The present invention relates to a device adapted for producing energy by nuclear fission, the device comprising a core container of a core container material, which core container encloses an inner tubing of an inner tubing material, the inner tubing and/or the core container having an inlet and an outlet, the device further comprising a molten halide salt located in the core container or in the inner tubing, wherein the inner tubing comprises one or more sections consisting of single crystal corundum. The invention further relates to methods of controlling nuclear fission processes using the device and to the use of a corundum tube as a structural material in a nuclear fission device. The invention provides improved economy in molten salt nuclear fission processes.

A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an integral pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the integral pressurizer. The drive shaft passes through a vessel penetration of the pressure vessel that is at least large enough for the impeller to pass through.

A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an integral pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the integral pressurizer. The drive shaft passes through a vessel penetration of the pressure vessel that is at least large enough for the impeller to pass through.

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.

The invention relates to a nuclear reactor circuit that is capable of containing nuclear fuel-containing molten salt in a channel which is substantially vertically arranged and provides an up-down passage. The circuits can be used to build a modular reactor from removable, individual molten salt nuclear circuits one part of which (‘the channel’) has been placed in a critical configuration, wherein the channel contains a non-critical amount of nuclear material, but the channels together create the critical zone of the reactor core. The invention further relates to methods of operating a modular nuclear reactor circuit and a nuclear reactor.

A marine power structure includes a building structure adapted to float on a body of water having a water surface. The mobile structure is transportable to a deployment location. The marine power structure also includes a nuclear enclosure disposed within in the building structure with a nuclear reactor disposed therein. A primary coolant system is connected to the nuclear reactor permitting heat generated by the nuclear reactor to be transferred thereto. At least one stabilizer is provided. The stabilizer is adapted to engage the building structure. The at least one stabilizer assists to maintain the stability of the building structure at the deployment location.

A marine power structure includes a building structure adapted to float on a body of water having a water surface. The mobile structure is transportable to a deployment location. The marine power structure also includes a nuclear enclosure disposed within in the building structure with a nuclear reactor disposed therein. A primary coolant system is connected to the nuclear reactor permitting heat generated by the nuclear reactor to be transferred thereto. At least one stabilizer is provided. The stabilizer is adapted to engage the building structure. The at least one stabilizer assists to maintain the stability of the building structure at the deployment location.

A nuclear reactor has a core installed on a lower core plate and formed from multiple fuel assemblies, each fuel assembly including a structural cage assembly. The structural cage assembly has an upper end fitting, mid grids, and a lower end fitting (LEF). The LEF positions the fuel assembly using four locating pins located at each corner of the LEF. The pins position the fuel assembly laterally by mating with receiving holes in the lower core plate. The locating pins have a chamfered tip with a flat end. The chamfered tip allows for a greater positioning margin when installing the fuel assembly in the core by guiding the pins into holes in the lower core plate, and the flat tip provides strength and stability in case the assembly is inadvertently rested on the tip of the pin instead of the LEF pads.

Fuel bundles for a nuclear reactor are disclosed, and in some embodiments include a first fuel element including thorium dioxide; a second fuel element including uranium having a first fissile content; and a third fuel element including uranium having a second fissile content different from the first fissile content. Nuclear reactors using such fuel bundles are also disclosed, including pressurized heavy water nuclear reactors. The uranium having the different fissile contents can include combinations of natural uranium, depleted uranium, recycled uranium, slightly enriched uranium, and low enriched uranium.

An in-core instrumentation system for a reactor module includes a plurality of in-core instruments connected to a containment vessel and a reactor pressure vessel at least partially located within the containment vessel. A reactor core is housed within a lower head that is removably attached to the reactor pressure vessel, and lower ends of the in-core instruments are located within the reactor core. The in-core instruments are configured such that the lower ends are concurrently removed from the reactor core as a result of removing the lower head from the reactor pressure vessel.