(78c) Lessons Learned from the Buncefield Fuel Depot Explosion

On December 11, 2005 a vapor cloud explosion occurred at the Buncefield fuel terminal located twenty-five miles northwest of London. Significant overpressure damage occurred to the facility, neighboring businesses, and homes. The resulting post explosion fire continued for almost four days, consuming fuel from over 20 tanks, and has been described as the largest peacetime fire in Europe. Such significant damage had not been anticipated in risk analyses performed by the facility operator. This paper describes our investigation of the incident and identifies contributing causes that allowed the incident to occur and contributed to its magnitude. Investigation determined that the incident was caused by the overflow of almost 300 m3 of premium unleaded petroleum from a tank for approximately 30 minutes resulting in formation of a large vapor cloud. As is typical in incidents of this magnitude, multiple simultaneous failures had to occur to cause the incident. Historical operating data is reviewed and demonstrates that there were multiple previous failures of tank level sensors and operators relied on tank level alarms rather than monitoring the progress of filling tanks. Elements of the tank design are described that contributed to the evaporation of fuel overflowing from the tank. Lessons learned from this incident are described that can be used to prevent or mitigate similar future incidents.