Abstract: A method for replacing a cesium trap includes freezing the cesium trap which partially contains cesium and is located within a shielded cell and. The cesium trap is then decoupled and removed from the shielded cell. A second cesium trap is inserted into the shielded cell and attached to the shielded cell.

Abstract: Methods and systems for stabilizing spent fuel assemblies from sodium-cooled nuclear reactors using Zamak are described herein. It has been determined that there is a synergism between Zamak and sodium that allows Zamak to form thermally-conductive interface with the sodium-wetted surfaces of the fuel assemblies. In the method, one or more spent fuel assemblies are removed from the sodium coolant pool and placed in a protective sheath. The remaining volume of the sheath is then filled with liquid Zamak. To a certain extent Zamak will dissolve and alloy with sodium remaining on the fuel assemblies. Excess sodium that remains undissolved is displaced from the sheath by the Zamak fill. The Zamak is then cooled until solid and the sheath sealed. The resulting Zamak-stabilized spent fuel assembly is calculated to have sufficient internal thermal conductivity to allow it to be stored and transported without the need for liquid cooling.

Abstract: Methods and systems for stabilizing spent fuel assemblies from sodium-cooled nuclear reactors using Zamak are described herein. It has been determined that there is a synergism between Zamak and sodium that allows Zamak to form thermally-conductive interface with the sodium-wetted surfaces of the fuel assemblies. In the method, one or more spent fuel assemblies are removed from the sodium coolant pool and placed in a protective sheath. The remaining volume of the sheath is then filled with liquid Zamak. To a certain extent Zamak will dissolve and alloy with sodium remaining on the fuel assemblies. Excess sodium that remains undissolved is displaced from the sheath by the Zamak fill. The Zamak is then cooled until solid and the sheath sealed. The resulting Zamak-stabilized spent fuel assembly is calculated to have sufficient internal thermal conductivity to allow it to be stored and transported without the need for liquid cooling.

Abstract: Sodium-cesium trap systems and methods for the simultaneous removal of both sodium (Na) and cesium (Cs) in gas are provided. The trap system includes a contacting vessel having an inlet and an outlet with carrier gas channeled therethrough. A heating system maintains a temperature gradient across the contacting vessel between a first temperature at the inlet and a second temperature at the outlet such that sodium and cesium contained within the carrier gas are condensed into liquid and the carrier gas exiting the vessel is substantially free of sodium and cesium.

Abstract: A nuclear reactor is configured with a primary coolant loop for transferring heat away from the nuclear reactor core. In a shutdown event, the primary coolant pump may stop pumping primary coolant through the reactor core, resulting in decay heat buildup within the reactor core. An inertial energy coast down system can store kinetic energy while the nuclear reactor is operating and then release the stored kinetic energy to cause the primary coolant to continue to flow through the nuclear reactor core to remove decay heat. The inertial energy coast down system may include an impeller and a flywheel having a mass. During normal reactor operation, the flowing primary coolant spins up the impeller and flywheel, and upon a shutdown event where the primary coolant pump stops pumping, the flywheel and impeller can cause the primary coolant to continue to flow during a coast down of the flywheel and impeller.

Abstract: A curvilinear electromagnetic pump is configured to follow a curve, such as by coupling multiple linear pump segments together that are offset by an angle with respect to each other. The curvilinear electromagnetic pump can curve within two dimensions, or within three dimensions. The curvilinear electromagnetic pump allows for more efficient arrangement of components and systems within a nuclear reactor vessel and allows a significantly reduced reactor vessel height as compared to a linear pump arranged vertically. The curvilinear electromagnetic pump may follow the curvature of the reactor vessel wall and may be entirely disposed near the bottom of the reactor vessel.

Abstract: A method for replacing a cesium trap includes freezing the cesium trap which partially contains cesium and is located within a shielded cell and. The cesium trap is then decoupled and removed from the shielded cell. A second cesium trap is inserted into the shielded cell and attached to the shielded cell.

Abstract: A method for replacing a cesium trap includes freezing the cesium trap which partially contains cesium and is located within a shielded cell and. The cesium trap is then decoupled and removed from the shielded cell. A second cesium trap is inserted into the shielded cell and attached to the shielded cell.

Abstract: Sodium-tin and sodium-tin-lead compositions have been identified and created that exhibit better reactivity characteristics (i.e., are less reactive) than sodium metal under the same conditions, making these compositions safer alternatives to sodium metal for use as a coolant. These compositions include compositions having at least 90% sodium (Na), from 0-10% lead (Pb) and the balance being tin (Sn).

