Dong Yingxuan, Lv Junnan, Zuo Hong, Li Qun
State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, China.
Science and Technology on Reactor Fuel and Materials Laboratory, Nuclear Power Institute of China, Chengdu 610213, China.
Materials (Basel). 2022 Apr 29;15(9):3231. doi: 10.3390/ma15093231.
Under irradiation, dispersion nuclear fuel meat consists of a three-phase composite of fuel particles surrounded by an interaction layer dispersed within a metal matrix. Nonuniform swelling pressures are exerted on the matrix, generated by irradiation swelling of the fuel particles. As these are considerable, they can cause matrix failure, but they are difficult to calculate. In this paper, taking into account thermal expansion, nonuniform fission pores and the interaction layer, nonuniform irradiation swelling pressure has been formulated, based on the equivalent inclusion method. By means of doubly equivalent transformations, a porous fuel particle, surrounded by an interaction layer, which is under irradiation, can be simplified as a homogeneous particle with the eigenstrain. With the aid of Green's function, nonuniform irradiation swelling pressure can be numerically analyzed. The simulation results of swelling pressures are in good agreement with numerical calculations. Furthermore, several simplified examples have been given to investigate the factors of influence and the impact mechanisms. Conclusions are drawn that nonuniform irradiation swelling pressure can be analyzed numerically and adopted to explore matrix failure. It is identified that the number and locations of fission pores inside a fuel particle are key factors for nonuniformity of swelling pressures. The volatility of swelling pressures is aggravated by burnup, while the average values of swelling pressures are intensely affected by temperature. This work provides a perspective to investigate the strength and integrity of dispersion fuel meat under high burnup.
在辐照下，弥散核燃料芯块由三相复合材料组成，即燃料颗粒被分散在金属基体中的相互作用层所包围。燃料颗粒的辐照肿胀会在基体上产生不均匀的肿胀压力。由于这些压力相当可观，它们可能导致基体失效，但却难以计算。本文基于等效夹杂法，考虑热膨胀、非均匀裂变孔隙和相互作用层，推导了非均匀辐照肿胀压力。通过双重等效变换，一个被相互作用层包围且处于辐照下的多孔燃料颗粒可简化为一个具有本征应变的均匀颗粒。借助格林函数，可对非均匀辐照肿胀压力进行数值分析。肿胀压力的模拟结果与数值计算结果吻合良好。此外，还给出了几个简化示例来研究影响因素及其作用机制。得出的结论是，非均匀辐照肿胀压力可进行数值分析，并用于探究基体失效。确定了燃料颗粒内裂变孔隙的数量和位置是肿胀压力不均匀性的关键因素。燃耗会加剧肿胀压力的波动，而温度则对肿胀压力的平均值有强烈影响。这项工作为研究高燃耗下弥散燃料芯块的强度和完整性提供了一个视角。
