Preliminary study of MYRRHA control system analysis

The main purpose of this Master Thesis consists in analyzing part of the control systems considered for the MYRRHA plant by the use of both graphical programming languages and system code calculations. Two paths have been initially undertaken in order to simulate MYRRHA reactor dynamics: the first one foresaw a very simple and schematic plant model simulated through lumped parameter balance equations in MATLAB – Simulink environment. This approach should have provided fast running transients and easy implementation of the controllers. The components requiring only single phase balance equations to be properly represented have been developed through differential energy balances implementation, while two-phase systems have required a different approach. The second way followed is instead characterized by a more detailed neutronic and thermal-hydraulic plant model in which computationally heavier (i. e. slower) calculations and less intuitive control system implementation were the prices to pay in order to obtain more accurate results. In fact, the thermal-hydraulics of such a complex plant required the implementation of a model capable to follow the non linearities of the system itself. This is the reason why the second part of the work was devoted to the development of a RELAP5-3D model of MYRRHA.