Abstract: A process for producing a metal-molybdate material is provided. The process includes a step of reacting a metal molybdenum (Mo) material in a liquid medium with a first acid to provide a Mo composition and combining the Mo composition with a metal source to provide a metal-Mo composition. The metal-Mo composition can be pH adjusted with a base to precipitate a plurality of metal-Mo particulates.

Abstract: A packing device for filling fuel elements with a powder through a fill aperture in an outer shell of the fuel element, including a stationary base, a clamp assembly including a body defining a bore therein, the bore being configured to slidably receive a fuel element therein, wherein the clamp assembly is movable along a vertical axis with respect to the stationary base, a cam assembly including a cam and a drive motor configured to rotate the cam, wherein rotation of the cam alternatingly raises the clamp assembly up along the vertical axis and subsequently drops the clamping assembly, and a powder reservoir assembly including a powder reservoir and a fill needle in fluid communication with the powder reservoir.

Abstract: Plurality of layers form a nuclear fission reactor structure, each layer having an inner segment body, an intermediate segment body, and an outer segment body (each segment body separated by an interface). The layers include a plurality of cladding arms having involute curve shapes that spirally radiate outward from a radially inner end to a radially outer end. Chambers in the involute curve shaped cladding arm contain fuel compositions (and/or other materials such as moderators and poisons). The design of the involute curve shaped cladding arms and the composition of the materials conform to neutronic and thermal management requirements for the nuclear fission reactor and are of sufficiently common design and/or have sufficiently few variations as to reduce manufacturing complexity and manufacturing variability.

Abstract: A nuclear reactor having a pressure vessel, the reactor including a first plenum plate disposed within the pressure vessel, the first plenum plate defining a first plurality of apertures, a second plenum plate disposed within the pressure vessel, the second plenum plate being parallel to the first plenum plate and defining a first plurality of apertures, a fuel element including a fuel element flow tube extending through a first one of both the first pluralities of apertures of both the first and the second plenum plates, and a first fuel element standoff spool being disposed about a portion of the fuel element flow tube that is disposed between the first and the second plenum plates.

Abstract: A control drum system for a nuclear reactor including a reactor core, including an ex-core reflector including a plurality of cylindrical apertures, a plurality of control drum assemblies, each control drum assembly including a drive shaft, a drum cylinder affixed to a bottom end of the drive shaft, and a planetary gear attached to a top end of the drive shaft, wherein each drum cylinder is rotatably received in a cylindrical aperture, a first control drum drive motor operably connected to a first control drum assembly, and an annular ring gear that is operably connected to the planetary gear of each of the control drum assemblies so that all the control drum assemblies rotate simultaneously.

Abstract: A process for producing a titanium-molybdate material is provided. The process includes a step of reacting a metal molybdenum (Mo) material in a liquid medium with a first acid to provide a Mo composition and combining the Mo composition with a titanium source to provide a Ti—Mo composition. The Ti—Mo composition can be pH adjusted with a base to precipitate a plurality of Ti—Mo particulates.

Abstract: In a pressurized water reactor (PWR), emergency core cooling (ECC) responds to depressurization due to a vessel penetration break at the top of the pressure vessel by draining water from a body of water through an injection line into the pressure vessel. A barrier operates concurrently with the ECC to suppress flow of liquid water from the pressure vessel out the vessel penetration break. The barrier may comprise one or more of: (1) an injection line extension passing through the central riser to drain water into the central riser; (2) openings in a lower portion of a central riser to shunt some upward flow from the central riser into a lower portion of the downcomer annulus; and (3) a surge line providing fluid communication between a pressurizer volume at the top of the pressure vessel and the remainder of the pressure vessel which directs water outboard toward the downcomer annulus.

Abstract: In a pressurized water reactor (PWR), emergency core cooling (ECC) responds to depressurization due to a vessel penetration break at the top of the pressure vessel by draining water from a body of water through an injection line into the pressure vessel. A barrier operates concurrently with the ECC to suppress flow of liquid water from the pressure vessel out the vessel penetration break. The barrier may comprise one or more of: (1) an injection line extension passing through the central riser to drain water into the central riser; (2) openings in a lower portion of a central riser to shunt some upward flow from the central riser into a lower portion of the downcomer annulus; and (3) a surge line providing fluid communication between a pressurizer volume at the top of the pressure vessel and the remainder of the pressure vessel which directs water outboard toward the downcomer annulus.

Abstract: In a pressurized water reactor (PWR), emergency core cooling (ECC) responds to depressurization due to a vessel penetration break at the top of the pressure vessel by draining water from a body of water through an injection line into the pressure vessel. A barrier operates concurrently with the ECC to suppress flow of liquid water from the pressure vessel out the vessel penetration break. The barrier may comprise one or more of: (1) an injection line extension passing through the central riser to drain water into the central riser; (2) openings in a lower portion of a central riser to shunt some upward flow from the central riser into a lower portion of the downcomer annulus; and (3) a surge line providing fluid communication between a pressurizer volume at the top of the pressure vessel and the remainder of the pressure vessel which directs water outboard toward the downcomer annulus.

