwell water and disposed in flow communication with the suppression chamber. In a preferred embodiment, the wetwell roof is in the form of a slab disposed on spaced apart support beams which define therebetween an auxiliary chamber.

Abstract: A nuclear reactor system pressure vessel comprises a steel inner liner part, an intermediate insulative layer part and an outer pre-stressed concrete part encasing these parts. Use of the pre-stressed construction allows for construction of pressure vessels of larger size than heretofore, and this coupled with utilization of squatter reactor cores allows natural convective circulation in the reactor vessel of the heated water pool in the higher capacity systems currently being introduced. The reactor pressure vessel because of its suitability allows enhanced natural steam separation in the vessel and eliminates need for use of centrifugal steam separators. The outer vessel part can be a cast single piece structure or it can be an integrated concrete segment assembled structure embodying pre-stressing tendons arranged in various orientations to effect pre-stressing.

Abstract: A gravity driven cooling system pool is disposed at an elevated location with respect to the locations of nuclear fuel rods in a pressure vessel. In the event of a loss of coolant in the pressure vessel, steam pressure is initially reduced by venting the steam into the containment or a closed suppression pool containing a quantity of water under a large air space. The suppression pool condenses sufficient steam to lower the steam pressure in the pressure vessel so that water can flow by gravity from gravity driven cooling system pool to flood the fuel rods in the pressure vessel. An isolation condenser is submerged in a large supply of water elevated with respect to pressure vessel. Steam is admitted to the isolation condenser, or heat exchanger, where it is cooled by boiling the water surrounding it. This steam is vented to the atmosphere. A depressurization valve vents steam fro the pressure vessel into the containment to aid pressure reduction, and thus to aid the gravity flow of coolant.

Abstract: A suppression chamber in a nuclear reactor containment includes a heat exchanger disposed in a gas space above water in the suppression chamber. A gravity-driven pool contains a supply of make-up water that is gravity fed to the heat exchanger through a conventional level-maintaining valve such as a float valve. A top header in the heat exchanger includes a free surface area for permitting separation of steam from water, thereby permitting venting of vapor only, while retaining the liquid coolant in the heat exchanger. A downcomer tube permits return of excess water to a lower location for further use in the heat exchanger. The heat exchanger is normally sealed, whereby internal surfaces in the heat exchanger require only a small amount of low-volatility corrosion inhibitors to prevent corrosion on internal surfaces thereof. Locating the heat exchanger in the gas space in the suppression chamber reduces the amount of corrosion on its external surfaces.

Abstract: A suppresion chamber in a nuclear reactor containment includes a heat exchanger disposed in a gas space above water in the suppression chamber. A gravity-driven pool contains a supply of make-up water that is gravity fed to the heat exchanger through a conventional level-maintaining valve such as a float valve. A top header in the heat exchanger includes a free surface area for permitting separation of steam from water, thereby permitting venting of vapor only, while retaining the liquid coolant in the heat exchanger. A downcomer tube permits return of excess water to a lower location for further use in the heat exchanger. The heat exchanger is normally sealed, whereby internal surfaces in the heat exchanger require only a small amount of low-volatility corrosion inhibitors to prevent corrosion on internal surfaces thereof. Locating the heat exchanger in the gas space in the suppression chamber reduces the amount of corrosion on its external surfaces.

Abstract: A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

Abstract: A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.