Evaluation of Fretting Wear Behavior on the Simulated Supporting Structures of a Dual-Cooled Nuclear Fuel Rod

A dual-cooled fuel (i.e. annular fuel) has been proposed to substantially increase in power density and safety margins compared to a solid fuel in operating PWR plants. As this fuel rod has larger outer diameter than the conventional solid rod to accommodate sufficient internal flow, new supporting structure geometries should be designed and their reliabilities (i.e. vibration characteristics, fretting wear resistance, etc.) are also examined with both analytical and experimental methods. In this study, the supporting structure characteristics and fretting wear behaviors are analyzed and examined by using two kinds of simulated supporting structures that have embossing and cylindrical shapes. Their supporting structure characteristics were examined by using a specially designed test rig and their results were compared with that of analytical method. Also, fretting wear behaviors of simulated supporting structures were experimentally examined with considering the effect of contact shapes and their stiffness values. Based on the test results, the relationship between the supporting structure characteristics and their fretting wear behaviors was discussed in detail.

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Flow Induced Vibration and Fretting Wear: An Integrated Approach

5th International Symposium on Fluid Structure International, Aeroeslasticity, and Flow Induced Vibration and Noise ◽

10.1115/imece2002-32828 ◽

2002 ◽

Cited By ~ 1

Author(s):

D. V. Paramonov ◽

S. J. King ◽

M. Y. Young ◽

R. Y. Lu

Keyword(s):

Flow Field ◽

Fuel Assembly ◽

Nuclear Fuel ◽

Wear Behavior ◽

Vibration Response ◽

Fretting Wear ◽

Analysis Model ◽

Fuel Rod ◽

Safety Margins ◽

Test Loop

Fuel assemblies are exposed to severe thermal, mechanical and radiation loads during operation. Global core and local fuel assembly flow fields typically result in fuel rod vibration. Under certain conditions, this vibration, when coupled with other factors, might result in excessive cladding fretting wear. This phenomenon is of the concern for nuclear fuel designers, especially in light of the need for higher burnup, longer cycle lengths, and operational safety margins in fuel designs. Understanding of (1) the fretting wear margins for a particular nuclear fuel design, (2) the probability of a fuel assembly exposed to a particular set of thermal, mechanical, flow and radiation conditions being at risk of excessive wear, and (3) the factors affecting fretting wear resistance, are important in order to better guide design, testing, and operational flexibility. In this paper, an integrated method to estimate fretting margin of nuclear fuel is presented, including its formulation, benchmark against experimental data and example application to in-core conditions. The major features of the method are as follows: • flow and rod vibration response are coupled through a linear structural analysis model, • flow field is determined using a sub-channel thermal-hydraulic code, • wear progression is treated as a time-dependent process, through taking into account impact of resulting rod-to-support clearance, • a possibility of a fluid-elastic instability is accounted for. Supporting data on basic wear mechanisms, flow field and fuel assembly fretting wear behavior obtained at a number of experimental facilities at Westinghouse Electric Company and Atomic Energy of Canada Limited are also presented. These facility include: • VIPER hydraulic test loop data where vibration response and wear are measured under prototypical flow conditions, and • autoclave fretting-wear machine steam employed to determine fretting-wear coefficients of fuel rod and grid-support designs.

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Preliminary Study on the Fretting Wear Reliability of an Annular Nuclear Fuel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.2535 ◽

2012 ◽

Vol 706-709 ◽

pp. 2535-2539

Author(s):

Young Ho Lee ◽

Hyung Kyu Kim

Keyword(s):

Nuclear Fuel ◽

Wear Behavior ◽

Fretting Wear ◽

Test Results ◽

Flow Induced Vibration ◽

Primary Coolant ◽

Spacer Grids ◽

Safety Margins ◽

Power Densities ◽

Current Operating

Recently, a dual-cooled fuel (i.e. annular fuel) which is compatible with current operating PWR plants has been proposed in order to increase both power densities and safety margins. Due to the design concept that is compatible with current PWR plants, however, when compared with a current solid nuclear fuel it shows a narrow gap between fuel rods and needs to modify spacer grid shapes and their positions. Because a flow-induced vibration by fast primary coolant is inevitable phenomenon, it is necessary to examine the fretting wear behavior between an annular fuel and designed spacer grids. In this study, fretting wear has been performed to evaluate the wear resistance of the annular fuel by using specially designed spring and dimple of spacer grids that have a cantilever type and a hemispherical shape, respectively. At the spring specimen with relatively small stiffness value, fretting wear was initiated at both end regions and then proceeded gradually to center region. Based on the test results, the fretting wear behavior of annular fuel was compared with the current solid nuclear fuel and a comparative factor of its reliability was proposed.

