Pollution
Humain
Environnement
Economique

At 9 am, nitrous vapours were released in the surface treatment workshop of an airframe manufacturing plant. The chemical reaction started when a technician began transferring a spent bath containing 247 l of nitric acid and 25 l of fluorhydric acid into a 1 m³ plastic container. The employee stopped the pneumatic pumping and raised the alarm. A second technician wearing a mask and gloves resealed the tank and moved it outside the building. Noticing a rise in pressure in the container, he removed the bung; the exothermic reaction ended in the open air. The operator evacuated the staff from the area of the accident and then the 350 employees of the plant. The first technician was hospitalised for 3 hours for lung examinations. The mixing of the acid solution with a residual solvent present in the container caused the gaseous emissions. According to the operator, 1 to 2 l of solvent and 1 l of acid bath may have been mixed together. The investigation showed that the subcontractor who had supplied the empty packaging, had delivered a contaminated container which should have been destroyed. The handling error occurred during the holidays of the employee who was usually assigned to this operation. The investigation also revealed that there was no procedure for emptying the baths. The inspection authorities for classified facilities drew up a report establishing the facts and recommended that the Prefect issue a formal notification order. The accident did not result in any property damage; shutting down the establishment’s operations until 12:30 pm, however, resulted in losses estimated at €120,000.