This paper presents an analytical interpretation of electromagnetic interference between solid-bottom type open cable trays in a nuclear power plant under the assumption that an electric-line current is undesirably generated from a damaged cable in an open cable tray. Based on the superposition principle and Helmholtz's equation in conjunction with the separation of variables, we employ a mode-matching method to obtain analytical solutions to the postulated electromagnetic interference problem. Before conducting a mode-matching analysis, we investigate the radiating principle of the electric field interfering with a victim cable tray by deriving the array factor in consideration of an imaginary electric-line current. In addition, we characterize the electric fields with a propagating mode at an observation point in the victim cable tray using the derived expression of the electric field. Based on this, we validate the formulation and computation of our mode-matching method and then computationally investigate the strength and distribution of interfering electric fields in terms of the separation distances provided in regulatory guidance on the electrical independence of a nuclear power plant. Finally, we compute the strength and distribution of the interfering electric field at the observation point when the location of an electric-line current is modified. The results of the study provide us with the useful information to alleviate the electromagnetic interference between open cable trays in a nuclear power plant.