New trends in space market require miniaturization of equipment, new embedded functionalities, a new design and production process and strong competitiveness. Electronic Commercial-off-the-Shelf (COTS) component such as System-On-Chip (SoC) are key enablers for high processing with wide flexibility, but they remain sensitive to cosmic radiations as they are not physically hardened. Therefore, a fine analysis is necessary to find the good compromise between protection, mitigation, redundancy and mission availability. We limit the study to SEE sensitivity analysis. The analysis will be fast and flexible, to enable early design evaluation with calculation of mission availability at functional chain level and then merged at system level. Model-based methods will help system engineers understand the FDIR measures and evaluate the mitigation mechanism in relation to their efficiency, cost and benefits to satellite mission availability. The method will allow analyzing the white box SoC subsystem, to identify, detect and mitigate failures of hardware part and to analyze the impacts on the functional chain. The results will then be merged at the system level to follow a classic black box analysis. A trade-off analysis will be performed by evaluating the cost of integration to compare the impact of mitigation on availability against its cost. The method will be built with the Capella system engineering tool environment. A viewpoint for availability assessment will be designed. It will allow modelling non-functional FDIR element and mitigation mechanism, capturing parameters necessary calculating availability in a non-intrusive way on the functional architecture deployed on the physical architecture. Special attention will be devoted to check whether this viewpoint can be shared/split with other safety analysis. The final system availability carried out under static analysis conditions will be integrated into Capella, assisted with graphical support for trade-off analysis.