Kepco Nuclear Fuel Co., Ltd.

Joo Young Ryu

Dong Geun Ha

Seong Soo Kim

Kyong Bo Eom

Jin Sun Kim

Sang Youn Jeon

Jung Min Suh

Joon Kyoo Park

Joo Hong Chun

Su Pil Ryu

Ba Leum Kim

Jae Ik Kim

Oh Joon Kwon

O Cheol Kwon

Hak In Lee

The present invention relates to a top nozzle and a nuclear reactor in which an in-core instrument, which is supposed to be inserted through a top head of a nuclear reactor, is inserted through a guide pin for an upper core plate. In a nuclear reactor including guide pins for aligning a top nozzle for a nuclear fuel assembly with an upper core plate of a nuclear reactor, a guide hole () is axially formed through the guide pins () and in-core instruments () are inserted through the guide holes ().

Nuclear fuel assembly top nozzle having in-core instrument insertion structure using an upper core plate hollow guide pin

The present invention relates to a lower end fitting for reducing flow resistance due to an in-core instrument in a nuclear fuel assembly, that is, a lower end fitting () having a plurality of flow holes for a nuclear fuel assembly, in which the flow holes () are formed under an assembly groove in which an instrumentation tube () for a nuclear fuel assembly is inserted, and at least two or more flow holes () are formed at a predetermined distance from the central axis (C) of the instrumentation tube ().

Lower end fixing body for improving flow path resistance of in-core detector

Disclosed herein is a spacer grid for a nuclear fuel assembly which is formed from grid strips of an improved structure, thus reducing flow-induced high-frequency vibration. The spacer grid has dimples or grid springs for supporting fuel rods and is formed from a plurality of grid strips assembled in a lattice shape to form lattice cells. Each of the grid strips has at least one slot formed in a planar portion of the grid strip separately from the dimple or grid spring. Therefore, characteristics of the vibration of the spacer grid can be set in a variety of different manners so that flow-induced high-frequency vibration can be reduced.

Spacer grid for nuclear fuel assembly for reducing high frequency vibration

Disclosed herein is a spacer grid for a nuclear fuel assembly. The spacer grid has dimples for supporting fuel rods and is formed from grid strips which are assembled in a lattice shape to form lattice cells. Each grid strip has at least one hole which is formed separately from the dimples. Therefore, when coolant is drawn into the fuel assembly, a pressure difference between opposite sides of the holes is reduced, and friction generated between cut edges of the holes and the coolant reduces the magnitude of the vibration and causes a damping effect, thus reducing flow-induced vibration. The hole formed in the grid strip function to widen the range of the frequency of the flow-induced vibration caused by vortex sheddings formed around the edges of the grid strip, thus reducing the possibility of the generation of resonance with the natural frequency of the spacer grid.

Spacer grid for nuclear fuel assembly for reducing flow-induced vibration

Growing community of inventors

Daejeon, South Korea

Joo Young Ryu