A BWR fuel assembly is elongated along a fuel assembly axis and comprises a lower tie plate, an upper tie plate axially spaced from the lower tie plate, a bundle of fuel rods extending axially between the lower tie plate and the upper tie plate, and a tubular fuel channel extending from the lower tie plate to the upper tie plate with encasing the fuel rods. The fuel assembly comprises an interaction device mounted on the lower tie plate and configured to interact with the fuel channel. The interaction device has an inactive configuration and an active configuration.

The method includes assessing operational characteristics of the fuel assembly, the assessing including determining if the fuel assembly is to be placed in a controlled location in the reactor core, a controlled location being positioned adjacent to a control blade that is to be utilized, and configuring the sidewalls of the outer channel by making at least a first select sidewall of the outer channel a reinforced sidewall, the remaining sidewalls of the outer channel, other than the at least a first select sidewall, being non-reinforced sidewalls. The entirety of the reinforced sidewall as a whole is at least one of thicker and made from a material that is more resistant to radiation-induced deformation as compared to an entirety of the non-reinforced sidewalls.

The method includes assessing operational characteristics of the fuel assembly, the assessing including determining if the fuel assembly is to be placed in a controlled location in the reactor core, a controlled location being positioned adjacent to a control blade that is to be utilized, and configuring the sidewalls of the outer channel by making at least a first select sidewall of the outer channel a reinforced sidewall, the remaining sidewalls of the outer channel, other than the at least a first select sidewall, being non-reinforced sidewalls. The entirety of the reinforced sidewall as a whole is at least one of thicker and made from a material that is more resistant to radiation-induced deformation as compared to an entirety of the non-reinforced sidewalls.

A channel box in an embodiment includes a tubular portion. The tubular portion includes a first tubular layer, a second tubular layer, and an intermediate tubular layer. The first tubular layer contains silicon carbide as a major component. The second tubular layer is in parallel to and surrounds or is surrounded by the first tubular layer and contains silicon carbide fibers and silicon carbide complexed with the silicon carbide fibers. The intermediate tubular layer is disposed between the first tubular layer and the second tubular layer and contains a solid lubricant.

A channel box in an embodiment includes a tubular portion. The tubular portion includes a first tubular layer, a second tubular layer, and an intermediate tubular layer. The first tubular layer contains silicon carbide as a major component. The second tubular layer is in parallel to and surrounds or is surrounded by the first tubular layer and contains silicon carbide fibers and silicon carbide complexed with the silicon carbide fibers. The intermediate tubular layer is disposed between the first tubular layer and the second tubular layer and contains a solid lubricant.

A duct for a nuclear fuel assembly includes a tubular body and an elongated member. The tubular body has a sidewall with an inner face and an outer face and is configured to contain nuclear fuel within a fuel region. The elongated member extends from the outer face along at least a portion of the fuel region and has a contact surface configured to stabilize the duct during operation of the nuclear fuel assembly.

A duct for a nuclear fuel assembly includes a tubular body and an elongated member. The tubular body has a sidewall with an inner face and an outer face and is configured to contain nuclear fuel within a fuel region. The elongated member extends from the outer face along at least a portion of the fuel region and has a contact surface configured to stabilize the duct during operation of the nuclear fuel assembly.

A nuclear reactor core mechanical support bracket is disclosed. The support bracket includes a housing, a spring disposed internally within the housing, a shaft slidingly disposed within the housing and to engage the spring to compress and decompress the spring as the shaft travels in and out of the housing, a shaft travel pin to control the travel of the shaft, and a flange to mount the support bracket to a canister of a nuclear reactor. The shaft includes an inset configured to interface with a nuclear reactor core component.

A fuel core for a nuclear reactor in one embodiment includes an upper internals unit and a lower internals unit comprising nuclear fuel assemblies. The assembled fuel core includes an upper core plate, a lower core plate, and a plurality of channel boxes extending therebetween. Each channel box comprises a plurality of outer walls and inner walls collectively defining a longitudinally-extending interior channels or cells having a transverse cross sectional area configured for holding no more than a single nuclear fuel assembly in some embodiments. A cylindrical reflector circumferentially surrounds channel boxes and is engaged at opposing ends by the upper and lower core plates. Adjacent cells within each channel box are formed on opposite sides of inner walls such that the cells are separated from each other by the inner walls alone without any water gaps therebetween which benefits neutronics for some small modular reactor designs.

The fuel assembly includes at least one fuel rod and an outer channel with four sidewalls surrounding the fuel rod, the outer channel having a configuration based on a position of the fuel assembly within a core of the nuclear reactor, wherein at least a first select sidewall, of the four sidewalls of the outer channel, is a reinforced sidewall, the remaining sidewalls of the outer channel, other than the at least a first select sidewall, are non-reinforced sidewalls, the at least a first select sidewall being in a controlled location that faces and is directly adjacent to a control blade that is to be utilized in the nuclear reactor, wherein an entirety of the reinforced sidewall as a whole is at least one of thicker and made from a material that is more resistant to radiation-induced deformation as compared to an entirety of the non-reinforced sidewalls.