from The Guardian, 21 February 2011
The risk that planes will crash into nuclear plants and release potentially lethal clouds of radioactivity is significantly higher than official estimates, according to expert evidence to a public inquiry.
Studies submitted to the inquiry to expand Lydd airport in Kent, which began last week, cast doubt on assurances from the government’s Health and Safety Executive (HSE) that the dangers of accidental plane crashes are too small to worry about.
An analysis by an independent expert concludes that the method used by the HSE to calculate the likelihood of crashes is “flawed” and could underestimate the risk by 20%. And a previously secret report for the HSE accepts that a crash could trigger a “significant radiological release”.
Critics say that this is the first time that it has been officially admitted that plane crashes could cause a nuclear disaster, and raises questions about the safety of nuclear plants around the UK. The HSE, however, insists that the risks remain low and are “acceptable”.
London Ashford Airport, near the town of Lydd on Romney March in Kent, has applied to expand its runway by almost 300 metres so that it can accommodate big passenger jets. This could more than triple the annual number of take-offs and landings from 9,000 to 32,000 by 2014.
The airport is less than five kilometres from the Dungeness nuclear complex, which includes one operating power station and one being decommissioned. Objectors, co-ordinated by the Lydd Airport Action Group (LAAG), are concerned that the £25m expansion will increase the risk of crashes.
In evidence to the public inquiry for LAAG, David Pitfield, an aviation risk expert from Loughborough University, argues that the HSE ‘s estimates of crash risks are "derived from statistically insignificant and outdated information". Using more comprehensive and up-to-date data, he calculates that the number of aircraft crashes per million flights rises from 1.52 to 1.79.
The HSE’s model failed to take account of different risks at different airports, Pitfield said. “This is unreasonable and the newer approach is able to distinguish between airports on the basis of traffic, meteorological conditions and airport influences on the frequency of accident occurrence,” he told The Guardian.
A report on the risk of planes from an expanded Lydd airport crashing into nuclear reactors at Dungeness was written for the HSE by consultants, ESR Technology, in 2007. A censored copy, marked “restricted”, has been released to the nuclear expert, John Large, who is also giving evidence on behalf of LAAG at the public inquiry.
The report says that aircraft impact had “the potential to lead to significant radiological release”. A plane that skidded along the ground for hundreds of metres before it hit “critical targets” at Dungeness “has been identified as having the potential to increase the probability of an impact leading to a radiological release”, it adds.
According to Large, this is the first official admission that such a disastrous accident could happen. When combined with Pitfield’s conclusion that the HSE’s risk estimates were unreliable, it suggested that the HSE was guilty of “complacency”, he argued.
“The safety of all of the UK's seven advanced gas-cooled nuclear stations is cast into doubt,” Large said. “All of this uncertainty over a key nuclear safety issue surely demands that the HSE gives an account of itself at the inquiry.”
The HSE, however, has not objected to the expansion of Lydd airport. “We conducted an assessment of the increased risk of aircraft crash and commissioned specialist independent analysis,” said an HSE spokesman.
“This concluded there would be a modest increase in risk, which remains within the appropriate limits set out in the safety assessment principles used by the HSE Nuclear Directorate to inform its decisions on nuclear safety regulation.”
The HSE’s estimates of crash risks had been crosschecked by independent experts, the spokesman added. “This validation has satisfied HSE that it has no grounds on which to object to this planning application.”
The public inquiry at Shepway Civic Centre in Folkestone reopens on 22 February and is expected to last until mid-July. The airport expansion is being supported by Shepway District Council and local businesses, and opposed by environmental groups.
David Pitfield's summary proof of evidence to the Lydd public inquiry is available on John Large's website here.
The version of the 2007 report by ESR Technology released by the Health and Safety Executive is also available here (7.3MB pdf, and difficult to read in parts).
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