Nuclear weapons materials have been flown between the UK and the US 23 times in the last five years, according to the Ministry of Defence (MoD).
Though the MoD doesn’t give details, the flights are believed to have carried tritium, plutonium and enriched uranium, all vital ingredients of Trident warheads. They probably started or ended at the Royal Air Force (RAF) base at Brize Norton in Oxfordshire.
The flights have alarmed politicians and campaign groups, who are worried about accidents causing widespread radioactive contamination. The MoD, however, insists that the transports complied with stringent safety rules.
The Ferret reported on 9 February that two MoD emergency exercises in 2011 and 2012 codenamed Astral Bend envisaged planes carrying nuclear materials crashing. One imagined a leak of enriched uranium and plutonium spreading up to five kilometres across south Wales.
That prompted questions about nuclear flights in the House of Commons. “In the last five years, 23 flights carrying defence nuclear materials were undertaken,” defence minister, Penny Mordaunt, told MPs.
“All flights were between the UK and the United States on fixed wing aircraft under the control of UK Armed Forces.” Details of the cargoes were kept secret “as disclosure would or would be likely to prejudice national security”, she said.
Experts say that the UK and the US regularly exchange tritium, plutonium and enriched uranium under a mutual defence agreement. Anti-nuclear campaigners have tracked road convoys transporting nuclear materials between the nuclear bomb plants at Aldermaston and Burghfield in Berkshire and RAF Brize Norton.
The independent nuclear engineer, John Large, argued that the MoD’s air shipments would not comply with international safety regulations for civil nuclear transports. A crash could “contaminate large tracts of land with potential radiological consequences for unprotected members of the public,” he said.
Tom Clements, who heads a group monitoring a nuclear weapons plant at Savannah River in South Carolina, claimed that the MoD flights would not meet US standards for civil nuclear shipments. The flights had “disturbing” implications for the world’s attempts to reduce the proliferation of nuclear weapons, he said.
Peter Burt from the UK Nuclear Information Service highlighted the high risks of air shipments. “The RAF regularly fly nuclear materials over large urban areas such as Bristol, Cardiff, and Swansea, which raises serious questions about what would happen in the event of an accident involving one of these flights,” he said.
It was the Scottish National Party’s defence spokesman, Brendan O’Hara MP, who asked the parliamentary questions about the flights. He described the MoD response as “alarming” and called on the ministry to explain its risk and safety assessments.
The MoD maintained that the air transports were safe. “The transport of defence nuclear materials is carried out to the highest standard in accordance with stringent safety regulations,” said an MoD spokeswoman.
“In over 50 years of transporting defence nuclear materials in the UK, there has never been an incident that has posed any radiation hazard to the public or to the environment.”
A version of this story also appeared in The Guardian on 29 February 2016.
Image of nuclear convoy entering RAF Brize Norton in June 2010 thanks to Nukewatch.
