Finite element analysis of the mechanical behavior of a nuclear fuel assembly spacer grid

2019 ◽  
Vol 352 ◽  
pp. 110179
Author(s):  
Youngik Yoo ◽  
Kyounghong Kim ◽  
Kyongbo Eom ◽  
Seongki Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Behavior ◽  
Fuel Assembly ◽  
Nuclear Fuel ◽  
Spacer Grid ◽  
Element Analysis ◽  
Nuclear Fuel Assembly

Finite Element Model to Simulate the Spacer Grid Buckling Characteristics

2020 ◽  
Author(s):  
Youngik Yoo ◽  
Joongjin Kim ◽  
Kyongbo Eom ◽  
Hyeongkoo Kim
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fuel Assembly ◽  
Nuclear Fuel ◽  
Grid Cell ◽  
Element Model ◽  
Spacer Grid ◽  
Static Compression ◽  
Fuel Rod ◽  
Nuclear Fuel Assembly

Abstract The purpose of this study is to develop a finite element model that accurately describes the buckling behavior of a spacer grid. The spacer grid is the most important component of a nuclear fuel assembly and supports the fuel rod with a structurally sufficient buckling strength. Therefore, the development of a reliable spacer grid model is essential to evaluate the mechanical integrity of a nuclear fuel assembly. To achieve this objective, a three-dimensional finite element model was proposed to simulate the buckling characteristics and mechanical behavior of a PWR spacer grid. To simulate the exact mechanical properties of the spacer grid cell, the parameter values required for the model were determined by conducting a fuel rod drag test and spacer grid spring/dimple stiffness test. Finally, a spacer grid static compression test and dynamic impact test were performed according to the gap size of the spacer grid cell, and the model was verified by comparing the test and analysis results. The results obtained using the developed spacer grid finite element model agreed well with the mechanical test results, and it was confirmed that both the buckling characteristics and mechanical behaviors of the model were accurately simulated by the proposed model.

IMPACT ANALYSIS AND TEST FOR THE SPACER GRID ASSEMBLY OF A NUCLEAR FUEL ASSEMBLY

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1228-1234 ◽  
Author(s):  
KEE-NAM SONG ◽  
SANG-HOON LEE ◽  
SOO-BUM LEE
Keyword(s):  
Fuel Assembly ◽  
Nuclear Fuel ◽  
Impact Analysis ◽  
Test Results ◽  
Lateral Loads ◽  
Spacer Grid ◽  
Element Analysis ◽  
Nuclear Fuel Assembly ◽  
Crush Strength ◽  
Good Agreement

A spacer grid assembly is one of the main structural components of the nuclear fuel assembly for a Pressurized light Water Reactor (PWR). The spacer grid assembly supports and aligns the fuel rods, guides the fuel assemblies past each other during a handling and, if needed, sustains lateral seismic loads. The ability of a spacer grid assembly to resist these lateral loads is usually characterized in terms of its dynamic and static crush strengths, which are acquired from tests. In this study, a finite element analysis on the dynamic crush strength of spacer grid assembly specimens is carried out. Comparisons show that the analysis results are in good agreement with the test results to within about a 30 % difference range. Therefore, we could predict the crush strength of a spacer grid assembly in advance, before performing a dynamic crush test. And also a parametric study on the crush strength of a spacer grid assembly is carried out by adjusting the weld penetration depth for a sub-sized spacer grid, which also shows a good agreement between the test and analysis results.

