Korea Atomic Energy Research Institute

Other

Korea Hydro Nuclear Power Co., Ltd.

Korea Electric Power Corporation

Wang Kee In

Dong Seok Oh

Hyung Kyu Kim

Kyung Ho Yoon

Tae Hyun Chun

Heung Seok Kang

Kee Nam Song

Youn Ho Jung

Kun Woo Song

Tae Soo Chun

Chang Hwan Shin

Gyung Jin Park

Dae Ho Kim

Kyung-Ho Yoon

Dong-Seok Oh

Kang-Hee Lee

Kang Hee Lee

Jae-Yong Kim

Yeon Ho Jung

Young Do Lee

Chang-Hwan Shin

Je Geon Bang

A dual-cooled fuel rod's spacer grid with upper and lower dimples, including a blocking area of a flow passage that coolant flows through is reduced and dual-cooled fuel rods are supported, and reduces a turbulent flow of the coolant as well as vibrations of the dual-cooled fuel rods, thereby lessening fretting damage done to the rods. The spacer grid includes a plurality of unit grid straps, each of which includes a body disposed in a vertical direction, an upper dimple protruding from an upper portion of the body, and a lower dimple spaced apart from the upper dimple in a downward direction and protruding from a lower portion of the body. The unit grid straps form a grid structure that have inner grid holes into which the dual-cooled fuel rods are held, and the held dual-cooled fuel rods are each supported in four directions by the upper and lower dimples.

Dual-cooled fuel rod's spacer grids with upper and lower cross-wavy-shape dimple

A lower end plug for an annular nuclear fuel rod includes a support with a great slenderness ratio, a coolant inflow part with an inner inflow space and a plurality of inflow holes in a wall thereof so as to interact with the inflow space, coupled to a lower end of the annular nuclear fuel rod at an upper end thereof, and extending from an upper end of the support in a reverse conical shape such that the inflow space interact with an inner channel of the annular nuclear fuel rod, and a coupler extending from a lower end of the support and coupled with a handing tool of the annular nuclear fuel rod. Thus, although a bottoming phenomenon of the annular nuclear fuel rod occurs, the coolant can be supplied to the inner channel of the annular nuclear fuel rod through the inflow holes of the lower end plug.

Reverse conical lower end plug for an annular nuclear fuel rod

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.

Grid with nozzle-type coolant deflecting channels for use in nuclear

Growing community of inventors

Daejeon, South Korea

Wang Kee In