A rod transfer assembly has an outer rotating plug. A pick-up arm assembly extends from the outer rotating plug and includes a pivoting arm. An inner rotating plug is disposed off-center from and within the outer rotating plug and is rotatable independent of a rotation of the outer rotating plug. An access port rotating plug is disposed off-center from and within the inner rotating plug and is rotatable independent of rotation of the outer and inner rotating plugs. A pull arm extends from the access port rotating plug.

Systems and methods determine locations of moving equipment in an area holding components to be moved. Moving equipment can relocate relative to the holding area to pick up components in the holding area from an origin and deliver them to a desired location or orientation. The moving equipment includes a device emitting a signal that is detectable where it hits components or other structures in a straight line or known path from the moving equipment. A human or computer can determine a position the moving equipment in the holding area from such signals. Devices can operate with visible light generators including LEDs, incandescent or fluorescent bulbs, and lasers and including lenses or reflectors to shape the light into detectable and high fidelity configurations. Automation components including a hardware processor, controller, and detector can operate moving equipment based on detected light, without human interaction or as a verification in human operations.

There is provided a core of a boiling water reactor that can be operated without loading a new fuel assembly at an operation cycle before decommissioning. The core of the boiling water reactor includes multiple fuel assemblies loaded in a square lattice shape. The multiple fuel assemblies are arranged in the core based on the number of residence cycles of fuel assemblies laterally adjacent and longitudinally adjacent to a fuel assembly having the shortest loading period in core cross section. The arrangement of fuel assemblies is also based on the number of residence cycles of fuel assemblies diagonally adjacent to the fuel assembly having the shortest loading period.

Systems and methods determine locations of moving equipment in an area holding components to be moved. Moving equipment can relocate relative to the holding area to pick up components in the holding area from an origin and deliver them to a desired location or orientation. The moving equipment includes a device emitting a signal that is detectable where it hits components or other structures in a straight line or known path from the moving equipment. A human or computer can determine a position the moving equipment in the holding area from such signals. Devices can operate with visible light generators including LEDs, incandescent or fluorescent bulbs, and lasers and including lenses or reflectors to shape the light into detectable and high fidelity configurations. Automation components including a hardware processor, controller, and detector can operate moving equipment based on detected light, without human interaction or as a verification in human operations.

A molten salt reactor includes a nuclear reactor core for sustaining a nuclear fission reaction fueled by a molten fuel salt. A molten fuel salt control system removes a volume of the molten fuel salt from the nuclear reactor core to maintain a reactivity parameter within a range of nominal reactivity. The molten fuel salt control system includes a molten fuel salt exchange system that fluidically couples to the nuclear reactor core and exchanges a volume of the molten fuel salt with a volume of a feed material containing a mixture of a selected fertile material and a carrier salt. The molten fuel salt control system can include a volumetric displacement control system having one or more volumetric displacement bodies insertable into the nuclear reactor core. Each volumetric displacement body can remove a volume of molten fuel salt from the nuclear reactor core, such as via a spill-over system.

Refueling of a nuclear reactor (40) includes removing a fuel assembly (10). The removal method includes lowering a lifting tool (80) of a crane (44) onto a top of the fuel assembly. The lowered lifting tool including a plurality of downwardly extending elements (82) that surround and vertically overlap a portion (74) of a control rod assembly (70) extending above the top of the fuel assembly. The downwardly extending elements are locked with corresponding mating features (26) at the top of the fuel assembly to connect the lifting tool with the fuel assembly. The connected fuel assembly is moved into a spent fuel pool (42) using the crane, and the lifting tool is disconnected from the top of the fuel assembly by unlocking the downwardly extending elements from the corresponding mating features at the top of the fuel assembly.

The generation of a nuclear core loading distribution includes receiving a reactor core parameter distribution associated with a state of a reference nuclear reactor core, generating an initial fuel loading distribution for a simulated beginning-of-cycle (BOC) nuclear reactor core, selecting an initial set of positions for a set of regions within the simulated BOC core, generating an initial set of fuel design parameter values utilizing a design variable of each of the regions, calculating a reactor core parameter distribution of the simulated BOC core utilizing the generated initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core and generating a loading distribution by performing a perturbation process on the set of regions of the simulated BOC core to determine a subsequent set of positions for the set of regions within the simulated BOC core.

The generation of a nuclear core loading distribution includes receiving a reactor core parameter distribution associated with a state of a reference nuclear reactor core, generating an initial fuel loading distribution for a simulated beginning-of-cycle (BOC) nuclear reactor core, selecting an initial set of positions for a set of regions within the simulated BOC core, generating an initial set of fuel design parameter values utilizing a design variable of each of the regions, calculating a reactor core parameter distribution of the simulated BOC core utilizing the generated initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core and generating a loading distribution by performing a perturbation process on the set of regions of the simulated BOC core to determine a subsequent set of positions for the set of regions within the simulated BOC core.

A system for refueling a nuclear reactor is provided. The system includes a lower reactor vessel with a plurality of fuel rods and a plurality of control rods disposed therein, the lower reactor vessel further comprising an upper flange. An upper reactor vessel is provided which encloses a steam generator and a pressurizer, the upper reactor vessel further comprising a lower flange that matingly engages the upper flange of the lower reactor vessel. A transporter surrounds an outer surface of the upper reactor vessel, wherein the transporter is configured to translate the upper reactor vessel vertically toward and away from the lower reactor vessel and also to translate the upper reactor vessel horizontally toward or away from alignment with the lower reactor vessel.

Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MW .sub.e.