Accidental fires in nuclear fuel processing plants may lead to the rupture of the glove boxes (GB) that are used as containment devices. To evaluate the resulting risk of plutonium oxide (PuO2 ) and uranium dioxide (UO2 ) dispersion fire safety analyses need to assess the mechanism involved in GB fires. However, the computational modelling of such GB fires remain at its very early stages and mostly relies on mechanistic (e.g., two-zone) rather than computational fluid dynamics models. Indeed, the latter is quite challenging even in open atmosphere conditions. The present work describes a new step in this direction. Reactive large-eddy simulations of the stage of peak heat release rate of an open atmosphere GB fire are carried out on the basis of a recently-developed multiple inlet flamelet modelling framework. The computation of this configuration requires the description of combustion of two distinct fuels, PMMA and Polycarbonate, as well as their mixtures. The multiple inlet flamelet modelling framework is expected to provide a suitable basis for their representation. Thus, a strained diffusion flamelet manifold is generated and tabulated in terms of a reduced number of control variables: a mixture fraction, a fuel dilution parameter, the scalar dissipation rate (SDR) at stoichiometry, and an enthalpy defect to account for energy loss. The objectives of this study are aimed at (i) gaining some insights into the applicability and potential of the multiple inlets flamelet modelling framework to describe such practical conditions relevant to fire development in nuclear power plants and (ii) identifying the key steps for its future development.