Korea Atomic Energy Research Institute

Other

Korea Hydro Nuclear Power Co., Ltd.

Korea Electric Power Corporation

Kyung Ho Yoon

Dong Seok Oh

Hyung Kyu Kim

Tae Soo Chun

Wang Kee In

Kee Nam Song

Heung Seok Kang

Youn Ho Jung

Young Ho Lee

Jae Yong Kim

Kang Hee Lee

Kun Woo Song

Chang Hoon Shin

Tae Hyun Chun

Wang Ki In

Gyung Jin Park

Dae Ho Kim

Ki Ju Kang

Yeon Ho Jung

Chang-Hwan Shin

Je Geon Bang

A truss-reinforced spacer grid and a method of manufacturing the same are provided, in which truss members having a small diameter are woven to form a truss structure surrounded by an external plate, and the truss structure is joined to the external plate to thereby improve the strength of the mechanical structure. The truss-reinforced spacer grid includes a truss structure in which horizontal trusses formed by horizontally weaving a plurality of truss members are vertically disposed at regular intervals, and an external plate is joined with ends of the horizontal trusses and surrounds the truss structure.

Truss-reinforced spacer grid and method of manufacturing the same

A spacer grid for nuclear fuel rods includes a plurality of unit spacer grids stacked one on top of another. Each unit spacer grid includes a plurality of unit spacer grid straps disposed at regular intervals in a row, and a plurality of fixing grid straps connected to respective opposite ends of the unit spacer grid straps so as to fix the unit spacer grid straps. Each unit spacer grid strap has convexities alternating with each other on opposite sides thereof at regular intervals, and at least one of the convexities has a diameter greater than the others. The unit spacer grids are rotated in one direction by a 90 or 180 degree angle when being stacked.

Unit spacer grid strap, unit spacer grid, and spacer grid for nuclear fuel rods

An intermediate end plug assembly for a segmented fuel rod can stably support the fuel rod to the end of its cycle even if an interval between the fuel rods becomes narrow due to application of a dual-cooled fuel rod, and reduce excess vibration induced by flows of interior and exterior channels of the dual-cooled fuel rod for obtaining high burnup and output. To this end, the fuel rod has a segmented structure so as to make its length short. A lower intermediate end plug includes at least one channel hole, through which a coolant flows into an internal channel of the fuel rod, so that a possibility of causing departure from nuclear boiling ratio (DNBR) of the dual-cooled fuel rod is reduced.

Intermediate end plug assembly for segmented fuel rod and segmented fuel rod having the same

Disclosed herein is a guide thimble of a nuclear fuel assembly, which is capable of improving the cooling performance and the stability of a nuclear fuel, preventing a flow split in dual-cooling nuclear fuel rod and guide thimble sub channels for obtaining high combustion degree and high power, and minimizing a neutron absorption section in a reaction degree region. Since the guide thimble having the dual tube type structure is adopted, a flow split in the fuel rod and guide thimble sub channels can be reduced, and the degradation in performance of nuclear fuel due to increase of a neutron absorption section can be prevented. In order for compatibility with an existing control rod, a typical guide tube is used as an inner guide thimble, and an outer guide thimble is provided outside the inner guide thimble. Thus, the guide thimble has the dual tube type structure as a whole, and is coupled to the upper and lower end fittings so that it can prevent a flow unbalance due to the flow split in the fuel rod and guide thimble sub channels.

Guide thimble of dual tube type structure nuclear fuel assembly

A lips-type multi-purposed spacer grid for supporting fuel rods within a nuclear fuel assembly is disclosed. In the spacer grid, the fuel rods are in contact with dimples and water strider-type springs in an equiangular surface contact manner. The spacer grid distributes load, applied to the springs, to the entire structure of its inner strips, thus reducing peak stress at the contact surfaces between the fuel rods and the springs and diminishing vibration of the fuel rods, and thereby reducing possible fretting wear of the fuel rods due to hydraulic vibration of the fuel rods. The spacer grid also enlarges the allowable elastic range of the springs, and allows the springs to soundly support the fuel rods by using residual spring force. The spacer grid has mixing blades capable of minimizing pressure loss and flow interference, so that the fuel rod cooling efficiency of the nuclear fuel assembly is improved.

