Aggressive integrated circuit density increase and power supply scaling have propelled Single Event Effects to the forefront of reliability concerns in ground-based and space-bound electronic systems. This study focuses on modeling of Single Event physical phenomena. To enable performing reliability assessment, a complete simulation platform named Tool suIte for rAdiation Reliability Assessment (TIARA) has been developed that allows performing sensitivity prediction of different digital circuits (SRAM, Flip-Flops, etc.) in different radiation environments and at different operating conditions (power supply voltage, altitude, etc.) TIARA has been extensively validated with experimental data for space and terrestrial radiation environments using different test vehicles manufactured by STMicroelectronics. Finally, the platform has been used during rad-hard digital circuits design and to provide insights into radiation-induced upset mechanisms down to CMOS 20nm technological node.