This report describes récent results obtained at the French "Institut de Radioprotection et de Sûreté Nucléaire" on fire behavior in confined and mechanically ventilated compartments. Thèse fire scénarios are considérée as typical ones in the nuclear industry and are investigated at large scale with the final goal to comply with needs expressed for fire modeling and fire hazard expertise of IRSN. First, the large-scale facilities and the expérimental capabilities of the fire test laboratory of IRSN are reminded. They are composed of the unique multi-room DIVA facility and a large-scale calorimeter called SATURNE. An overview of the complète instrumentation set-up on thèse facilities is described. It mainly consists on up to date techniques commonly used in expérimental fire science. Then, the paper présents an overview of new results concerning four key topics: burning rate for under-ventilated fire, pressure variation of gas within a compartment, fïres of electrical cabinets and strategy of ventilation during fire scénarios. For each topic, data obtained from large scale tests are presented and the main results are discussed. This expérimental research performed at large scale provides new information that improves the physical understanding of fire scénarios in confined and mechanically ventilated compartments