Operation and safety of light-water nuclear power plants and heat and power plants

The mathematical model is presented describing the non-steady state temperature field and the hydraulic conditions in the fuel elements of a WWER type reactor. The numerical solution is shown of the equations of mass, energy and momentum conservation. The differential equations are written in a differential form suitable for computer processing. The hydrodynamic and thermokinetic model considers the thermal equilibrium between the water and steam phases provided the steam contained in the liquid phase is always saturated to the given pressure value. The validity of the model is limited to the single-phase water flow and the two-phase water and steam flow; the single-phase steam flow cannot possibly be solved. (Oy)