The radiation in harsh environments affects electronic systems, inducing permanent and temporary errors. These effects lead to unpredictable behaviors detrimental to critical applications and fail-safe systems. This work evaluates the reliability of a fault-tolerant RISC-V System-on-Chip (SoC) under atmospheric neutron irradiation in a particle accelerator. Prior work has analyzed the effectiveness of the hardening techniques of this SoC in simulation and provided a preliminary characterization in an irradiation facility. The applied hardening techniques showed a significant reliability improvement compared to the unhardened implementation of the SoC. The system executed a performance benchmark as workload, which finished correctly in most runs despite suffering from Single Event Effects (SEEs). This work presents a detailed analysis of the experimental results, reporting error rates and classification, extending the analysis given in previous works. Finally, a comprehensive discussion of implementation limitations and the proposition of further improvements are provided.