Numerical simulation of LOCA blow-down phase In-containment Refueling Water Storage Tank (IRWST) estimation and evalution of pH and iodine re-evolution during loss of coolant accident (LOCA) Nuclear power plant 3D CAD design [3D CAD Model and CFD analysis Results for KNGR Nuclear Reactor] [3D CAD Model and CFD analysis Results for KNGR Nuclear Reactor]