Harnessing energy by nuclear fusion has progressed into technological developments as a result of sufficient progress made in the theoretical investigations. Fueling a tokamak by pellet injection is reported to be most efficient among other fueling techniques. It is thus important to produce a solid hydrogen filament by extrusion process using an extruder-die setup. It is required to arrive at an optimum configuration of the die as the pressure drop in the die decides the load on the extruder. The present analysis focuses on developing a CFD model of a die taking into account the complex rheological behavior of solid hydrogen. A systematic parametric analysis is performed to study the influence of die geometry on the flow behavior. The un-yielded regions are identified from the simulation results. It has been found that the un-yielded region decreases as the contraction ratio and contraction angle is decreased. The un-yielded zone is predominantly present in the region before contraction. However, at lower flow rates, the un-yielded zone appears even after the contraction. © Published under licence by IOP Publishing Ltd.