Silicon carbide fiber-reinforced silicon carbide matrix (SiC-SiC) composites are being considered as components in light water reactor cores to improve accident tolerance, including channel boxes and fuel cladding. In the nuclear reactor environment, core components like a channel box will be exposed to neutron and other radiation damage and temperature gradients. To ensure reliable and safe operation of a SiC-SiC channel box, it is important to assess its deformation behavior under in-reactor conditions including the expected neutron flux and temperature distributions. In particular, this work has evaluated the effect of non-uniform dimensional changes caused by spatially varying neutron flux and temperatures on the deformation behavior of the channel box over the course of one year. These analyses have been performed using the fuel performance modeling code BISON and the commercial finite element analysis code Abaqus, based on fast flux and temperature boundary conditions that have been calculated using the neutronics and thermal-hydraulics codes Serpent and CTF, respectively. The dependence of dimensions and thermophysical properties on fast flux and temperature has been incorporated into the material models. These initial results indicate significant bowing of the channel box with a lateral displacement greater than 6.5 mm. The channel box bowing behavior is time dependent and driven by the temperature dependence of the SiC irradiation-induced swelling and the neutron flux/fluence gradients. The bowing behavior gradually recovers during the course of the operating cycle as the swelling of the SiC-SiC material saturates. However, the bending relaxation due to temperature gradients does not fully recover and residual bending remains after the swelling saturates in the entire channel box.

碳化硅纤维增强的碳化硅基体（SiC-SiC）复合材料被视为轻水反应堆堆芯中的组件，以提高事故耐受性，包括通道箱和燃料包壳。在核反应堆环境中，通道箱等核心组件将受到中子和其他辐射损伤以及温度梯度的影响。为了确保SiC-SiC通道盒的可靠和安全运行，重要的是评估其在反应堆内条件（包括预期的中子通量和温度分布）下的变形行为。特别是，这项工作评估了由空间中子通量和温度变化引起的尺寸不均匀变化对通道箱在一年中的变形行为的影响。这些分析是使用燃料性能建模代码BISON和商业有限元分析代码Abaqus进行的，它们是基于分别使用中子学和热工液压代码Serpent和CTF计算的快速通量和温度边界条件进行的。尺寸和热物理性质对快速通量和温度的依赖性已被纳入材料模型。这些初步结果表明，通道盒的明显弯曲，其横向位移大于6.5 mm。通道箱的弯曲行为是时间相关的，并受SiC辐照引起的溶胀的温度相关性和中子通量/注量梯度的驱动。随着SiC-SiC材料的溶胀饱和，在操作周期过程中弯曲性能逐渐恢复。