In a pressurized water reactor, overpressure necessary to limit the bulk boiling is maintained by a pressurizer. Therefore, evaluation of this component is very important. In this paper, a simple numerical model based on the non-equilibrium, multi-region model is employed to simulate the pressurizer behavior during transient conditions. Because of the important role of the scale, this model should be able to predict the behavior of a real power plant pressurizer precisely. In the present study, it is shown that if all of the phenomena occur in a pressurizer are coupled with an appropriate computation model, a good prediction could be acquired. Accordingly, the basic balances equations of mass and energy together with appropriate constitutive models are used to describe all the important phenomena inside the pressurizer. Furthermore, a pressurizer model is built using the TRACE thermal-hydraulic code. The developed model are then assessed against the different data from separate experiment tests conducted on MIT, PACTEL as well as a full-scale pressurizer. For all the cases, TRACE simulation results are also reported. It is shown that the agreement between the results is rather good for different sets of conditions. This confirms that the scale would not affect the accuracy of the model and that it can be successfully applied for analyzing a full-scale pressurizer.
