Development and validation of a new one-dimensional parallel transient system solver with coordinate transformation method developed in OpenFOAM.

• A one-dimensional two-phase six-equation solver based on OpenFOAM is developed. • A new coordinate transformation method for the simulation of one-dimensional system with bends in OpenFOAM was proposed. • Verification based on faucet problem was carried out with high accuracy. • Validation results based on passive containment cooling system showed good agreement and parallel speedup ratio. Passive containment cooling system is an important component of both 3rd and 4th generation nuclear power plants. To simulate two-phase flow in loop-type passive containment cooling system, a new one-dimensional parallel transient system solver, ComspaFOAM-SYS1D, was developed based on OpenFOAM. Compared to the previously developed one-dimensional solver, the new solver can be accelerated using multithreading. Additionally, a new coordinate transformation method was used in ComspaFOAM-SYS1D, enabling OpenFOAM to simulate a one-dimensional loop with bends. Faucet problem was used to verify the basic equations and models in the new solver. Validation was undertaken based on the GENEVA facility and the passive containment cooling system comprehensive performance test facility. In the assessments, representative parameters such as void fraction, pressure, temperature, phase velocity, and oscillation period were compared. Regarding efficiency, the simulation results indicated that the parallel speedup of the new solver could approach a value of approximately 2.0. In terms of accuracy, the relative deviations of time-averaged and transient extremum values of all the simulation results from the experimental results were within 15.0%. [ABSTRACT FROM AUTHOR]