The Necessity of a New Type Test Rig for the Development of an Evaluation Method in Grid Fretting Problems

Conference · Sun Jul 01 04:00:00 EDT 2007

OSTI ID:21229287

Lee, Young-Ho; Kim, Hyung-Kyu ^[1]

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1. Korea Atomic Energy Research Institute, 150 Dukjin-dong Yuseong-gu Daejeon, 305-353 (Korea, Republic of)

A grid fretting problem is recognized as one of the most important degradation mechanisms even though the examination results of fretting experiments could be applied to the development and design of spacer grid structures. This is because it is difficult to develop a fretting wear model for a grid fretting problem due to the various wear mechanisms involved according to the mechanical and environmental variables, the contact condition with a spring/dimple and the material properties. A number of spring shapes has been developed in KAERI and their performance tests such as fretting wear, flow-induced vibration (FIV) tests, etc. have been carried out from a part unit to a full assembly scale. From the unit part fretting test results, one of the noticeable results is that the contacting force (normal load) was gradually decreased with increasing number of fretting cycles due to a depth increase and this behavior was closely related to the contacting spring shape. When considering the actual contact condition between a fuel rod and a spring/dimple, if a fretting wear progresses due to a FIV under a specific normal load exerted on the fuel rod by an elastic deformation of the spring, the contacting force between the fuel rod and dimple that are located in the opposite side should be decreased. Consequently, an evaluation of developed spacer grids against fretting wear damage should be performed with the results of 1x1 cell unit experiments because a contacting force is one of the most important variables that influences a fretting wear mechanism. The discussion was focused on the development procedure of a new test rig and its performance by using a 1x1 cell unit test rig. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 21229287
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
DAMAGE
DEFORMATION
DESIGN
EVALUATION
FUEL RODS
KAERI
NUCLEAR FUELS
PERFORMANCE
WEAR