The nuclear warheads for the UK Trident system are assembled at Atomic Weapons Establishment (AWE) Burghfield near Reading. They are loaded onto the missiles which stay in the submarines at Royal Naval Armaments Depot (RNAD) Coulport on the Clyde.
Nuclear weapons convoys travel up to six times a year delivering warheads from Burghfield to Coulport and returning with others for refurbishment. These same vehicles also transport other military nuclear materials such as tritium and submarine reactor core rods. They also go on training runs and to other locations for accident exercises.
Vehicles
The convoy comprises about 20 vehicles which can be spread out on motorways but tend to close up together on smaller roads. The large 44 tonne load carriers are currently made by Mercedes (with their bonnet badges removed) and unlike most lorries on the road have seven axles. They are dark green and the trailers are covered in a tight canvas.
The convoy has a lot of escort vehicles with dark blue Mercedes armoured vans with Blue and yellow checks on either side at the front and back of the convoy and green Mercedes armoured vans behind each warhead carrier.
The convoy also travels with a red fire engine and a number of MOD and civilian police vehicles.
Following up some distance behind are the support vehicles; a huge workshop truck with a trailer, a tow truck, a spare tractor unit and a coach with the convoy crews gear.
Cargo
The Trident warheads are carried in large crates inside the green trucks. They are fully assembled and complete. The core of the warhead is a ball of plutonium and uranium. This is surrounded by specially developed conventional high explosives which would be ignited to create the critical mass necessary for a nuclear detonation when launched and targeted.
Destinations and routes
The components for the warheads are made at AWE Aldermaston in Berkshire and taken to nearby AWE Burghfield for assembly. The convoys take the completed warheads from Burghfield north to Coulport on Loch Long, north of Glasgow. At Loch Long the carriers are unloaded and the warheads placed in underground bunkers in the Trident area. When required they are taken to the Explosive Handling Jetty at Coulport where they are fitted onto the missiles on the Trident submarines. The warheads require to be checked every so often and batch samples are taken from the Coulport depot to Burghfield and returned to Coulport after servicing. In 2016 there were six convoys and Nukewatch believes that this was part of the warhead upgrade programme.
The MOD prefers convoys to travel on motorways and A roads but at either end of the route they must use smaller roads. Not all roads are passable due to the great weight of the convoy trucks. There is an eastern route, mainly relying on the A1(M), and a western route using the M6. Emergency exercises take place on bases in East Anglia and occasionally elsewhere such as Prestwick airport.
For more information and news of recent nuclear convoy movements visit nukewatch.org.uk
A number of Trident Ploughshares members are also active with Nukewatch helping to track these convoys. Also in 2017 David Mackenzie and Jane Tallents wrote a report, UNREADY SCOTLAND, calling on the Scottish Government to review the preparedness of the Scottish civil authorities to respond to a serious nuclear convoy incident.