NEBOSH Practice Test

During the Buncefield incident, what caused the fuel explosion?

1. A lightning strike

2. Ignition from a nearby fire

3. Vapour cloud ignited at a pump house

4. A gas main explosion

The correct answer is: Vapour cloud ignited at a pump house

The Buncefield incident, which occurred in December 2005, was primarily attributed to the ignition of a vapor cloud that had formed due to fuel overfilling. During this incident, a significant amount of fuel was released, creating a vapour cloud that became highly concentrated in certain areas. When this vapour cloud reached an ignition source, it triggered a series of explosions. The ignition occurring at the pump house was a critical factor in this incident. The failure to properly manage the fuel transfer process led to an overflow situation, and the subsequent vapour formation created the hazardous conditions that culminated in the explosion. Understanding this mechanism is essential for industrial safety, as it emphasizes the importance of proper handling and containment of flammable substances to prevent vapor formation and potential ignition sources. The other options did not play a role in this specific incident. A lightning strike, nearby fire, or a gas main explosion were not examined as direct causes of the Buncefield disaster, reflecting the unique circumstances that contributed to its occurrence.