The nuclear bomb convoys that regularly trundle through Scotland have suffered 67 safety incidents over the last seven years, sparking fears of a "catastrophic" accident.
Lists obtained by the Sunday Herald from the Ministry of Defence (MoD) reveal details of dozens of mechanical faults and equipment failures since 2000, as well as delays and diversions caused by anti-nuclear protests.
The incidents include numerous fuel leaks, a series of broken valves and several instances of engine and brake overheating. In October 2003, an axle began smoking due to "excessive use of wheel brakes" coming down a steep hill.
In February 2003 a bomb carrier's clutch "became inoperative", and in January 2005 a fuse box started smoking when a heated windscreen was turned on. There were also several tyre punctures and false alarms.
Altogether the MoD listed exactly 50 "engineering incidents to nuclear convoy vehicles" between 1 January 2000 and 30 June 2007. A second list disclosed 17 "operational incidents" over the same period.
Nine of the operational incidents involved delays or diversions due to the anti-nuclear demonstrations that have dogged the convoys for years. In July 2004, for example, the convoy was delayed 16 minutes by a protest at Balloch on Loch Lomond.
On other occasions the convoy was delayed because of other road traffic accidents. In March 2005 there was a "vehicle fire on hard shoulder", and in July 2004 a major accident on the opposite carriageway caused a 39-minute delay.
The lists were released by the MoD under freedom of information legislation, but usually don't specify where in the UK the incidents took place. According to the MoD, "minor unplanned events" and "trivial technical incidents" have been omitted.
Convoys of warheads for Trident missiles travel by road up to six times a year between the Atomic Weapons Establishment in Berkshire and the Royal Naval Armaments Depot at Coulport on Loch Long, north west of Glasgow. Often involving ten or more vehicles, they have been driven through 21 local authorities in Scotland.
David Mackenzie, a spokesman for Nukewatch which monitors the convoys, accused the government of putting people's lives at risk. "Transporting plutonium and high explosive in the same truck shows an incredible disregard for public safety," he said.
Protesters would "immediately disengage" if they were causing a risk, he argued. But he warned that protests were likely to increase because of growing public outrage about the convoys.
An accident could have "catastrophic consequences", according to John Ainslie, the coordinator of the Scottish Campaign for Nuclear Disarmament. "These latest disclosures reveal that there have been an alarming number of incidents involving the transport of weapons of mass destruction across Britain."
Ainslie argued that a recent emergency exercise imagining a major reactor accident at the Faslane nuclear base on the Clyde highlighted the difficulties of dealing with a disaster. The MoD has just released an official post-mortem (pdf) of the exercise last November, code-named Short Sermon.
It reveals manifold problems in responding to the accident, which envisaged radiation leaking out and contaminating the local area. Many of the government agencies which took part raised concerns about poor communications and inadequate office facilities.
"When you miss a "not" or similar you can get completely the wrong message," complained the Scottish Environment Protection Agency. "In a real event with no doubt more heat and nerves it would be difficult to think straight."
The MoD pointed out that the purpose of emergency exercises was to help improve preparations for "highly unlikely" accidents. "We learn valuable lessons," said an MoD spokeswoman.
She insisted that the 67 incidents had not been serious security failures. They were "low-key mechanical issues that in all cases have been resolved quickly," she said. "Safety and security is paramount to the movement of nuclear convoys and is not compromised at any point due to the stringent measures in place."
Further new evidence of the risks of nuclear weapons is due to be broadcast by BBC Radio Four tomorrow evening. A programme will reveal top secret documents from UK government scientists warning that up to ten million people in the south of England could have been put at risk by the stationing of US cruise missiles at Greenham Common in the 1980s.
Read an earlier story about the risk of nuclear warheads exploding in a crash here.