The blockage of a cooling loops by molluscs, caused a pneumatic vent valve to open on the temperature control system of an ammonia storage unit. At least 100 kg of ammonia was released into the atmosphere. At the same time, an individual located approximately 1,000 m away reported smelling ammonia. There remains, however, a doubt as to the connection between this perception and the release of ammonia. The accident had no consequence on the environment and claimed no victims.