Theoretically Modified Optical Length Research on the Physical Boundary of the Double-Heterogeneous System

Lou, Lei; Chai, Xiaoming; Yang, Dong; Wang, Lianjie; Li, Mancang; Chen, Liang; Liu, Xiaoli; Li, Sinan; Xiao, Tang; Zhou, Nan

doi:10.3389/fenrg.2021.773067

Cited by 3 publications

(2 citation statements)

References 16 publications

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“…The reactivity deviation calculation of the volumetric homogenization method is related to many factors. For the dispersed particle fuel, whether the system needs to consider double heterogeneity can be judged by theoretically modified optical length (Lei et al, 2022), as shown in Eq (2).…”

Section: Relationship Between Self-shielding Effect and Theoretically...mentioning

confidence: 99%

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An improved optical length research on the physical boundary of particle-dispersed fuel

Liu,

Chen,

et al. 2024

Front. Energy Res.

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The Volumetric Homogenization Method (VHM) is one of the most commonly used methods for neutronics calculation in reactors or components. However, the use of VHM for the Double-Heterogeneous (DH) System may lead to a large deviation in reactivity calculation. The deviation of DH System using the VHM can be expressed by the theoretically modified optical length. When the theoretically modified optical length is less than 10−4, the deviation caused by the VHM will be less than 100 pcm. This paper points out that the existing theoretically modified optical length for some cases of DH systems is not accurate, and this method is only for pin cell. In this paper, by calculating a series of DH models and their corresponding VHM models, it is found that the water-uranium ratio and the shape of fuel region seriously affects the reactivity calculation deviation of particle-dispersed fuel, the original modified optical length does not take this into account, resulting in unacceptable errors. On this basis, the application of optical length to physical boundaries for DH system is further discussed and the shape correction factor is taken into consideration. Therefore, an improved optical length is proposed, which greatly expands the range of application of the physical boundary judgment methods for the double heterogeneity of dispersed particle fuel. The numerical results show that the accuracy of the improved optical length in defining the physical boundary of double heterogeneous system is higher than the theoretically modified optical length.

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Section: Relationship Between Self-shielding Effect and Theoretically...mentioning

confidence: 99%

“…The Nuclear Power Institute of China comprehensively considers the cross-section of dispersed particles and materials, particle size, and the mutual shielding effect between particles, and proposes the theoretically modified optical length (Lei et al, 2022) to define the DH physical boundary of the dispersed particle system.…”

Section: Introductionmentioning

confidence: 99%

An improved optical length research on the physical boundary of particle-dispersed fuel

Liu,

Chen,

et al. 2024

Front. Energy Res.

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Generation of particle self-shielded neutron cross-sections for the Monte-Carlo code TRIPOLI-4^®

Noguere,

Leconte,

Bernard

et al. 2024

EPJ Nuclear Sci. Technol.

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Self-shielding effects of micrometric particles randomly distributed in nuclear materials were the subject of extensive studies. These effects are known as a double-heterogeneity problem due to “microscopic” heterogeneities, involving the decrease of the neutron flux inside the particles, and “macroscopic” heterogeneities, affecting the neutron flux distribution over the entire volume containing those particles. The present study aims to take advantage of the capabilities of the GELINA facility (JRC-Geel, Belgium) in terms of non-destructive analysis of materials to validate experimentally any models developed to solve the double heterogeneity problem. In order to complement past experiments carried out at the GELINA facility, new transmission experiments were carried out on long cylindrical samples containing microspheres of Gd2O3 with diameters of 195 and 380 μm dispersed in UO2 pellets. The analysis of the experimental transmission spectra with the resonance shape analysis code REFIT and Monte-Carlo neutron transport code TRIPOLI-4® demonstrates that the particle self-shielding model proposed by Doub can reproduce the huge attenuation of the neutron absorption in the Gd resonances by reducing significantly the computational cost of Monte-Carlo simulations.

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Effects of Matrix Creep Properties on Effective Irradiation Swelling of U-10Mo/Zr Dispersion Nuclear Fuels

Zhang

Jian

et al. 2022

Front. Energy Res.

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A meso-mechanical model is established for the homogenized irradiation swelling of U-10Mo/Zr dispersion fuels, with an equivalent sphere chosen as the representative volume element (RVE). In the simulation, a mechanistic model for the fission gas swelling of U-10Mo particles and the creep model for Zr matrix with different values of the creep amplification factor are included. Based on the developed method, the results of effective irradiation swelling of U-10Mo/Zr dispersion fuels are obtained by finite element simulation. Additionally, the effects of matrix creep properties on the effective irradiation swelling are investigated. The numerical results indicate that 1) the Zr matrix has the function of restraining and compensating the irradiation swelling of fuel particles by the mechanical interactions between the fuel particles and the matrix; 2) with the increase in the creep amplification factor of the matrix, the effective irradiation swelling increases while the stresses in the fuel particles and the matrix decrease. The enhanced creep rate of the matrix is apt to result in less restraint of the effective irradiation swelling, but reduces the risk of radial crack initiation and propagation in the matrix; 3) based on the results of finite element simulation, a mathematic model for the effective irradiation swelling of U-10Mo/Zr dispersion fuels is fitted to correlate the effective irradiation swelling with different values of the matrix creep amplification factor under the considered irradiation conditions. The creep property of the matrix should be optimized because of its evident effects on the effective irradiation swelling and stresses of the U-10Mo/Zr dispersion fuels.

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Theoretically Modified Optical Length Research on the Physical Boundary of the Double-Heterogeneous System

Cited by 3 publications

References 16 publications

An improved optical length research on the physical boundary of particle-dispersed fuel

An improved optical length research on the physical boundary of particle-dispersed fuel

Generation of particle self-shielded neutron cross-sections for the Monte-Carlo code TRIPOLI-4^®

Effects of Matrix Creep Properties on Effective Irradiation Swelling of U-10Mo/Zr Dispersion Nuclear Fuels

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Theoretically Modified Optical Length Research on the Physical Boundary of the Double-Heterogeneous System

Cited by 3 publications

References 16 publications

An improved optical length research on the physical boundary of particle-dispersed fuel

An improved optical length research on the physical boundary of particle-dispersed fuel

Generation of particle self-shielded neutron cross-sections for the Monte-Carlo code TRIPOLI-4®

Effects of Matrix Creep Properties on Effective Irradiation Swelling of U-10Mo/Zr Dispersion Nuclear Fuels

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Product

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Generation of particle self-shielded neutron cross-sections for the Monte-Carlo code TRIPOLI-4^®