An improved retention system for retaining fuel rods in a fuel assembly is disclosed. The retention system includes a plurality of first engagement surfaces on the bottom nozzle of a fuel assembly. There is at least one engagement surface for each fuel rod. A second engagement surface is formed on the bottom end plug of each fuel rod. The first and second engagement surfaces are configured for engagement with each other for axially and laterally retaining each fuel rod within the fuel assembly. Debris deflectors may also be provided to deflect debris from coolant channels surrounding the fuel rods.

A nuclear fuel assembly bottom end part debris filter has an inlet face (18A) and an outlet face (18B) opposed to the inlet face (18A) and comprises a plurality of filtering structures (50) protruding on the inlet face (18A) of the debris filter (18). Each filtering structure (50) has a structure base (52) and a structure apex (54) spaced along a structure axis (A), and each filtering structure (50) includes blades (56) distributed circumferentially around the structure axis (A). Each blade has one end connected to the structure base (52) and one end connected to the structure apex (54), and each blade (56) delimits a slot (58) with each adjacent blade (56) of the same filtering structure (50).

The fuel cartridge may include a plurality of fuel channels, a first header disposed on a first side of a fuel matrix, a second header disposed on a second side of the fuel matrix opposite to the first side, and a plurality of cooling tubes through which a working fluid flows. Each of the plurality of cooling tubes may pass through each corresponding cooling channel of the plurality of cooling channels, where each of the plurality of cooling tubes has a first end connected to the first header and a second end connected to the second header. The fuel cartridge may include an interior space for sealingly containing the fuel matrix may include a pressure boundary independent from an interior of the plurality of cooling tubes, such that the interior space is not in fluid communication with the plurality of cooling tubes.

The fuel cartridge may include a plurality of fuel channels, a first header disposed on a first side of a fuel matrix, a second header disposed on a second side of the fuel matrix opposite to the first side, and a plurality of cooling tubes through which a working fluid flows. Each of the plurality of cooling tubes may pass through each corresponding cooling channel of the plurality of cooling channels, where each of the plurality of cooling tubes has a first end connected to the first header and a second end connected to the second header. The fuel cartridge may include an interior space for sealingly containing the fuel matrix may include a pressure boundary independent from an interior of the plurality of cooling tubes, such that the interior space is not in fluid communication with the plurality of cooling tubes.

A getter element includes a getter material reactive with a fission product contained within a stream of liquid and/or gas exiting a fuel assembly of a nuclear reactor. At least one transmission pathway passes through the getter element that is sufficiently sized to maintain a flow of the input stream through the getter element at above a selected flow level. At least one transmission pathway includes a reaction surface area sufficient to uptake a pre-identified quantity of the fission product.

A mobile modular reactor, in particular, a graphite-moderated fission reactor, has an active core region and at least a portion of control region(s) that are located within an interior volume of a pressure vessel. Flow annulus features located in the flow annulus between an outer surface of the control rod/fuel rod and an inner surface of the cladding of the channel in which the rod is located stabilizes the flow annulus and maintains a reliable concentricity between the inner and outer claddings that envelope the flow annulus. Flow annulus features are equally circumferentially spaced at longitudinally separated locations and the flow annulus features at successive, longitudinally separated locations are rotationally offset relative to each other. For purposes of transportability, the pressure vessel is sized for mobile transport using a ship, train or truck, for example, by fitting within a shipping container.

A debris filter configured for a nuclear fuel assembly bottom end part includes a lower nozzle (8) and the debris filter (18) is supported by the lower nozzle (8). The debris filter (18) has an inlet face (18A) and an outlet face (18B) opposed to the inlet face (18A), and comprises at least one filtering section (18D) that has a retention capacity that increases gradually or stepwise towards from the inlet face (18A) to the outlet face (18B).

To provide is a fuel assembly capable of easily adjusting average MA enrichment in an inner blanket region. An inner core fuel assembly 7 loaded in an inner core region 2 of a core of a fast reactor includes a plurality of fuel rods 10 and a plurality of fuel rods 19. Each of the fuel rods 10 includes a lower core fuel region 12, an inner blanket region 11, and an upper core fuel region 13. A U—Pu—Zr metal fuel is disposed in the lower core fuel region 12 and the upper core fuel region 13, and a U—Zr metal fuel is disposed in the inner blanket region 11. Each of the fuel rods 19 includes a lower core fuel region 12, an inner blanket region 20, and an upper core fuel region 13. A U—Pu—Zr metal fuel is disposed in the lower core fuel region 12 and the upper core fuel region 13 of the fuel rod 19, and a MA-Zr metal fuel is disposed in the inner blanket region 20. By adjusting the number of the fuel rods 10 and the number of the fuel rods 19, MA enrichment in the inner blanket region 9 of the fuel assembly 7 can be easily adjusted.

Nuclear reactor fuel assembly comprising fuel elements installed in a frame having guide channels and spacer grids; a bottom nozzle; and a removable head. The head comprising collet tubes, an upper shell, a support element in the form of a tube, and springs. The collet tubes comprise two coaxially arranged tubes that are movable relative to each other and that each have stops on their side surfaces. The stops interact with each other to select the length of the collet tubes. The upper shell has a tube with a rigidly fixed plate interacting with the springs. The plate has plural holes having a shape corresponding to a shape of a respective boss of the support element. The clearance in plan view between a respective hole and a respective boss being at least the mounting clearance between the tube of the support element and the tube of the upper shell.

A nuclear fuel assembly comprises nuclear fuel rods (4) extending along a longitudinal axis (L) and a support skeleton (6) configured to support the nuclear fuel rods (4). The support skeleton (6) includes two end pieces (8, 10), a plurality of guide tubes (12) connecting the end pieces (8, 10) to each other, and spacer grids (14) attached to the guide tubes (12), with each spacer grid (14) supporting the nuclear fuel rods (4). The nuclear fuel assembly further includes at least one reinforcement device (20) comprising at least one reinforcement plate (22) which is in contact with at least two of the guide tubes (12) and attached to one or more of the guide tubes (12) at attachment points (21). Each reinforcement plate (22) has at least two attachment points (21) that are offset relative to each other along the longitudinal axis (L).