More study needed over Buncefield

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Experts examining the devastating effects of the Buncefield disaster say they cannot explain the massive forces the blast generated.

Buildings surrounding the fuel depot at Hemel Hempstead in Hertfordshire were damaged and cars thrown into the air by the explosion in December 2005.

But a panel of scientists say current theories cannot fully explain the power behind the explosion.

They are now seeking cash to carry out vital research into the incident.

Professor Dougal Drysdale, who brought the group of experts together, said: "Understanding the explosion further is a matter of international interest."

The Buncefield Major Incident Investigation Board (MIIB), which was set up by the government in the wake of the explosion, has published a report to outline the further work required.

Investigators already believe an apparently faulty gauge and safety devices led to the overfilling of a huge tank leading to an escape of unleaded petrol which became a cloud of flammable vapour that ignited.

It is important to carry out more work to understand the mechanism which caused the Buncefield explosion Professor Dougal Drysdale

What is not understood is why the vapour cloud burned at a much faster rate than expected and created pressures which led to the cars being blasted off the nearby car park and damage to buildings all around the oil depot.

Prof Drysdale said: "It will take some time, possibly several years, to complete the research necessary.

"The pressures created in the explosion were like a diver suddenly finding himself at 32 feet underwater - that's a high pressure to be at.

"We also expected the vapour to burn relatively slowly but combustion in the explosion was so rapid these high pressures were created and we want to know why."

'Sure of our facts'

The group needs £200,000 to continue its assessment of the explosion and to define the requirements for further research.

They believe their findings will help shape important safety measures which may be needed to prevent future explosions.

Professor Drysdale, from Edinburgh University, has brought together six experts one of whom worked on the inquiry into an explosion at a chemical plant at Flixborough in South Humberside in June 1974 when 28 people died.

Others are experts in combustion and explosions or representatives of the oil and gas industry.

Professor Drysdale said: "We want to be sure of our facts before making recommendations on the design of oil depots and this is why it is important to carry out more work to understand the mechanism which caused the Buncefield explosion."