The International Fusion Materials Irradiation Facility (IFMIF) employs an accelerator-based source utilizing the deuteron-lithium stripping reaction (D-Li source) to irradiate materials. Its objective is to develop materials able to resist the conditions in the inner walls of a fusion reactor. High availability is a fundamental requirement to produce the fusion materials database that allows finding suitable materials for DEMO design on anticipated timeline. In order to fulfill the availability requirements, RAMI (Reliability, Availability, Maintainability and Inspectability) program have to be considered from the very beginning. This Master Thesis contributes to the RAMI program for the deuterons injector of the IFMIF accelerator facility. The analysis developed starts from the identification of critical failures that leads to a loss of availability through a FMEA (Failure Modes and Effect Analysis) process. Fault tree technique has been adopted to model the failure behavior in the injector by using the failure modes found in the FMEA. RiskSpectrum PSA© code has been used for the system availability quantification. The analysis highlights critical injector components, events and parameters that contribute to the unavailability. The main critical components are the coils power supplies and the turbomolecular pumps of the vacuum pumping system. The present report proposes design modifications, in order to increase the availability. Several design options are evaluated, such as redundancies and components locations. In addition, technologies under study such as permanent magnets or multilayer coils have been analyzed. Both are suitable to achieve the availability requirements. However they must be evaluated by the IFMIF project team as viable options, due to the iterative nature of the RAMI process.