Ren Qisen, Liu Yang, Fang Runjie, Wu Lixiang, Liu Weiqiang
Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
China Nuclear Power Technology Research Institute Co., Ltd., Shenzhen 518026, China.
Materials (Basel). 2025 Jun 5;18(11):2659. doi: 10.3390/ma18112659.
Nuclear fuel pellets are subject to stress for long periods during the in-pile operation, and this study on high-temperature creep performance is of great significance for predicting the in-pile behaviors and safety evaluation of fuel elements. In the present study, a mixture of ZrC (50 wt%), SiC (46 wt%), and Si (4 wt%) powder was ball-milled for 24 h and then evaporated to obtain ZrC-SiC composite material. ZrC-SiC composite was adopted as the matrix, with ZrO surrogate kernel TRSIO particles and dispersion coated particle fuel pellets prepared with different TRISO packing fractions using the Spark Plasma Sintering (SPS) process. This study on compressive creep performances was conducted under a temperature range of 1373-2073 K and a stress range of 5-250 MPa, elucidating the creep behavior and mechanism of dispersed coated particles fuel pellets, and obtaining the variation laws of key parameters such as creep stress exponents and activation energy with TRISO packing fraction. The results showed that creep stress exponents of the surrogate fuel pellets are between 0.89 and 2.12. The activation energies for high temperature-low stress creep (1873-2073 K, 5-50 MPa) are 457.81-623.77 kJ/mol, and 135.14-161.59 kJ/mol for low temperature high stress creep (1373-1773 K, 50-250 MPa). Based on the experimental results, a high-temperature creep model was established, providing a valuable reference for the research and application of a ceramic matrix dispersed with coated particle fuels.
核燃料芯块在堆内运行期间会长期承受应力，因此这项关于高温蠕变性能的研究对于预测燃料元件的堆内行为和安全评估具有重要意义。在本研究中，将ZrC（50 wt%）、SiC（46 wt%）和Si（4 wt%）粉末的混合物进行24小时球磨，然后蒸发以获得ZrC-SiC复合材料。采用ZrC-SiC复合材料作为基体，使用放电等离子烧结（SPS）工艺制备了含ZrO替代核TRSIO颗粒以及不同TRISO体积分数的弥散包覆颗粒燃料芯块。本研究在1373 - 2073 K的温度范围和5 - 250 MPa的应力范围内进行了压缩蠕变性能研究，阐明了弥散包覆颗粒燃料芯块的蠕变行为和机理，并获得了蠕变应力指数和活化能等关键参数随TRISO体积分数的变化规律。结果表明，替代燃料芯块的蠕变应力指数在0.89至2.12之间。高温低应力蠕变（1873 - 2073 K，5 - 50 MPa）的活化能为457.81 - 623.77 kJ/mol，低温高应力蠕变（1373 - 1773 K，50 - 250 MPa）的活化能为135.14 - 161.59 kJ/mol。基于实验结果，建立了高温蠕变模型，为陶瓷基体弥散包覆颗粒燃料的研究和应用提供了有价值的参考。
