This paper investigates the use of a high reliability microgrid to supply emergency electrical power to a nuclear facility following loss of offsite power accident. Majority of the nuclear facilities around the world utilize diesel generators (DGs) and battery banks as emergency power to back up the grid power supply. This power supply configuration represents the concept of the microgrid system. The research work proposes reliability improvement of the emergency power supply by introducing distributed energy sources and large-scale energy storage systems. The proposed system was modeled with reliability block diagrams (RBDs) and analyzed with Monte Carlo simulation (MCS) to evaluate the system's reliability in terms of loss of power supply probability (LPSP). The analysis takes into consideration the failure probability of the components combined with the power unavailability due to the intermittent energy sources. The results show that the proposed system reduces the LPSP.