A nuclear fuel assembly is constructed with fuel assembly components that are wire wrapped and positioned in hexagonal rings within a fuel assembly duct. The fuel assembly components positioned in an outermost ring of the fuel assembly are wire wrapped with a pitch that is shorter than fuel assembly components positioned at an interior ring of the fuel assembly. The shorter pitch at the outer ring of the fuel assembly increases pressure drop of a coolant fluid at the edge and corner subchannels and thereby reduces the temperature gradient across the fuel assembly, which provides a higher output temperature of the nuclear reactor without substantially increasing peak temperature of the fuel cladding.

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.

A nuclear fuel assembly is constructed with fuel assembly components that are wire wrapped and positioned in hexagonal rings within a fuel assembly duct. The fuel assembly components positioned in an outermost ring of the fuel assembly are wire wrapped with a pitch that is shorter than fuel assembly components positioned at an interior ring of the fuel assembly. The shorter pitch at the outer ring of the fuel assembly increases pressure drop of a coolant fluid at the edge and corner subchannels and thereby reduces the temperature gradient across the fuel assembly, which provides a higher output temperature of the nuclear reactor without substantially increasing peak temperature of the fuel cladding.

A nuclear reactor is constructed in sub-modules and super modules which are manufactured, packaged, and shipped to a construction site. At least some of the modules are packaged in suitable shielding containers or portions of containers, which may be steel. The modules are assembled on-site, and some of the modules remain within their respective shipping containers after assembly. One or more of the shipping containers may be used as concrete forms to support the pouring of concrete in between selected modules. The concrete may be used for structural support, shielding, or both.

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).

An improved retention and alignment system for nuclear fuel rods includes an upper nozzle plate and a lower nozzle plate, nuclear fuel rods, each having an upper end and a lower end and extending axially between the upper and lower nozzle plates, a first precision magnet incorporated onto the lower end of the fuel rod, and a plurality of second precision magnets incorporated onto the lower nozzle plate in positions confronting the first precision magnets on the fuel rods. Each first precision magnet has at least one of a magnetic north or south polarity and the second precision magnet has at least one of a magnetic south or north polarity opposite the polarity of the confronting first precision magnet to effect magnetic attraction between the confronting first and second precision magnets. Grids between the upper and lower nozzle plates form cells through which the fuel rods pass. Precision magnets of the same polarity may be positioned laterally along the fuel rods and grid walls in positions confronting each other to repel the fuel rods from the grid walls to maintain fuel rod alignment and prevent contact between the fuel rods and the grids.

An improved retention and alignment system for nuclear fuel rods includes an upper nozzle plate and a lower nozzle plate, nuclear fuel rods, each having an upper end and a lower end and extending axially between the upper and lower nozzle plates, a first precision magnet incorporated onto the lower end of the fuel rod, and a plurality of second precision magnets incorporated onto the lower nozzle plate in positions confronting the first precision magnets on the fuel rods. Each first precision magnet has at least one of a magnetic north or south polarity and the second precision magnet has at least one of a magnetic south or north polarity opposite the polarity of the confronting first precision magnet to effect magnetic attraction between the confronting first and second precision magnets. Grids between the upper and lower nozzle plates form cells through which the fuel rods pass. Precision magnets of the same polarity may be positioned laterally along the fuel rods and grid walls in positions confronting each other to repel the fuel rods from the grid walls to maintain fuel rod alignment and prevent contact between the fuel rods and the grids.

A nuclear fuel assembly having lateral support provided by a bimetallic spring that extends from a side of the fuel assembly under certain core conditions to pressure against an adjacent component and withdraws under other core conditions, such as shutdown, to enable the nuclear fuel assembly to be aligned or withdrawn from the core and repositioned.

A nuclear fuel assembly having lateral support provided by a bimetallic spring that extends from a side of the fuel assembly under certain core conditions to pressure against an adjacent component and withdraws under other core conditions, such as shutdown, to enable the nuclear fuel assembly to be aligned or withdrawn from the core and repositioned.

Methods of installing an external dashpot tube around a control rod guide tube in a nuclear reactor fuel assembly are disclosed herein. The nuclear reactor fuel assembly may include a top nozzle, a bottom nozzle, and a plurality of grids. The various methods may comprise inserting a guide tube into a skeleton of the nuclear reactor fuel assembly to a lower middle grid, the lower middle grid being second closest grid to the bottom nozzle of the plurality of grids. The various methods may also include installing an external dashpot tube over the guide tube after it has been inserted to the lower middle grid; inserting the guide tube with the installed external dashpot tube to the bottom nozzle; attaching the guide tube to the skeleton; and bulging the guide tube onto the external dashpot tube.