Kurzfassung:
This thesis deals with the various developments that have taken place to improve and extend the use of CRASH, a 3D Monte Carlo Radiative transfer (RT) code. Our first step was to enable the use of nested, refined grids that allow high resolution RT simulations using realistic density fields obtained from an adaptive hydro code. Next, we have parallelised the code using MPI and studied its performance. Finally, we have looked at the feasibility of introducing adaptivity within the RT code.