Transient Analysis of Natural Circulation Nuclear Reactor REX-10

As research regarding small- and medium-sized nuclear reactors (SMRs) has rapidly increased worldwide, the Regional Energy Research Institute for Next Generation (RERI) is designing a new conceptual nuclear reactor, called the Regional Energy rX-10MW(t) (REX-10). The REX-10 is an integral-type nuclear reactor and adopts natural circulation for heat removal. Since the REX-10 is designed for district heating and small-scale power generation near residential areas, it has to guarantee safety under all circumstances. Thus, the REX-10 Test Facility (RTF) is designed to evaluate the natural circulation behavior in the REX-10. On the basis of a theoretical model and reactor safety, two experimental parameters (heater power and feedwater flow rate) were chosen and various transient experiments are conducted. As a result of six transient experiments, the RTF guarantees safety against abrupt changes in the experimental parameters. Furthermore, all the experiments are simulated by using the MARS code. In most cases, the results of the MARS code show good agreement with the experimental results. However, in case of the chiller trip, the MARS code overestimates the temperature and generates a fluctuation of the primary flow. However, both results show a similar trend after the fluctuation is finished.