Within Framatome DTIPLN-F team, MCNP 5 is used over a large spectrum of application in radiation protection, particularly in cases where statistical convergence is challenging. ADVANTG (code using the CADIS method) is used for speeding up the calculations. MCNP 6.2 offers a new feature to describe geometries via unstructured meshes. This new pathway could simplify the work consisting of preparating the MCNP geometry decks, but the use of ADVANTG on such geometries is currently impossible. By subscribing to R&D efforts to improve calculation tools within the team, the mission consisted in the development of a Python library: RPTK, allowing in particular the use of ADVANTG as a technique for reducing the variance on MCNP 6.2 calculation models using unstructured meshes.