Abstract: Configurations of molten fuel salt reactors are described that allow for active cooling of the containment vessel of the reactor by the primary coolant. Furthermore, naturally circulating reactor configurations are described in which the reactor cores are substantially frustum-shaped so that the thermal center of the reactor core is below the outlet of the primary heat exchangers. Heat exchanger configurations are described in which welded components are distanced from the reactor core to reduce the damage caused by neutron flux from the reactor. Radial loop reactor configurations are also described.

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 nuclear fission reactor, flow control assembly, methods therefor and a flow control assembly system. The flow control assembly is coupled to a nuclear fission module capable of producing a traveling burn wave at a location relative to the nuclear fission module. The flow control assembly controls flow of a fluid in response to the location relative to the nuclear fission module. The flow control assembly comprises a flow regulator subassembly configured to be operated according to an operating parameter associated with the nuclear fission module. In addition, the flow regulator subassembly is reconfigurable according to a predetermined input to the flow regulator subassembly. Moreover, the flow control assembly comprises a carriage subassembly coupled to the flow regulator subassembly for adjusting the flow regulator subassembly to vary fluid flow into the nuclear fission module.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: Configurations of molten fuel salt reactors are described that utilize neutron-reflecting coolants or a combination of primary salt coolants and secondary neutron-reflecting coolants. Further configurations are described that circulate liquid neutron-reflecting material around an reactor core to control the neutronics of the reactor. Furthermore, configurations which use the circulating neutron-reflecting material to actively cool the containment vessel are also described.

Abstract: Disclosed embodiments include nuclear fission reactors, nuclear fission fuel pins, methods of operating a nuclear fission reactor, methods of fueling a nuclear fission reactor, and methods of fabricating a nuclear fission fuel pin.

Abstract: Illustrative embodiments provide a nuclear fission reactor, that includes a reactor vessel, a nuclear fission fuel element capable of generating a gaseous fission product, a valve body defining a plenum for receiving the gaseous fission product, and a valve in operative communication with the plenum for controllably venting the gaseous fission product from the plenum.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: Illustrative embodiments provide for the operation and simulation of the operation of fission reactors, including the movement of materials within reactors. Illustrative embodiments and aspects include, without limitation, nuclear fission reactors and reactor modules, including modular nuclear fission reactors and reactor modules, nuclear fission deflagration wave reactors and reactor modules, modular nuclear fission deflagration wave reactors and modules, methods of operating nuclear reactors and modules including the aforementioned, methods of simulating operating nuclear reactors and modules including the aforementioned, and the like.

Abstract: Illustrative embodiments provide for the operation and simulation of the operation of fission reactors. Illustrative embodiments and aspects include, without limitation, nuclear fission reactors and reactor modules, including modular nuclear fission reactors and reactor modules, nuclear fission deflagration wave reactors and reactor modules, modular nuclear fission deflagration wave reactors and modules, methods of operating nuclear reactors and modules including the aforementioned, methods of simulating operating nuclear reactors and modules including the aforementioned, and the like.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

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.

Abstract: A heat exchanger, methods therefor and a nuclear fission reactor system. The heat exchanger comprises a heat exchanger body defining an exit plenum chamber therein shaped for uniform flow of a hot primary heat transfer fluid through the chamber. A plurality of adjacent heat transfer members are connected to the heat exchanger body and spaced apart by a predetermined distance for defining a plurality of flow passages between the heat transfer members. The flow passages open into the exit plenum chamber. Spacing of the heat transfer members by the predetermined distance evenly distributes flow of the primary heat transfer fluid through the flow passages, across the surfaces of the heat transfer members and into the exit plenum chamber. Each heat transfer member defines a flow channel therethrough for flow of a cooler secondary heat transfer fluid.

Abstract: Disclosed embodiments include a vented nuclear fission fuel module system. Given by way of non-limiting example and not of limitation, an illustrative vented nuclear fission fuel module system includes a nuclear fission fuel element capable of generating a gaseous fission product. A valve body is associated with the nuclear fission fuel element, and the valve body defines a plenum therein for receiving the gaseous fission product. A reclosable valve is in operative communication with the plenum for controllably venting the gaseous fission product from the plenum, and the valve body includes a flexible diaphragm coupled to the valve for moving the valve to a closed position.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: The heat exchanger comprises a heat exchanger body defining an exit plenum chamber shaped for uniform flow of a hot primary heat transfer fluid through the chamber. A plurality of adjacent heat transfer members are connected to the heat exchanger body define a plurality of flow passages between the heat transfer members and open into the exit plenum chamber. Spacing of the heat transfer members by a predetermined distance evenly distributes flow of the primary heat transfer fluid through the flow passages, across the surfaces of the heat transfer members and into the exit plenum chamber. Heat transfer occurs from the hot primary heat transfer fluid to the cooler secondary heat transfer fluid as the primary heat transfer fluid flows through the chamber and as the secondary heat transfer fluid simultaneously flows through the flow channel of each heat transfer member.

Abstract: Disclosed embodiments include nuclear fission reactors, nuclear fission fuel pins, methods of operating a nuclear fission reactor, methods of fueling a nuclear fission reactor, and methods of fabricating a nuclear fission fuel pin.

Abstract: Disclosed embodiments include electromagnetic flow regulators for regulating flow of an electrically conductive fluid, systems for regulating flow of an electrically conductive fluid, methods of regulating flow of an electrically conductive fluid, nuclear fission reactors, systems for regulating flow of an electrically conductive reactor coolant, and methods of regulating flow of an electrically conductive reactor coolant in a nuclear fission reactor.

Abstract: Disclosed embodiments include methods of assembling a vented nuclear fission fuel module. Given by way of non-limiting example and not of limitation, an illustrative method of assembling a vented nuclear fission fuel module includes receiving a nuclear fission fuel element capable of generating a gaseous fission product. A valve body is coupled to the nuclear fission fuel element, and the valve body defines a plenum therein for receiving the gaseous fission product. A valve is disposed in communication with the plenum for controllably venting the gaseous fission product from the plenum. A flexible diaphragm is coupled to the valve for moving the valve. A cap is mounted on the valve, and a manipulator extendable to the cap for manipulating the cap is received.