The pressurized water reactor is the most common type of reactor in today's nuclear power plants. Although the basic design remains unchanged, there are variations in the detailed design by different reactor manufacturers. 

Compared to a boiling water reactor, the PWR has a more compact core and a higher system pressure. There is no equipment for steam separation in the reactor vessel since the water does not boil in the core. 

Due to the fact it is the most common type of reactor, it was necessary to learn how to create a model of this type of reactor for future purposes in safety analyses which are to be performed by our department.

The software chosen to fulfil this need was CATHARE, a French system code specifically developed to model whole nuclear power plant system. Validation of the code was done on numerous experiments, facilities and operating power plants. CATHARE has been used in multiple applications ranging from safety analysis, through design purposes up to a reference code for a real plant simulator.

The model of the pressurized water reactor loop that is under development initially originated from just a steam generator model. Initially just heat exchange was modelled. A model of the pressurizer was subsequently added with logic to control the level in the secondary side of the steam generator as well as the level of the pressurizer. For the conditions of the system at that time it was required to change the model from open (inlet and outlet) to closed (coolant flowing in a loop).

Final model consists of a Core (with Upper and lower plena), cold and hot lets, a steam generator (which is comprised of a steam dome and downcomer). Both sides – primary and secondary – are connected via a heat exchanger.

Author:  Michał Spirzewski