Zhao Jian, Chen Zhenyue, Zhao Yunmei
School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China.
Materials (Basel). 2023 Mar 27;16(7):2644. doi: 10.3390/ma16072644.
A ceramic-ceramic (CERCER) fuel with minor actinide-enriched ceramic fuel particles dispersed in a MgO ceramic matrix is chosen as a promising composite target for accelerator-driven systems (ADS). Fission swelling is a complex irradiation-induced phenomenon that involves recrystallization, resolution, and hydrostatic pressure under extreme conditions of high temperature and significant fission flux. In this study, a multiscale computational framework was developed to integrate simulations of continuum-scale thermo-mechanical behavior in the CERCER composite with a grain-scale hydrostatic pressure-dependent fission gas swelling model. Hydrostatic pressure-dependent fission welling is taken into account in the stress update algorithms for UO2 particles. Accordingly, we programmed the user subroutines to define the thermo-mechanical constitutive relations in the finite element simulations. The obtained results indicate that (1) the proposed method accurately predicts the swelling deformation at various burnup levels while taking into account hydrostatic pressure and (2) prior to recrystallization, the particle swelling is primarily influenced by temperature variation, whereas after recrystallization, the presence of hydrostatic pressure favorably suppresses the swelling deformation. This work effectively captures the swelling behavior influenced by hydrostatic pressure within the dispersed-type CERCER composite fuel in ADSs.
一种陶瓷-陶瓷（CERCER）燃料被选为加速器驱动系统（ADS）有前景的复合靶材，该燃料含有分散在MgO陶瓷基体中的富含次锕系元素的陶瓷燃料颗粒。裂变肿胀是一种复杂的辐照诱导现象，涉及在高温和高裂变通量的极端条件下的再结晶、溶解和静水压力。在本研究中，开发了一个多尺度计算框架，将CERCER复合材料中连续尺度热机械行为的模拟与基于晶粒尺度静水压力的裂变气体肿胀模型相结合。在UO2颗粒的应力更新算法中考虑了与静水压力相关的裂变肿胀。因此，我们编写了用户子程序，以定义有限元模拟中的热机械本构关系。所得结果表明：（1）所提出的方法在考虑静水压力的情况下，准确预测了不同燃耗水平下的肿胀变形；（2）在再结晶之前，颗粒肿胀主要受温度变化影响，而在再结晶之后，静水压力的存在有利地抑制了肿胀变形。这项工作有效地捕捉了ADS中分散型CERCER复合燃料中受静水压力影响的肿胀行为。