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Fretting Wear Behavior of APMT Steel at 350°C for Reactor Fuel Cladding Application

MRS Advances ◽

10.1557/adv.2016.532 ◽

2016 ◽

Vol 1 (35) ◽

pp. 2495-2500

Author(s):

Thomas Winter ◽

James Huggins ◽

Richard Neu ◽

Preet Singh ◽

Chaitanya S. Deo

Keyword(s):

Nuclear Reactor ◽

Wear Behavior ◽

Sem Analysis ◽

Fretting Wear ◽

Pressurized Water Reactor ◽

Fuel Cladding ◽

Reactor Accident ◽

Pressurized Water ◽

Water Reactor ◽

Fuel Rod

ABSTRACTIn support of a recent surge in research to develop an accident tolerant reactor, accident tolerant fuels and cladding candidates are being investigated. Relative motion between the fuel rods and fuel assembly spacer grids can lead to excessive fuel rod wear and, in some cases, to fuel rod failure. Based on industry data, grid-to-rod-fretting (GTRF) has been the number one cause of fuel failures within the U.S. pressurized water reactor (PWR) fleet, accounting for more than 70% of all PWR leaking fuel assemblies. APMT, an Fe-Cr-Al steel alloy, is being examined for the I2S-LWR project as a possible alternative to conventional fuel cladding in a nuclear reactor due to its favorable performance under LOCA conditions. Tests were performed to examine the reliability of the cladding candidate under simulated fretting conditions of a pressurized water reactor (PWR). The contact is simulated with a rectangular and a cylindrical specimen over a line contact area. A combination of SEM analysis and wear & work rate calculations are performed on the samples to determine their performance and wear under fretting. While APMT can perform favorably in loss of coolant accident scenarios, it also needs to perform well when compared to Zircaloy-4 with respect to fretting wear.

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Fretting wear behavior of a nuclear fuel rod under a simulated primary coolant condition

Wear ◽

10.1016/j.wear.2013.01.067 ◽

2013 ◽

Vol 301 (1-2) ◽

pp. 569-574 ◽

Cited By ~ 24

Author(s):

Young-Ho Lee ◽

Hyung-Kyu Kim

Keyword(s):

Nuclear Fuel ◽

Wear Behavior ◽

Fretting Wear ◽

Primary Coolant ◽

Fuel Rod

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Effects of Nb Content and Heat Treatment on Fretting Wear Behavior of Ti-Nb Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.1846 ◽

2021 ◽

Vol 1016 ◽

pp. 1846-1850

Author(s):

Naoki Nishimura ◽

Eri Miura-Fujiwara ◽

Tohru Yamasaki

Keyword(s):

Corrosion Potential ◽

Wear Behavior ◽

Open Circuit ◽

Potential Difference ◽

Fretting Wear ◽

Wear Volume ◽

Test Machine ◽

Heat Treated ◽

Nb Content ◽

The Relationship

Ti-Nb alloys in deionized water and Hanks' balanced salt solution were investigated at 310K using a ball-on-disc type frictional test machine with a ZrO2 ball counterface. In this study, besides the fretting wear behavior of Ti-Nb alloys was investigated, the relationship between the microstructure and mechanical properties of the Nb-added Ti alloy was investigated, and the relationship between the composition and hardness on the fretting wear of the alloy will be clarified from the results of the wear volume and surface analysis of wear track. The results obtained from the frictional test indicate that the dynamic coefficient of friction converged to a constant value with time variation. Also, wear volume in HBSS was smaller than in water, and wear volume of heat-treated became smaller than As-Rolled. Microstructural observations suggest the scars of adhesive wear were observed. Comparing each morphology, the ratio of the peeling part was more significant in Ti-Nb alloys, which have α+β than in Ti-Nb alloys, which have only β. Moreover, the results of Open circuit potentiometry indicate that the corrosion potential difference increased with wear. This is most likely due to the passive film was damaged. Besides, the corrosion potential difference of β-Ti-Nb alloy heat-treated with HBSS is small. It is assumed that there is an influence of HBSS besides the fine structure.

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Optimization of Fretting Wear Parameters and Effect of High Temperature on Fretting Wear Behavior of Al6061 Alloy and Al6061-SiC Composite

Silicon ◽

10.1007/s12633-021-01172-7 ◽

2021 ◽

Author(s):

Mehak Nisar ◽

M. S. Charoo

Keyword(s):

High Temperature ◽

Wear Behavior ◽

Fretting Wear ◽

Al6061 Alloy

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Fretting Wear Behavior of Three Kinds of Rubbers under Sphere-On-Flat Contact

Materials ◽

10.3390/ma14092153 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2153

Author(s):

Tengfei Zhang ◽

Jie Su ◽

Yuanjie Shu ◽

Fei Shen ◽

Liaoliang Ke

Keyword(s):

Normal Force ◽

Wear Behavior ◽

Displacement Amplitude ◽

Fretting Wear ◽

Butadiene Rubber ◽

Force Frequency ◽

Sealing Performance ◽

Rubber Surface ◽

Sealing Materials ◽

Flat Contact

Rubbers are widely used in various fields as the important sealing materials, such as window seal, door seal, valve, pump seal, etc. The fretting wear behavior of rubbers has an important effect on their sealing performance. This paper presents an experimental study on the fretting wear behavior of rubbers against the steel ball under air conditions (room temperature at 20 ± 2 °C and humidity at 40%). Three kinds of rubbers, including EPDM (ethylene propylene diene monomer), FPM (fluororubber), and NBR (nitrile–butadiene rubber), are considered in experiments. The sphere-on-flat contact pattern is used as the contact model. The influences of the displacement amplitude, normal force, frequency, and rubber hardness on the fretting wear behavior are discussed in detail. White light profiler and scanning electron microscope (SEM) are used to analyze the wear mechanism of the rubber surface. The fretting wear performances of three rubbers are compared by considering the effect of the displacement amplitude, normal force, frequency, and rubber hardness. The results show that NBR has the most stable friction coefficient and the best wear resistance among the three rubbers.

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