Pressurizer transient model

In the nuclear power plants using pressurized water as the main coolant, it is necessary to maintain system pressure within prescribed limits. The volume of the main coolant expands and contracts with average temperature variations causing insurges and outsurges in the pressurizer volume. The pressurizer acts in a way to maintain coolant pressure within prescribed limits. Pressurizer equipped with spray and relief system and electric heating elements. The pressure is controlled by the increase in bubble populations through heating and/or flashing or steam condensation through water sprays. This activity analyses the transient behavior of the pressurizer in a WWER type pressurized water nuclear power plant. An analytical method is developed for predicting pressure and water level variations in pressurizer following in or onsurge processes. The analysis also takes into consideration the variation of the thermodynamic mass qualities inside the pressurizer. The results obtained are compared with RELAP5/Mod3 and RELAP5/Mod2 as valid codes. D'Auria's model (FFT method) is employed for this comparative analysis. (author)