**5. Conclusions**

A two-dimensional model of an FCM pellet with a homogenous distribution of TRISO particles was generated to simulate the thermal-mechanical performance of an FCM pellet. The UN kernel and bu ffer layers were subtracted because the kernel and bu ffer layer were separated from other coated layers and have little influence on the thermal-mechanical performance of the SiC layer and matrix, which has been proven by a high temperature gas cooled reactor. The interaction between the matrix and TRISO particle was considered, and the performance of SiC layer and matrix were calculated. The maximum matrix temperature increased rapidly at the beginning and was followed by a slower linear increase, which corresponded to the degradation of SiC thermal conductivity. The SiC matrix, including the non-fuel region and inner parts, su ffered a large hoop, which can break the SiC matrix. The maximum hoop stress of the SiC layers located in di fferent parts was about 180 MPa, which was much lower than the intrinsic strength of the SiC ceramics. The failure probability of the SiC layers was lower than 9 × <sup>10</sup>−5, which indicated that the structural integrity of the SiC layers was maintained. The integrity of the SiC layers is beneficial to the capacity of fission product retention.

**Author Contributions:** Conceptualization, P.C. and S.Q.; methodology, S.L.; software, S.L.; validation, Y.Z., Y.X. and S.G.; formal analysis, H.L.; investigation, X.Q.; resources, X.Q.; data curation, P.C.; writing—original draft preparation, S.L.; writing—review and editing, X.Q.; visualization, X.Q.; supervision, S.Q.; project administration, P.C.; funding acquisition, P.C.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
