Fire modelling of a glove box for use in a two-zone fire model

Abstract

Accidental fires in nuclear fuel manufacturing and reprocessing plants can cause the glove box containment to rupture with a risk of dispersion of radioactive materials within the installation. Fire safety analyses require an assessment of the resulting radiological consequences to reinforce the appropriate prevention and protection measures in these installations. Since 2019, a research project named FIGARO aims at reducing the uncertainties related to the assessment of the airborne release fraction of plutonium involved in glove box fires. As part of this project, a semi-mechanistic model of glove box fire was developed and implemented in the two-zone code SYLVIA. Modelling glove box fires is a challenging task due to complex phenomena occurring in the glove box during its combustion. No theory has yet been put forward on how to model all aspects of the problem, even for simple, open atmosphere conditions. This model separates the combustion of the polycarbonate containment walls of the glove box from that of the biological protection panels, by modelling a glove box as a set of horizontal and vertical walls. A validation of this model was performed on two large-scale glove box fire tests carried out in a confined and mechanically ventilated enclosure (BAG_CSS experiments). Note that some parameters of the glove box model have been calibrated on the glove box qualification test carried out in an open atmosphere, under a calorimetric hood. Considering this preliminary calibration, the fire heat release rate is well reproduced by the model for both experiments.