The Multi-purpose HYbrid Research Reactor for High-tech Applications, MYRRHA is being designed at SCK CEN since 1998. The MYRRHA programme aims at demonstrating the principle of the Accelerator Driven System (ADS), with the main objective to study the efficient transmutation of high-level nuclear waste, and at providing a flexible and multi-purpose irradiation facility. It features a pool type reactor with subcritical core fed by a linear accelerator to sustain the fission reactions via spallation. Lead-bismuth eutectic (LBE) is both the selected coolant and the spallation target material. The present study is carried out in support to the safety assessment of MYRRHA.