The High Flux Research Reactor (HFRR) is a 40 MW pool-type nuclear research reactor developed for neutron beam tube research, material and fuel irradiation studies, and advanced research using a cold neutron source. As a part of safety analyses, thermal-hydraulic transient analyses were carried out using the computer coder RELAP5 for the primary coolant system of the HFRR. This technical note presents various analyses that were carried out such as loss of normal electric power supply, loss of heat sink, main coolant pump seizure, inadvertent opening of a natural circulation valve, and loss-of-coolant accident considering breaks in the pump suction line and pump discharge line. It is demonstrated that fuel cooling is ensured and safety parameters are well within acceptable limits.