No abstract

Designing a novel scaled modular test facility as a part of an experiment for condensation heat transfer (CHT) in Small Modular Reactors (SMRs) is the main focus of this study. This facility will provide data to evaluate the scalability of models for predicting heat transfer in the passive containment cooling system (PCCS) of SMR. The nuclear industry recognizes SMRs as one of the future candidates for clean, economical, and safe energy generation. But licensing requires proper evaluation of the safety systems such as PCCS. The knowledge gap from the literature review showed a lack of high-resolution experimental data for scaling of PCCS and validation of computational fluid dynamics (CFD) tools. Also, presently available test data are inconsistent due to unscaled geometric and varying physics conditions. This inconsistency leads to inadequate test data benchmarking. This study fills up this research gap by developing three different diameters (100 , 200, and 400) vertical condensing test section with annular cooling for scale testing and analysis. Saturated steam is chosen as the working fluid with noncondensible gas (NCGs) like N, He, and air in different mass fractions. This facility adopted a pre-cooler unit for inlet steam conditioning and a post-cooler unit for condensate cooling. Next, high fidelity sensors, instruments, and data acquisition systems are installed and calibrated to set up the modular facility. Lastly, facility safety analysis and shakedown tests are performed.

No abstract

This paper presents the computational fluid dynamics (CFD) validation and scaling assessment of the condensation heat transfer (CHT) models in the presence of non-condensable gas for the passive containment cooling system (PCCS) of the small modular reactor (SMR). The STAR-CCM+ software with 3D scaled-down SMR containment geometries was used in CFD simulations with steam and non-condensable gas (NCG). The limitations and approximations of the previous studies were resolved to avoid scaling distortion and uncertainties. Air was used as the NCG gas with steam. The multi-component gas model was used to define the steam-NCG mixture, and the condensation-seed parameter was used as the source term for the fluid film model. Three different turbulence models were used to check the heat flux performances and temperature distributions on the coolant side. The heat flux was estimated from the axial coolant bulk temperature, which was identical to the test data reduction method. An implicit-unsteady numerical solver was applied to the conjugate heat transfer models between the gas, liquid, and solid regions. Detailed simulations were performed, and simulation results were validated with the measured parameters experimentally. The condensation heat transfer performance was quantified using non-dimensional numbers and compared for different scaled geometries to identify the scaling distortions.