Abstract: A modular nuclear reactor comprises a plurality of sections arranged in a pattern and a side reflector material surrounding the plurality of sections. Each section includes a tank comprising a front plate, a back plate, side plates, a top plate, and a bottom plate. A plurality of grid plates are located within the tank. Each grid plate comprises a plurality of apertures and is vertically separated from an adjacent grid plate. The tank further includes a plurality of fuel elements extending through each grid plate. A plurality of heat pipes extend through each grid plate, the top plate, and an upper reflector. Methods of forming the modular nuclear reactor are also disclosed.

Abstract: A modular nuclear reactor comprises a central portion comprising a plurality of structures. Each structure comprises a fuel material surrounded by an outer cladding material, the fuel material defining an annular space at a center portion of the fuel material, a heat pipe disposed in the annular space, and an inner cladding between the fuel material and the heat pipe. The modular nuclear reactor further comprises a side reflector disposed around the central portion. Related modular nuclear reactors and related methods are disclosed.

Abstract: Methods of producing plutonium-238 are disclosed. One method includes dissolving neptunium-237 in a nitric acid solution to produce a neptunium target solution, subjecting the neptunium target solution to neutron radiation to produce plutonium-238, and removing the plutonium-238 from the neptunium target solution. A second method includes exposing a solution of neptunium-237 to neutron radiation to produce plutonium-238, complexing the plutonium-238 with an organophosphorus compound, and separating the plutonium-238/organophosphorus compound complex from the solution of neptunium-237. A third method includes dissolving neptunium-237 to form a neptunium-237 target solution, exposing the neptunium-237 to thermal neutrons to produce plutonium-238, utilizing an organophosphorus compound to complex the plutonium-238 and the organophosphorus compound, extracting the plutonium-238/organophosphorus compound complex from the irradiated neptunium target solution, and recovering the plutonium-238.