TRANSIENT ANALYSIS OF THE NUSCALE POWER HELICAL-COIL STEAM GENERATOR TUBE RUPTURE USING RELAP5-3D

Abstract

Nuclear energy is the largest source of carbon-free electricity in the United States, making up 20 percent of the electricity generated in the United States. The United States is the second-largest energy-consuming country globally, with fossil fuels being the largest electricity-producing source. With Climate Change at the head of the world’s most difficult circumstances, it is evident that nuclear power is a crucial and significant source of carbon-free energy to combat this crisis. The NuScale Power SMR can provide a cost-effective and safe solution to further the expansion of nuclear energy throughout the United States and the world. The nature of the buoyancy-driven natural circulation cooling design of the reactor primary systems and the modularity and scalability power plant system provide the innovations and technology needed to do so. There are few tools like RELAP5-3D that allow for the thermal-hydraulic transient analysis of nuclear reactors. Due to the minimum amount of open literature available on the transient analysis of the NuScale Power SMR, RELAP5-3D has been utilized to perform the steady-state and a steam generator tube-rupture transient calculation. The benchmark experiment for thermal-hydraulic calculation codes, called Edward’s pipe blowdown experiment, was first modeled to understand the basics of a transient two-phase flow model. This experiment was performed to acquire the essential modeling skills and techniques to build the model and perform the calculations of the NuScale Power SMR using RELAP5-3D. The NuScale Power Small Modular Reactor (SMR) relies on buoyancy-driven natural circulation cooling to cool the reactor core and extract thermal energy for electricity generation. The natural convection phenomenon has been of research interest for many years. NuScale Power LLC has only developed the SMR in recent years, and this integral Pressurized Water Reactor (iPWR) is the first nuclear reactor to utilize this phenomenon. Therefore, there is an increased interest in performing the transient analysis of the thermal-hydraulics of this reactor to understand conditions in which the natural circulation cooling inside the reactor system may be disrupted. There have been minimal published resources on this topic to date, making this research necessary for the growth and future of SMRs and natural circulation cooling of nuclear reactors. The innovations and designs of the NuScale Power SMR have allowed for enhanced safety, cost, scalability, modularity, time of construction, ease of transportation, and standardized manufacturing process of SMRs and nuclear power plants. RELAP5-3D was utilized to develop the model of the NuScale Power