Elina Hujala

Local states of coolant flow play major roles during the normal operation and possible emergency conditions of a nuclear power plant (NPP). Although the thermal hydraulics of NPPs has been a popular research area, there is still demand for more uniform and generally applicable flow and heat transfer models. One part of that need is the reliable boundary surface modelling of liquid-vapour two-phase flow. The aim of this research is to create a mathematical model to define barrier layer of two-phase flow by using interfacial area transport theory. Interfacial area transport is a mathematical way to model a barrier layer between two different phases. It has been used to model two-phase flows of NPPs, but it is rarely measured in experimental research of NPP thermal hydraulics or used in improvement of system codes, albeit it could be very profitable in the both. With a functioning model, it could be possible to replace the simplified models in system codes, which would improve the quality of simulations, and improve also CFD interface modelling. It should also improve the analysis of the results of the NPP thermal hydraulics experiments and upgrade the safety research of light water reactors.