Design and pre-test analyses of an integral thermal–hydraulic facility for a prismatic gas-cooled micro reactor

To support the R&D of the novel gas-cooled micro reactor (GMR), an integral thermal–hydraulic test facility (named INTALI) is designed to explore the key thermal–hydraulic phenomena specific to the GMR, thereby providing necessary data to validate computer codes for thermal–hydraulic and accident transient analysis. This paper presents a preliminary design of the INTALI facility, experimental methodology, and pre-test analyses. The INTALI facility consists of a primary loop operating at the prototypical temperature and pressure and a test section containing a scaled-down simulated reactor and a passive core cooling system (PCCS). Steady-state and transient tests will be carried out, which correspond to the normal operation and the pressurized loss of forced coolant (PLOFC) accident condition of the GMR, respectively. The experiment is mainly to investigate: (i) the coupling between the reactor and the PCCS, especially during the PLOFC, (ii) the operational characteristics of the PCCS and the energy distribution, and (iii) potential thermal stratification in the gravitational direction caused by the natural circulation in the PCCS. The pre-test analyses of the experiment were performed by CFD simulations using the COMSOL Multiphysics software. The predicted 3D distributions of the temperature and velocity fields for both the reactor and the PCCS are used to determine the instrumentation scheme. The simulation results show that no significant vertical thermal gradient is observed on the RPV wall. The radiative heat transfer from the RPV to the PCCS insulation layer plays an important role in heat removal in addition to convection. The heat removal capability of the PCCS is significantly influenced by the RPV’s temperature during the PLOFC transient. The developed CFD model is also ready for post-test quantification and validation once the experimental data is available.