Impact Analysis and Test on the Spacer Grid Assembly for PWRs

2005 ◽  
Vol 297-300 ◽  
pp. 1309-1314 ◽  
Author(s):  
Kee Nam Song ◽  
Kyung Ho Yoon ◽  
Heung Seok Kang ◽  
Kang Hee Lee
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fuel Assembly ◽  
Impact Analysis ◽  
Dynamic Buckling ◽  
Failure Behavior ◽  
Spacer Grid ◽  
Element Analysis ◽  
Water Reactors ◽  
Buckling Test

A spacer grid assembly is one of the main structural components of the fuel assemblies of Pressurized light Water Reactors. The spacer grid assembly is structurally required to have enough buckling strength under various kinds of lateral loads acting on the fuel assembly so as to keep the fuel assembly straight. The structural performance of the spacer grid assembly is characterized in terms of its dynamic crush strength, which is usually acquired from the test. In this study, a dynamic buckling test and a finite element analysis on the KAERI designed spacer grid assembly are carried out. The pendulum-type tester was used in the test. In the finite element analysis, we proposed an analysis methodology that could predict the dynamic failure behavior of the spacer grid assembly using a commercial finite element code ABAQUS/explicit with appropriate boundary conditions. As a result of the comparisons, the analysis result is in good agreement with the test result to within a 10% difference range. Therefore, we could predict the dynamic behaviors of a spacer grid assembly in advance before performing the dynamic buckling test.

Impact Analysis for the Egg-Crate Structure of a Nuclear Fuel Assembly by Using FEM

2007 ◽  
Vol 353-358 ◽  
pp. 2668-2671
Author(s):  
Kee Nam Song ◽  
Sang Hoon Lee ◽  
Jae Yong Kim
Keyword(s):  
Fuel Assembly ◽  
Nuclear Fuel ◽  
Impact Analysis ◽  
Lateral Loads ◽  
Spacer Grid ◽  
Element Analysis ◽  
Nuclear Fuel Assembly ◽  
Buckling Test ◽  
Crush Strength ◽  
Good Agreement

A spacer grid assembly is one of the main structural components of the nuclear fuel assembly of a Pressurized light Water Reactor (PWR). The spacer grid assembly supports and aligns the fuel rods, guides the fuel assemblies past each other during a handling and, if needed, sustains lateral seismic loads. The ability of a spacer grid assembly to resist these lateral loads is usually characterized in terms of its dynamic and static crush strengths, which are acquired from tests. In this study, a finite element analysis on the dynamic crush strength of spacer grid assembly specimens is carried out. Comparisons show that the analysis results are in good agreement with the test results within an 8 % difference range. Therefore, we could predict the crush strength of a spacer grid assembly in advance, before performing the dynamic buckling test. And also a parametric study on the crush strength of a spacer grid assembly is carried out by adjusting the weld penetration depth for a sub-sized spacer grid, which also shows a good agreement between the test and analysis results.

Stress Corrosion Cracking Life Estimation of Hold-Down Spring Screw for Nuclear Fuel Assembly

2005 ◽  
Vol 297-300 ◽  
pp. 1834-1839
Author(s):  
Seung Kee Koh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Corrosion ◽  
Nuclear Fuel ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Element Analysis ◽  
Nuclear Fuel Assembly ◽  
Primary Water ◽  
Critical Regions

Hold-down spring screw fractures due to primary water stress corrosion cracking were observed in nuclear fuel assemblies. The screw fastens hold-down springs that are required to maintain the nuclear fuel assembly in contact with upper core plate and permit thermal and irradiation-induced length changes. In order to investigate the primary causes of the screw fractures, the finite element stress analysis and fracture mechanics analysis were performed on the hold-down spring assembly. The elastic-plastic finite element analysis showed that the local stresses at the critical regions of head-shank fillet and thread root significantly exceeded the yield strength of the screw material, resulting in local plastic deformation. Preloading on the screw applied for tightening had beneficial effects on the screw strength by reducing the stress level at the critical regions, compared to the screw without preload. Calculated deflections and strains at the hold-down springs using the finite element analysis were in very close agreements with the experimentally measured deflections and strains. Primary water stress corrosion cracking (PWSCC) life of the Inconel 600 screw was predicted by integrating the Scott’s model and resulted in a life of 1.42years, which was fairly close to the field experience. Cracks were expected to originate at the threaded region of the screw and propagated to the opposite side of the spring, which was confirmed by the fractographic analysis of the fractured screws.

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