During the morning of March 27, 1998, Toulouse residents woke up to the smell of ammonia across many districts of the city. The urea plant involved received numerous phone calls with complaints.
This Technical Paper (Part 1) explains why even large ammonia leaks can go unnoticed by the plant employees, also in case ammonia sensors are present. By making use of EFFECTS, Gexcon's state-of-the-art software suite for consequence modelling, simulations were conducted to reconstruct the above incident. Plus valuable insight has been gained in the influence of several parameters on the dimensions and lay out of toxic and irritating ammonia cloud contours. Our next Technical Paper (Part 2) will discuss the proposed prevention and mitigation safeguards.