Abstract: An integrated energy system includes a nuclear thermal plant situated on a nuclear site. The nuclear thermal plant produces thermal energy that is transported to a thermal energy storage system located outside the nuclear site. The thermal storage system is thermally coupled to a power generation system which is also remote to the nuclear site. By this arrangement, the nuclear thermal plant is isolated and decoupled from the power generation system. The nuclear thermal plant may supply thermal energy upwards of 800° C. or more to be stored at the thermal energy storage system until needed such as for industrial heat, power generation, or other uses. The thermal storage system is source agnostic, and one or more additional thermal energy generators, such as additional nuclear reactors, solar thermal plants, or other thermal energy generators can be coupled to a common thermal storage system and power generation system.

Abstract: Sodium-cesium trap systems and methods for the simultaneous removal of both sodium (Na) and cesium (Cs) in gas are provided. The trap system includes a contacting vessel having an inlet and an outlet with carrier gas channeled therethrough. A heating system maintains a temperature gradient across the contacting vessel between a first temperature at the inlet and a second temperature at the outlet such that sodium and cesium contained within the carrier gas are condensed into liquid and the carrier gas exiting the vessel is substantially free of sodium and cesium.

Abstract: Configurations of molten fuel salt reactors are described that include an auxiliary cooling system which shared part of the primary coolant loop but allows for passive cooling of decay heat from the reactor. Furthermore, different pump configurations for circulating molten fuel through the reactor core and one or more in vessel heat exchangers are described.

Abstract: Sodium-cesium trap systems and methods for the simultaneous removal of both sodium (Na) and cesium (Cs) in gas are provided. The trap system includes a contacting vessel having an inlet and an outlet with carrier gas channeled therethrough. A heating system maintains a temperature gradient across the contacting vessel between a first temperature at the inlet and a second temperature at the outlet such that sodium and cesium contained within the carrier gas are condensed into liquid and the carrier gas exiting the vessel is substantially free of sodium and cesium.

Abstract: A method for replacing a cesium trap includes freezing the cesium trap which partially contains cesium and is located within a shielded cell and. The cesium trap is then decoupled and removed from the shielded cell. A second cesium trap is inserted into the shielded cell and attached to the shielded cell.

Abstract: A control assembly for a nuclear reactor having a pump includes a duct having an inner volume and defining a coolant flow path, a plug fixed to the duct, a rod disposed within the inner volume and having a rod end that is configured to engage a neutron modifying material, a first piston disposed within the inner volume, slidably coupled to the duct, and coupled to the rod, and a biasing member coupled to the rod and the first piston. The biasing member is positioned to apply a biasing force that repositions the first piston, the rod, and the neutron modifying material in response to a loss of pump flow without scram condition.

Abstract: Sodium-tin and sodium-tin-lead compositions have been identified and created that exhibit better reactivity characteristics (i.e., are less reactive) than sodium metal under the same conditions, making these compositions safer alternatives to sodium metal for use as a coolant. These compositions include compositions having at least 90% sodium (Na), from 0-10% lead (Pb) and the balance being tin (Sn).

Abstract: Sodium-cesium trap systems and methods for the simultaneous removal of both sodium (Na) and cesium (Cs) in gas are provided. The trap system includes a contacting vessel having an inlet and an outlet with carrier gas channeled therethrough. A heating system maintains a temperature gradient across the contacting vessel between a first temperature at the inlet and a second temperature at the outlet such that sodium and cesium contained within the carrier gas are condensed into liquid and the carrier gas exiting the vessel is substantially free of sodium and cesium.

Abstract: Configurations of molten fuel salt reactors are described that include an auxiliary cooling system which shared part of the primary coolant loop but allows for passive cooling of decay heat from the reactor. Furthermore, different pump configurations for circulating molten fuel through the reactor core and one or more in vessel heat exchangers are described.

Abstract: A control assembly for a nuclear reactor having a pump includes a duct having an inner volume and defining a coolant flow path, a plug fixed to the duct, a rod disposed within the inner volume and having a rod end that is configured to engage a neutron modifying material, a first piston disposed within the inner volume, slidably coupled to the duct, and coupled to the rod, and a biasing member coupled to the rod and the first piston. The biasing member is positioned to apply a biasing force that repositions the first piston, the rod, and the neutron modifying material in response to a loss of pump flow without scram condition.

Abstract: In response to a change in a thermal operational parameter in a nuclear fission reactor, reactivity is controlled by driving a neutron absorption parameter modifying material to or from a region of the core of the nuclear fission reactor. The apparatus includes a driver material disposed in a first reservoir portion and a second reservoir portion of a first reservoir and connected by a first conduit. A high-Z material may be distributed in the driver material. The neutron absorption parameter modifying material is disposed in both a second reservoir and the second reservoir portion of the first reservoir. A portion of the neutron absorption parameter modifying material is in physical contact with a portion of the driver material in the second reservoir portion. The neutron absorption parameter modifying material is driveable by the driver material between the second reservoir portion and the second reservoir through a second conduit.