Abstract: A pressure-tube nuclear reactor can include an outer shell having an interior to contain a moderator at a first pressure and a coolant plenum to receive the coolant fluid at a second pressure, the second pressure being greater than the first pressure. The reactor also includes a plurality of pressure tubes. Each pressure tube is received within and extends through a corresponding shell tube and is configured to releasably retain at least one fuel bundle. A first end of each pressure tube being coupled to the plenum tubesheet in fluid communication with the plenum chamber and a second end of each pressure tube fluidly connected to a coolant conduit to enable the coolant fluid to flow between the coolant plenum and each pressure tube and to flow from the nuclear reactor for further processing.

Abstract: A nuclear fuel bundle may include a first end face and a second end face axially spaced apart from the first end face and a plurality of elongate nuclear fuel elements supported by at least one spacer. The plurality of fuel elements and spacer being sized to be removably received within the fuel channel assembly. A coolant tube passage may extend axially through the fuel bundle between a first aperture in the first end face and a second aperture in the second end face. The coolant tube passage sized to removably receive a coolant fluid downflow tube provided in the fuel channel assembly. The tube passage extending from the first end face to the second end face to enable the coolant fluid downflow tube to pass through the fuel bundle.

Abstract: A fuel channel assembly for a nuclear reactor may include an inner conduit received within an outer conduit that has an outer upper end connectable to a coolant outlet and an outer lower end. The inner conduit may have an inner upper end connectable to a coolant source and an inner lower end axially spaced apart from the inner upper end and disposed within the outer conduit to enable coolant to circulate from the coolant source to the coolant outlet through both the inner and outer conduits. A fuel bundle chamber may be between an inner surface of the outer conduit and an outer surface of the inner conduit and may at least partially laterally surround the inner conduit. The fuel bundle chamber fluidly connecting the inner lower end and the outer upper end to enable the coolant to flow upward through the fuel bundle chamber.

Abstract: A pressure-tube nuclear reactor can include an outer shell having an interior to contain a moderator at a first pressure and a coolant plenum to receive the coolant fluid at a second pressure, the second pressure being greater than the first pressure. The reactor also includes a plurality of pressure tubes. Each pressure tube is received within and extends through a corresponding shell tube and is configured to releasably retain at least one fuel bundle. A first end of each pressure tube being coupled to the plenum tubesheet in fluid communication with the plenum chamber and a second end of each pressure tube fluidly connected to a coolant conduit to enable the coolant fluid to flow between the coolant plenum and each pressure tube and to flow from the nuclear reactor for further processing.