Original Article Prediction of ballooning and burst for nuclear fuel cladding with anisotropic creep modeling during Loss of Coolant Accident (LOCA) Jinsu Kim a , Jeong Whan Yoon a, * , Hyochan Kim b , Sung-Uk Lee b a Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea b ATF Technology Development Division, Korea Atomic Energy Research Institute, Daedeok-Daero 989-111, Yuseong-gu, Daejeon, 34057, Republic of Korea article info Article history: Received 4 March 2021 Received in revised form 9 April 2021 Accepted 15 April 2021 Available online 24 April 2021 Keywords: Loss of coolant accident Ballooning and burst Multi-physics nuclear fuel rod Zircaloy-4 cladding Anisotropic creep abstract In this study, a multi-physics modeling method was developed to analyze a nuclear fuel rod's thermo- mechanical behavior especially for high temperature anisotropic creep deformation during ballooning and burst occurring in Loss of Coolant Accident (LOCA). Based on transient heat transfer and nonlinear mechanical analysis, the present work newly incorporated the nuclear fuel rod's special characteristics which include gap heat transfer, temperature and burnup dependent material properties, and especially for high temperature creep with material anisotropy. The proposed method was tested through various benchmark analyses and showed good agreements with analytical solutions. From the validation study with a cladding burst experiment which postulates the LOCA scenario, it was shown that the present development could predict the ballooning and burst behaviors accurately and showed the capability to predict anisotropic creep behavior during the LOCA. Moreover, in order to verify the anisotropic creep methodology proposed in this study, the comparison between modeling and experiment was made with isotropic material assumption. It was found that the present methodology with anisotropic creep could predict ballooning and burst more accurately and showed more realistic behavior of the cladding. © 2021 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction In nuclear reactors such as Light Water Reactor (LWR), a nuclear fuel rod consists of pellets and a cladding. The pellets are made from uranium dioxide (UO 2 ) and generate heat energy through nuclear fission. The cladding prevents leakage of radioactive ma- terials and transfers heat generated from the pellets to outer coolant. The cladding is commonly made with Zircaloy-4 due to its high corrosion resistance, adequate strength, and low neutron ab- sorption rate [1]. In the design stage of the nuclear reactors, the cladding's structural safety in an accident condition such as Loss of Coolant Accident (LOCA) is critical concern because the cladding's core function is to prevent the radioactive material from leakage. In the LOCA, the temperature of the fuel rod increases continuously due to leakage of the coolant. Then, the cladding undergoes a large deformation due to the increased temperature and internal pres- sure and it finally bursts. This transient phenomenon is called ballooning and burst. At the same time, along with the interests in safety issue during the LOCA, there are also attempts to develop advanced nuclear reactor systems wherein the fuel rods are exposed more aggressive environment than current reactors [2]. Therefore, it is important to predict the cladding's thermo- mechanical behavior during the LOCA in designing the nuclear reactors and safety systems such as Emergency Core Cooling Sys- tem (ECCS). According to these considerations, there have been advances in modeling of the nuclear fuel behavior as discussed in a recent review paper by Van Uffelen et al. [3]. In order to predict the fuel rod's thermo-mechanical behavior during the transient situation, one of the useful approaches is to utilize numerical methods to simulate and analyze the behavior. For example, numerical modeling based on finite element method (FEM) is widely used to analyze the fuel rod's complex thermo- mechanical behavior. However, one of interesting features in the nuclear fuel analysis is that in-house codes are often developed and utilized instead of using commercial software. This would be due to numerous nuclear fuel specific factors and corresponding models. These factors affect the physics in the nuclear fuel rod, and are coupled by themselves (for example, temperature, deformation, * Corresponding author. E-mail address: [email protected] (J.W. Yoon). Contents lists available at ScienceDirect Nuclear Engineering and Technology journal homepage: www.elsevier.com/locate/net https://doi.org/10.1016/j.net.2021.04.020 1738-5733/© 2021 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). Nuclear Engineering and Technology 53 (2021) 3379e3397
Prediction of ballooning and burst for nuclear fuel cladding with anisotropic creep modeling during Loss of Coolant Accident (LOCA)
Jun 04, 2023
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