[en] Inadvertent loading error can occur in a reactor core. Peaking factors of the core could be increased significantly due to the misplaced fuel assemblies. This event is a Condition III incident (an infrequent fault). Technically the cases of misplacing assembles is nearly infinite. Some typical cases need to be chosen for the incident analysis. The purpose of analysis is to affirm the ability of the online core monitoring system to detect the inadvertent loading. The method of the analysis is described in this paper. Most of the misloading can be detected by the online core monitoring system and eliminated by rearranging the core pattern. Some cases not detected still satisfy the safety requirements, which the nuclear enthalpy rise factor F_ΔH is less than the design limits. (authors)