Electrical cables are one of the main fire hazards in many industrial sectors such as buildings, aircraft, spacecraft, and nuclear power plants (NPPs). To assess the potential damages of the cable fires on safety-related equipment, fire safety analyses rely on tools that intend to determine the fire spread over multiple cable tray installations and the resulting heat release rate (HRR). The Fire Test Laboratory of the French Institute for Radiation Protection and Nuclear Safety (IRSN), in partnership with the Polymers Composites and Hybrids Department of IMT Mines Ales, has started an experimental research for more than 5 years on the study of cable ignition and cable flame propagation. These experimental studies were conducted with the CISCCO test device that allows to impose controlled heat flux on the combustible surfaces to simulate the preheating of the fuel material, the ignition and flame propagation. The implemented measurements such as fuel temperature, flame heat flux, flame spread velocity, were suitable to propose simple flame spread models on polyvinyl chloride (PVC)-based and halogen free flame retardant (HFFR) cables, that are two common electrical cable types used in NPPs.

To go further on the comprehension and the validation of pyrolysis and flame spread models, the fire community agrees on the need for perfectly instrumented analytical experiments. To the best of our knowledge, the potential of such experimental tests in the field of pyrolysis and flame propagation has remained largely unexplored to date, and the project aims at filling this science knowledge gap. For this purpose a simple combustible material in terms of composition and geometry will be defined and used instead of the complex geometry presented by the cable layer and used in previous studies. The study will focus on panels of homogeneous composition but representative of the outer sheaths of electrical PVC or HFFR cables. An initial theoretical approach will be carried out on a well-known academic fuel such as black PMMA, to conduct an exhaustive assessment of the metrology and of the experimental protocol. The second major objective of this research project is to develop and implement a metrology system that will ultimately evaluate or determine the main parameters used in current models of pyrolysis or flame propagation on surfaces. For example, the mass loss rate will be measured, and fine thermocouples will be inserted into the material to accurately estimate thermal wave propagation within the material. Infrared imaging will also be used to quantify in detail the temperature of preheating zones, a key parameter in propagation models. Finally, analytical pyrolysis models will be compared with experimental results, and model parameters will be clearly discussed and analyzed. A correlative approach may also be carried out in parallel, since it is of considerable interest for the validation of simplified pyrolysis models. In the longer term, the database will serve the fire research community both analytically and in terms of numerical simulations. These experiments may be used as reference experiments for international benchmarks.

PhD in fire science, experience in the conduct of fire experiments and solid knowledge of the related metrology, self-motivation, scientific rigor, work autonomy, ability to work as part of a team, English language proficiency, good writing skills and experiences with writing academic articles are highly beneficial