This project involves developing a neutron source routine within the ASCOT framework to support both thermal and heating-driven sources in fusion plasmas. A custom Ascot Fusion Source Integrator (AFSI) module is implemented to compute volumetric neutron sources from kinetic profiles and NBI-generated fast ion distributions. The routine will be compatible with both tokamak and stellarator geometries and will work as input data for Monte Carlo codes such as Serpent2.