A series of explosions occurred on a Sunday afternoon inside a pyrotechnic facility, when only the guardian was onsite. He sounded the alarm.
The fire would have been ignited in warehouse D22 by the fall (most likely caused by rodents, whose presence had been noted in this depot) followed by the untimely triggering of firecracker igniters and flares. During several minutes, the fire spread to other igniters as well as to cardboards. After some time, the blaze reached the detonation fuses, which wound up exploding and forming a small crater (0.5 m diameter over a 0.25-m depth). The products dispersed by this low-intensity explosion in turn caught on fire (anti-hail rocket launchers and a Class 1.1F nitrate explosive): they partially detonated, also forming a crater, 1.6 m in diameter by 0.25 m deep. Some 20 seconds later, nitrate explosives plus other explosives containing trinitrotoluene / pentolite detonated by domino effect, forming yet another crater, this one 5.4 m in diameter with a depth of 1.5 m. Such a violent explosion, whose power was estimated at 1.77 tonnes of TNT, blew out the metal frame of building D22. The blast effect severely damaged both neighbouring warehouses (D13 and D19, separated from D22 by 60 m) and deformed the structure of the D19 building. Flying hot metal particles reached building D19, which had already lost its cladding, and triggered the powder stored inside along with the successive explosions of black powder crates. Depot D13 burned rather slowly, triggering an explosion of the signal flares. The combustion of smoke-producing substances released a thick black plume of smoke and formed a column that could be seen from Pamiers.
The explosion, felt up to 30 km away, also damaged the site’s workshops, storage depots and offices. After extinguishing the dry grass fire in order to protect the remaining facilities, fire-fighters were able to bring the blaze under control around 9 pm. The next day, the burned warehouses were quenched to avoid any renewed risk of explosion, and the damaged depots were covered with a tarp. Since the accident took place on a weekend, no casualties were involved. Property damage was extensive (3 warehouses completely destroyed, damaged cladding and roofs on the other depots, broken glass panes). The plates used for roofs or walls became detached like petals on a rose, while inside the buildings all machinery remained in its place.
The plant’s 145 employees were furloughed and resumed their posts at the beginning of August. The extent of property damage amounted to 14.6 M francs (equivalent of 2.22 M). The operator modified onsite storage conditions to avoid incompatibilities between substances while improving management controls on stored quantities (rated value). The operator also reviewed building construction techniques and protections against rodent intrusion. The reconstruction of destroyed installations had to be submitted for a new approval procedure.
Download the detailed report in .pdf format (66 Kb)
