The Institute for Plasma Research (IPR), India, is currently involved in the design and development of its Test Blanket Module (TBM) for testing in ITER (International Thermo nuclear Experimental Reactor). The Indian TBM concept is a Lead-Lithium cooled Ceramic Breeder (LLCB), which utilizes lead-lithium eutectic alloy (LLE) as tritium breeder, neutron multiplier and coolant. The first wall facing the plasma is cooled by helium gas. Thermal hydraulic safety analyses are being carried out with the system code RELAP/SCDAPSIM/MOD4.0 whic h was initially designed to predict the behaviour of light water reactor systems during normal and accident conditions. The code is being developed as part of the international SCDAP Development and Training Pr ogram (SDTP) coordinated by Innovative Systems Software (ISS). The modeling strategy of the RELAP code for the simulation of two-phase flows is based on a single-fluid two-phase approach with a set of momentum, energy and mass equations for each phase. The two phases are liquid-water and gas phase mixture of steam and non-condensable gases. Phase interactions, such as interphase friction and heat transfer, are modelled by closure relations based on experimental/numerical correlations that depend on the flow regime. In cooperation with ISS, the IPR team has implemented LLE liquid phase thermodynamic properties as a working fluid alternative to water and appropriate wall-to-LLE heat transfer correlations. However, in order to analyze some of the postulated off-normal events, there is a need to simulate the mixing of helium and Lead-Lithium fluids In the standard RELAP/SCDAPSIM/MOD4.0 ve rsion it is not possible to simulate a mixture of a non-water fluid with a non-condensable. In addition to that, t he available flow regime maps for vertical and horizontal flows in RELAP are specific for steam/water pair, which may not be suitable for LLE/helium pair. The Technical University of Catalonia is cooperating with IPR to adapt the RELAP/SCDAPSIM/MOD4.0 code to allow the si mulation of LLE and he mixture. This paper presents the results of the first step of the project, which includes a state of the art on simulation of liquid metals mixed with non-condensable using system codes, the implementation of the necessary code modifications to allow for a LLE/he mixture a nd preliminary results using the modified code version for horizontal and vertical configurations.