Lips-type multi-purposed nuclear fuel assembly spacer grid

A side-slotted nozzle type double sheet spacer grid for nuclear fuel assemblies is disclosed. The spacer grid includes intersecting inner strips and four perimeter strips. Each inner strip has unit strip parts, each fabricated by integrating two unit sheet parts together into a single structure, such that the two unit sheet parts face each other and a nozzle type coolant channel is defined between the two unit sheet parts. Each perimeter strip is fabricated by integrating an inner thin sheet having the unit sheet parts with a flat outer thin sheet having a width corresponding to the width of the inner thin sheet into a single structure. The coolant channel has one or more outlets formed by cutting an upper portion of one of the two unit sheet parts of each unit strip part. Each unit sheet part has a slot longitudinally formed on each side surface of a spring that is projected from the unit sheet part to support a fuel rod within a four-walled cell. The spacer grid thus effectively deflects and mixes coolants together to improve the heat transfer effect between fuel rods and coolants, and enhances its strength to effectively resist laterally directed forces acting thereon, and remarkably improves spring performance of its fuel rod support parts, thus accomplishing desired soundness of the fuel assemblies.

Side-slotted nozzle type double sheet spacer grid for nuclear fuel assemblies

A spacer grid used for placing and supporting fuel rods in nuclear reactor fuel assemblies is disclosed. The spacer grid of this invention has a plurality of grid springs designed to have an optimal shape of their vertical support parts, thus reducing fretting wear of the fuel rods caused by contact of the fuel rods with the grid springs. The grid spring has a vertical support part and a fuel rod support part. The vertical support part includes upper and lower base parts extending downward and upward from the central portions of the top and bottom edges of an opening formed at the central portion of a unit strip, and two bridge parts branched from the upper base part and extending symmetrically downward until they are united at the lower base part. The fuel rod support part includes a conformal support part brought into surface contact with the external surface of a fuel rod. Two transverse connection parts extend outward from the opposite outside edges of the conformal support part while being specifically bent, and are integrated with the central portions of the inside edges of the two bridge parts into a single structure, thus connecting the fuel rod support part to the vertical support part.

Spacer grid for nuclear reactor fuel assemblies with grid springs maintaining conformal contact with fuel rods and enlarged elastic range

A spacer grid with H-springs for use in a nuclear reactor fuel assembly is disclosed. In the spacer grid, two sets of intersectional grid strips are arranged in sets at an angle to each other prior to being encircled by a plurality of perimeter strips, thus forming a plurality of four-walled cells individually placing and supporting an elongated fuel rod therein. A plurality of regularly spaced openings are formed on each of the grid strips and perimeter strips at portions corresponding to the cells. An H-shaped spring is set in each of the openings and has a specifically curved rib capable of being brought into conformal surface contact with a fuel rod placed in each of the cells. The H-shaped spring thus elastically supports the fuel rod. Two positioning dimples are provided on each of the strips at positions above and below each of the openings. The two positioning dimples are so specifically curved as to come into conformal surface contact with a fuel rod, thus elastically supporting the fuel rod in cooperation with the H-shaped springs.

Spacer grid with H-spring for fuel rods for use in nuclear reactor fuel

A grid with coolant deflecting channels for used in nuclear fuel assemblies is disclosed. In the grid, two sets of intersecting grid strips are arranged in sets at right angles to each other prior to being encircled by four perimeter strips, thus forming a plurality of four-walled cells individually placing and supporting an elongated fuel rod therein. Each of the grid strips is made up of two narrow sheets which are deformed at a plurality of regularly spaced portions to provide nozzle-type coolant deflecting channels. The channels individually have an upright Y-shaped or reversed Y-shaped configuration capable of so deflecting coolant as to mix low temperature coolant with high temperature coolant. The channels thus form a uniform temperature distribution within a fuel assembly. The channels are so inclined with respect to the axes of the fuel rods as to form wide and linear positioning springs at middle portions thereof. The middle portions of the channels thus individually have a dual function of a deflecting channel for coolant and a positioning spring for the fuel rods.

Growing community of inventors

Daejeon, South Korea

Kyung Ho Yoon