Plurality of layers form a nuclear fission reactor structure, each layer having an inner segment body, an intermediate segment body, and an outer segment body (each segment body separated by an interface). The layers include a plurality of cladding arms having involute curve shapes that spirally radiate outward from a radially inner end to a radially outer end. Chambers in the involute curve shaped cladding arm contain fuel compositions (and/or other materials such as moderators and poisons). The design of the involute curve shaped cladding arms and the composition of the materials conform to neutronic and thermal management requirements for the nuclear fission reactor and are of sufficiently common design and/or have sufficiently few variations as to reduce manufacturing complexity and manufacturing variability.

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.

Plurality of layers form a nuclear fission reactor structure, each layer having an inner segment body, an intermediate segment body, and an outer segment body (each segment body separated by an interface). The layers include a plurality of cladding arms having involute curve shapes that spirally radiate outward from a radially inner end to a radially outer end. Chambers in the involute curve shaped cladding arm contain fuel compositions (and/or other materials such as moderators and poisons). The design of the involute curve shaped cladding arms and the composition of the materials conform to neutronic and thermal management requirements for the nuclear fission reactor and are of sufficiently common design and/or have sufficiently few variations as to reduce manufacturing complexity and manufacturing variability.

A method is for manufacturing a nuclear fuel assembly (2) comprising nuclear fuel rods (4) arranged in a bundle and a skeleton (6) supporting the fuel rods (4). The method comprise the steps of inserting fuel rods (4) into the skeleton (6) to obtain a fuel assembly (2) and packaging the fuel assembly (2) in view of transportation. The steps are being performed in a same nuclear fuel assembly manufacturing plant (20), preferably in a same nuclear fuel assembly manufacturing building (60).

A spacer grid of a nuclear fuel assembly having a simple shape structure is proposed. The spacer grid includes square grid cells having respective inner walls and constituting a square lattice structure. Each of the grid cells includes a plurality of springs for elastically supporting a fuel rod. Each of the plurality of the springs has a fixed end along a vertical direction on each of the inner walls and a free end curvedly provided in a horizontal direction from the fixed end. The grid cells also include a plurality of flow channels each provided in the vertical direction to each of the grid cells and a plurality of mixing vanes each protrudingly provided in a downstream direction of cooling water flow at end parts of each of the grid cells.

A spacer grid of a nuclear fuel assembly having a simple shape structure is proposed. The spacer grid includes square grid cells having respective inner walls and constituting a square lattice structure. Each of the grid cells includes a plurality of springs for elastically supporting a fuel rod. Each of the plurality of the springs has a fixed end along a vertical direction on each of the inner walls and a free end curvedly provided in a horizontal direction from the fixed end. The grid cells also include a plurality of flow channels each provided in the vertical direction to each of the grid cells and a plurality of mixing vanes each protrudingly provided in a downstream direction of cooling water flow at end parts of each of the grid cells.

A layer protecting the surface of zirconium alloys used as materials for nuclear reactors is formed by a homogenous polycrystalline diamond layer prepared by chemical vapor deposition method. This diamond layer is 100 nm to 50 m thick and the size of the crystalline cores in the layer ranges from 10 nm to 500 nm. Maximum content of non-diamond carbon is 25 mol %, total content of non-carbon impurities is maximum up to 0.5 mol %, RMS surface roughness of the polycrystalline diamond layer has a value less than 40 nm and thermal conductivity of the layer ranges from 1000 to 1900 Wm.sup.1K.sup.1. Coating of the zirconium alloys surface with the described polycrystalline diamond layer serves as a zirconium alloys surface protection against undesirable changes and processes in the nuclear reactor environment.

Process for manufacturing a nuclear component comprising i) a support containing a substrate based on a metal (1), the substrate (1) being coated or not coated with an interposed layer (3) positioned between the substrate (1) and at least one protective layer (2) and ii) the protective layer (2) composed of a protective material comprising amorphous chromium carbide; the process comprising a step a) of vaporizing a mother solution followed by a step b) of depositing the protective layer (2) onto the support via a process of chemical vapor deposition of an organometallic compound by direct liquid injection (DLI-MOCVD).

Nuclear component comprising i) a support containing a substrate based on a metal, the substrate (1) being coated or not coated with an interposed layer (3) positioned between the substrate (1) and at least one protective layer (2) and ii) the protective layer (2) composed of a protective material comprising amorphous chromium carbide. The composite nuclear component manufactured by the process of the invention has improved resistance to oxidation, hydriding and/or migration of undesired material.

The invention also relates to the use of the nuclear component for combating oxidation and/or hydriding.

Process for manufacturing a nuclear component comprising i) a support containing a substrate based on a metal (1), the substrate (1) being coated or not coated with an interposed layer (3) positioned between the substrate (1) and at least one protective layer (2) and ii) the protective layer (2) composed of a protective material comprising amorphous chromium carbide; the process comprising a step a) of vaporizing a mother solution followed by a step b) of depositing the protective layer (2) onto the support via a process of chemical vapor deposition of an organometallic compound by direct liquid injection (DLI-MOCVD).

Nuclear component comprising i) a support containing a substrate based on a metal, the substrate (1) being coated or not coated with an interposed layer (3) positioned between the substrate (1) and at least one protective layer (2) and ii) the protective layer (2) composed of a protective material comprising amorphous chromium carbide. The composite nuclear component manufactured by the process of the invention has improved resistance to oxidation, hydriding and/or migration of undesired material.

The invention also relates to the use of the nuclear component for combating oxidation and/or hydriding.

Provided is an apparatus for fatigue testing a bulge tool having a WH-type skeleton, the apparatus including: a fixing bracket having tool holes penetrated through opposite sides thereof; a tool housing coupled to the tool hole of the fixing bracket and having the bulge tool inserted and installed therein; a moving rail installed at one side of the fixing bracket in a lengthwise direction of the tool housing and providing a reciprocating movement path facing the tool housing; a moving bracket reciprocating along the moving rail; a pusher protrudingly installed from the moving bracket toward the tool housing and moving in and out of the bulge tool; a measurement means installed between the pusher and the moving bracket, measuring a load applied to the bulge tool; and a drive means for generating power reciprocating the moving bracket on the moving rail.