Special Nuclear Material flights between the UK and US

The UK has always claimed to have an ‘independent nuclear deterrent’. However for almost forty years Britain and the United States have been transferring copious amounts of technical information, materials and components for use in each other’s nuclear weapons programmes.

This co-operation has taken place under a number of different agreements including the 1958 US/UK Mutual Defence Agreement (last amended in 1994), the 1963 Polaris Sales Agreement and the 1980 Trident Sales Agreement.

One way in which transfers of nuclear materials and technology are carried out between Britain and the US is through special flights into and out of RAF Brize Norton in Oxfordshire.

Nuclear materials are flown backwards and forwards from the US on a regular basis in an RAF VC-10. At the U.S. end the planes land at Dover Air Force Base in Delaware, New York State.

The aircraft has to land at Dover because the US Nuclear Regulatory Commission will not allow air transport of nuclear materials within the US in containers that have not been licensed by them. US law demands that in order to get an NRC license any such container has to be so strong that it "will not rupture under crash and blast-testing equivalent to the crash and explosion of a high-flying aircraft". The IAEA tests which these containers are subjected to cannot meet this criteria.

The onward destination by land of these cargoes is unknown, but it is highly likely to be New Mexico or California where the US nuclear weapons research and development centres of Los Alamos, Sandia and Lawrence Livermore National Laboratory are based.

Between 1 January 1993 and 22 August 1999 there have been 15 flights into Britain and 32 flights out of Britain to the United States.

According to the Ministry of Defence:

"I can confirm that the Ministry of Defence does transport special nuclear material by air to the United States under the provisions of the 1958 UK/US Agreement for Cooperation on the Uses of Atomic Energy for Mutual Defence Purposes...

I would like to reassure you that we would not transport SNM by air unless it was safe to do so. Such movements are kept to the minimum necessary to meet operational requirements. All movements of SNM are carried out in accordance with stringent safety regulations, and by specially trained and equipped personnel, and dedicated military air traffic controllers are assigned to monitor and control movements in UK air space. SNM is transported in specially selected, multi engined aircraft and in specialised containers that are tested against accident environments specified by the International Atomic Energy Agency [IAEA]..." [letter to CND member from Mrs S ryan, Directorate of Nuclear Policy, Ministry of Defence, 24 November 1997]

SNM convoys are used by the Atomic Weapons Establishment to transport key components and materials for use in British nuclear weapons. The principal materials transported in these convoys are plutonium and highly enriched uranium but any highly classified components or technology can potentially be transported.

Flight Paths

There are two routes used by the RAF Special Nuclear Materials Flights:

Route One: The plane flies in a straight line from Brize Norton out into the Atlantic, overflying the Cotswolds, they then overfly the northern edges of Bristol and Cardiff to reach the Bristol Channel and the Atlantic.

Route Two: The alternative route takes the plane further to the north where it overflies Cirencester, Chepstow and travels through South Wales, over the northern edge of Newport, Caerphilly, Port Talbot and Swansea.

The most popular route is shown in the map below as a dotted red line on the standadrd civil aviation air routing map.

Once the RAF Special Nuclear Material flight reaches the United States it lands at the first available military airbase, Dover Air Force Base in Delaware.

What nuclear materials are carried on these flights?

The exact nature of the cargo remains a closely guarded secret. The only information we have is that they contain special nuclear material and have come from or are destined for use in nuclear weapons because the material originates from or is destined for the Atomic Weapons Establishments at Burghfield or Aldermaston.

How dangerous are these flights?

No completely accurate assessment can be made of the level of risk presented to the people below the flight path until full disclosure is made on the type of radioactive material the flights are carrying and in what form the material is transported.

The containers used normally look like oil drums and are about around three foot high.

With no accurate information available on the types of container used it is impossible to make an assessment of how a container would survive the impact of a plane falling from over 10,000 feet.

Accotrding to the MoD they are subjected to the IAEA tests but these only ensure that the container can survive an impact at a speed of 30mph (13.2 meters per second) and a 30 minute/800 degree celcius fire - grossly inadequate for an high altitude/high velocity aircraft crash.This well below the design standards for an aircraft black box which is designed to survive an impact of 135 meters per second (ten times greater than the IAEA standard).

What is clear is that it is not wise to overfly large centres of population with any radioactive material, regardless of whether it is plutonium, uranium or any other radioactive or toxic substance.

Aircraft accidents do happen and given that aircraft crashes normally involve fire and the virtual destruction of the aircraft, the containers used are unlikely to survive completely. Any fire would be likely to scatter radioactivity over a very wide area.

Both plutonium and uranium are highly flammable materials. They easily burn if exposed to fire, creating a highly radioactive plume of smoke, which is easily ingested. Both materials are also highly carcinogenic. The smallest amount of plutonium released into atmosphere, if ingested, can cause genetic abnormalities, such as cancer, in later life.