FAFNER is code developed by Lister which simulates by Monte Carlo methods the Neutral Beam Injection (NBI) technology, one of the most extended heating methods for fusion devices. To the date, FAFNER has been usually run at CIEMAT adapted to the TJ-II helical axis stellarator on shared memory Cray architecture machines. From this version, FAFNER has been ported to the Grid in the framework of the EGEE Project. At the same time, this work is the first step of a more ambitious target since the code can be now coupled to many others such as ion transport tools. In this paper, all these preliminary advances are described as well as the performance and portability gains obtained.