Abstract: A packing device for filling fuel elements with a powder through a fill aperture in an outer shell of the fuel element, including a stationary base, a clamp assembly including a body defining a bore therein, the bore being configured to slidably receive a fuel element therein, wherein the clamp assembly is movable along a vertical axis with respect to the stationary base, a cam assembly including a cam and a drive motor configured to rotate the cam, wherein rotation of the cam alternatingly raises the clamp assembly up along the vertical axis and subsequently drops the clamping assembly, and a powder reservoir assembly including a powder reservoir and a fill needle in fluid communication with the powder reservoir.

Abstract: Fission reactor has a shell encompassing a reactor space within which are a central longitudinal channel, a plurality of axially extending rings with adjacent rings defining an annular cylindrical space in which a first plurality of primary axial tubes are circumferential located. Circumferentially adjacent primary axial tubes are separated by one of the plurality of secondary channels and a plurality of webbings connects at least a portion of the plurality of primary axial tubes to adjacent structure. A fissionable nuclear fuel composition is located in at least some of the plurality of secondary channels and a primary coolant passes thorough at least some of the primary axial tubes. Additive and/or subtractive manufacturing techniques produce an integral and unitary structure for the fuel loaded reactor space. During manufacturing and as-built, the reactor design can be analyzed using a computational platform that integrates and analyzes data from in-situ monitoring during manufacturing.

Abstract: A process for producing a titanium-molybdate material is provided. The process includes a step of reacting a metal molybdenum (Mo) material in a liquid medium with a first acid to provide a Mo composition and combining the Mo composition with a titanium source to provide a Ti—Mo composition. The Ti—Mo composition can be pH adjusted with a base to precipitate a plurality of Ti—Mo particulates.

Abstract: A process for producing a metal-molybdate material is provided. The process includes a step of reacting a metal molybdenum (Mo) material in a liquid medium with a first acid to provide a Mo composition and combining the Mo composition with a metal source to provide a metal-Mo composition. The metal-Mo composition can be pH adjusted with a base to precipitate a plurality of metal-Mo particulates.

Abstract: A nuclear reactor includes a reactor core disposed in a reactor pressure vessel. A radiological containment contains the nuclear reactor and includes a concrete floor located underneath the nuclear reactor. An ex vessel corium retention system includes flow channels embedded in the concrete floor located underneath the nuclear reactor, an inlet in fluid communication with first ends of the flow channels, and an outlet in fluid communication with second ends of the flow channels. In some embodiments the inlet is in fluid communication with the interior of the radiological containment at a first elevation and the outlet is in fluid communication with the interior of the radiological containment at a second elevation higher than the first elevation. The radiological containment may include a reactor cavity containing a lower portion of the pressure vessel, wherein the concrete floor located underneath the nuclear reactor is the reactor cavity floor.

Abstract: A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactor cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.

Abstract: A nuclear reactor includes at least: a pressure vessel including an upper vessel section and a lower vessel section connected by a mid-flange and containing primary coolant; a nuclear reactor core disposed in the lower vessel section and immersed in the primary coolant; and upper internals suspended from the mid-flange of the pressure vessel. The upper internals include at least internal CRDMs immersed in the primary coolant and control rod guide frames. To refuel, the nuclear reactor is depressurized. The upper vessel section is disconnected and removed while leaving the mid-flange in place with the upper internals remaining suspended from the mid-flange. The mid-flange is then removed with the upper internals remaining suspended from the mid-flange. The fuel is replaced, the mid-flange is placed back onto the lower vessel section with the upper internals remaining suspended from the mid-flange, and the upper vessel section is placed back and re-connected.

Abstract: A nuclear reactor is supported by a primary support anchored to a civil structure and defining a reactor support plane located below the center of gravity of the nuclear reactor. A lateral seismic support engages the nuclear reactor below the reactor support plane to prevent lateral motion of the nuclear reactor. In one approach a flange, protrusion, or ledge of the reactor pressure vessel rests on a support engagement surface, a seismic rotational restraint assembly prevents the nuclear reactor from rotating during a seismic event, and a liftoff prevention assembly prevents vertical liftoff of the flange, protrusion, or ledge of the reactor pressure vessel from the support engagement surface. The lateral seismic support may comprise a pin connected with the bottom of the reactor pressure vessel engaging a pin socket connected with or formed in a floor of the civil structure of the radiological containment containing the nuclear reactor.

Abstract: A nuclear reactor includes a reactor core disposed in a reactor pressure vessel. A radiological containment contains the nuclear reactor and includes a concrete floor located underneath the nuclear reactor. An ex vessel corium retention system includes flow channels embedded in the concrete floor located underneath the nuclear reactor, an inlet in fluid communication with first ends of the flow channels, and an outlet in fluid communication with second ends of the flow channels. In some embodiments the inlet is in fluid communication with the interior of the radiological containment at a first elevation and the outlet is in fluid communication with the interior of the radiological containment at a second elevation higher than the first elevation. The radiological containment may include a reactor cavity containing a lower portion of the pressure vessel, wherein the concrete floor located underneath the nuclear reactor is the reactor cavity floor.

Abstract: A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactor cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.