This project aims to quantify the neutron damage of the NBI components for several source concepts, and the possibility of reducing the damage, e.g. by reducing the NBI port size or optimizing the shielding design. Knowledge of neutron doses will aid the design of radiation sensitive components in the NBI sources, such as for example permanent magnets used in the extraction grids or high voltage insulators in the grid holder boxes. Geometry modifications have an impact on the transmission losses of the neutral beam, which will be calculated by in-house experts. The neutron transport and deposition will be studied with the Monte Carlo code MCNP. MCNP is the standard code for ITER nuclear analysis. It is well validated and benchmarked, and its capabilities are well suited for fusion applications. Neutron source data and baseline designs of the DEMO NBI beamline are available via contacts in the Power Plant Physics and Technology programme of EUROfusion. This Master’s thesis project will be embedded within a larger project: a conceptual system study that investigates multiple design choices for every beamline component, their mutual dependencies and the consequences for the systems performance and compatibility with the nuclear environment.