Korea Atomic Energy Research Institute

Korea Hydro Nuclear Power Co., Ltd.

Texas State University

Kang-Hee Lee

Kyung-Ho Yoon

Jae-Yong Kim

Young-Ho Lee

Hyung-Kyu Kim

Kun-Woo Song

Dong-Seok Oh

Wang-Kee In

Tae-Hyun Chun

Chang Hwan Shin

Jong-Hun Kim

Dae-Ho Kim

Hyung Kyu Kim

Dong Seok Oh

Kun Woo Song

Wang Kee In

Kee-Nam Song

Tae Hyun Chun

Heung Seok Kang

Young Do Lee

Kyung-Jin Park

In-Hyouk Song

Byoung Hee You

Chang-Hwan Shin

Methods for forming a vertically movable gate field effect transistor (VMGFET) on a silicon-on-insulator (SOI) wafer are described. The methods include providing a process of making VMGFET devices without critical alignment of masks between sequential etch and diffusion steps. The oxide layer of the SOI wafer is used for a self-limiting etch stop layer and for a sacrificial layer to form an insulating layer between a gate electrode and a substrate. The proper location of the gate electrode with respect to the source and drain junctions is insured by using a silicon gate structure as a mask layer for the diffusion process for defining the source and drain junctions.

Vertically movable gate field effect transistor (VMGFET) on a silicon-on-insulator (SOI) wafer and method of forming a VMGFET

A dual-cooled nuclear fuel rod and a method of manufacturing the same are provided. The nuclear fuel rod includes an outer cladding tube having a circular cross section, an inner cladding tube having an outer diameter smaller than an inner diameter of the outer cladding tube, and a length longer than the outer cladding tube, and located in parallel in the outer cladding tube, a pellet charged in a space between the outer and inner cladding tubes and generating energy by nuclear fission, and first and second end plugs coupling opposite ends of the outer cladding tube to stepped outer joints formed on outer circumferences of first ends thereof and coupling opposite ends of the inner cladding tube to stepped inner joints formed on inner circumferences of the first ends thereof.

Dual-cooled nuclear fuel rod having annular plugs and method of manufacturing the same

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 spacer grid for dual-cooling nuclear fuel rods arranged at a narrow interval. The spacer grid solves the problem in which, since the dual-cooling nuclear fuel rods are used to improve the cooling performance and stability of nuclear fuel and obtain high burnup and output, the outer diameter of each dual-cooling nuclear fuel rod is increased, and thus the gap between each dual-cooling nuclear fuel rod and the grid strap is decreased. The spacer grid includes first grid straps and second grid straps, which are crossed and arranged in transverse and longitudinal directions at regular intervals and have the shape of a flat strip, and support structures, which are fitted into the first and second grid straps around intersections of the first and second grid straps so as to support the dual-cooling nuclear fuel rods.

Spacer grid for dual-cooling nuclear fuel rods using intersectional support structures

A perforated plate support supports dual-cooled fuel rods, each of which has concentric outer and inner tubes and is coupled with upper and lower end plugs at upper and lower ends thereof, and guide thimbles, each of which is used as a passage for a control rod. The perforated plate support is formed as a support plate having the shape of a flat plate, which includes internal channel holes, each of which has a diameter corresponding to an outer diameter of the inner tube, guide thimble holes, each of which has a diameter corresponding to an outer diameter of the guide thimble, and sub-channel holes around each internal channel hole. The upper or lower end of the dual-cooled fuel rod is coupled to the support plate such that the outer diameter of the inner tube is matched with the diameter of the internal channel hole.

Perforated plate support for dual-cooled segmented fuel rod

A spacer grid can be applied to close-spaced nuclear fuel rods. The spacer grid is directed to solve the problem in which, as the outer diameter of each nuclear fuel rod increases due to the use of dual-cooled nuclear fuel rods for improving cooling performance and obtaining high combustion and high output power, the gap between the neighboring nuclear fuel rods is narrowed to thus make it impossible to use an existing spacer grid. The spacer grid is a combination of unit grid straps, each of which has supports for supporting each of the nuclear fuel rods set in a narrow array and has a sheet shape, which are combined with each other. The supports are located at positions shifted from the longitudinal central line of each unit grid strap toward sub-channels.

Spacer grid for close-spaced nuclear fuel rods

A grid strap includes a spacer grid spring that increases the conformal contact area with a fuel rod of a nuclear fuel rod assembly. The shape of the spacer grid spring is optimized, thereby increasing the elasticity of the spacer grid spring contacting the fuel rod, expanding the conformal contact area with a contact portion between the spacer grid spring and fuel rod to obtain uniform stress distribution, and reducing excessive plastic deformation of the spacer grid spring. Further, magnitude and distribution of contact pressure between the fuel rod and the spacer grid spring are improved, thereby reducing the possibility of fretting wear caused by contact between the fuel rod and the spacer grid spring. Lastly, the elastic behavior region of the spacer grid spring is expanded, so that the fuel rod can be reliably supported until the fuel rod expires despite changes in the supporting conditions of the fuel rod.

Spacer grid spring for increasing the conformal contact area with fuel rod

Growing community of inventors

Daejeon, South Korea

Kang-Hee Lee