FLIGHTS loaded with weapons-grade uranium that are being launched from a Highland airport are in dangerous breach of runway safety limits, according to documents released under Freedom of Information (FoI) law.

The revelations have led to angry accusations from politicians and environmental groups that a "horrific gamble" is being taken on these flights and calls for the nuclear transports to be banned immediately.

Bombs-grade uranium from Dounreay nuclear plant in Caithness is being flown from Wick John O’Groats Airport to America aboard 130-tonne C-17 US Air Force planes, which according to the documents, are too heavy for most of the runway.

The company that runs the airport denies these accusations and says the runway complies with current industry standards.

A deal to fly 700 kilograms of highly-enriched uranium waste from Dounreay to the US was announced by former UK Prime Minister, David Cameron, at a nuclear security summit in Washington DC in March. The first flight took place from Wick airport under armed guard on September 17 – and more are expected next year.

There were earlier reports that Wick’s runway was too short for C-17 aircraft and that the airport’s rescue and firefighting capability was inadequate. The flight from the US in September landed at RAF Lossiemouth in Moray, which experts say could have been to minimise the weight of fuel it was carrying for its short hop to and from Wick.

Now detailed technical reports obtained by the Sunday Herald disclose that the runway may not be strong enough to withstand the flights. Highlands and Islands Airports Limited (HIAL) had commissioned the US engineering firm AECOM to examine the structural suitability of Wick’s runway for C-17s, and it produced a 46-page report in October 2015.

Under safety standards used by the Ministry of Defence (MoD), the report found that most of the runway was deficient. “The movements of the C-17 will not meet the necessary criteria for normal overloading operations as stated in the guidance and thus should only be allowed in emergency situations,” it said.

Using safety standards from the civil airport company BAA, the report concluded “cracking of the asphalt material is to be expected under the overload operations”. It added that this should not lead to “failure” or “permanent deformation” of the runway, but inspection and maintenance after every C-17 flight was recommended.

The AECOM report led to a publicly-financed £9 million programme to resurface some of the runway between April and August this year. But although edges and ends were upgraded, documents released under FoI reveal that most of the runway was not upgraded.

The 33 plans, maps and reports released by HIAL, and by the UK Government’s Nuclear Decommissioning Authority (NDA) under FoI, show that the middle 1,390 metres of the 1,825 metre-long runway at Wick were not included in the upgrade.

Opposition politicians are planning to raise the disclosures in Westminster and Holyrood. Paul Monaghan, the SNP MP for Caithness, Sutherland and Easter Ross, highlighted previous concerns that Wick’s runway was too short and the airport’s rescue and fire-fighting rating was too low for the C-17 flights.

“We now know from these documents released by HIAL that the US company AECOM has estimated that there are significant deficiencies in the structure and surface of the runway at Wick, which is not considered sufficient for the safe operation of these aircraft,” he said.

“The NDA and the UK government are using Wick John O’Groats airport in circumstances that are completely inappropriate and highly unsafe. I have written again to the UK government asking why these uranium movements are necessary, and why safety is being compromised.”

John Finnie MSP, transport spokesperson for the Scottish Greens, called for the flights to be suspended pending a safety review. “The public will rightly be alarmed by this disclosure,” he said.

“It clearly suggests that no legitimate risk assessment has been undertaken and a lower standard is being applied simply because of what the cargo is. I intend raising this matter in the Scottish Parliament.”

Friends of the Earth Scotland described the released documents as damning. “It is almost beyond belief that these flights are using a runway that is not fit for purpose,” said the environmental group’s director, Dr Richard Dixon.

“Gambling against the horrific consequences of one of these flights crashing is bad enough but vastly increasing the risk of a crash by using an unsuitable airport is almost too stupid to believe. Whoever thought this was an acceptable plan should lose their job and these flights should be banned immediately.”

Tor Justad, chairperson of the campaign group Highlands Against Nuclear Transport, demanded an “absolute assurance” that the C-17 aircraft would not damage the runway or suffer an accident. “Safety standards are being compromised to allow the uranium flights to go ahead,” he said.

HIAL did not directly answer questions about Wick’s runway breaching MoD standards or being expected to crack. “The runway at Wick complies with current industry standards and specific areas were strengthened in late summer 2016 specifically to accommodate a limited number of movements by large aircraft such as the C-17,” said a HIAL spokesman.

“Inspections are regularly carried out in accordance with normal airport operating procedures. No damage has been found. HIAL has no comment on specific aircraft movements.”

HIAL stressed that it had “every confidence” in the structural integrity of the runway. “Safety has not been compromised in any way,” added the spokesman. “All permitted movements at Wick John O'Groats Airport comply with the operating protocols and requirements of the airport.”

The NDA confirmed it had commissioned a report into the suitability of Wick airport for the nuclear flights that had identified the need for improvements. “These improvements were carried out successfully, and the airport now meets the required criteria for safe and secure transportation of nuclear material,” said an NDA spokesman.

“The removal of nuclear material from Dounreay is ongoing, and it is the priority at all times to comply with regulations governing safety and security. This includes protecting information about ongoing operational activities.”