SIMULATIONS of accidents involving nuclear weapons have revealed that the UK authorities were not fully prepared to protect people from being exposed to radioactivity, according to confidential reports obtained by New Scientist.
The revelations come in the wake of reports that the UK is considering replacing its existing generation of nuclear warheads, which are attached to submarine-launched Trident missiles.
Because the warheads need to be constantly refurbished, batches are shuttled by road convoy several times a year between the Atomic Weapons Establishment at Aldermaston in Berkshire and the Royal Naval Armament Depot at Coulport in Dumbartonshire.
The Ministry of Defence (MoD) regularly runs exercises to evaluate how the armed forces, emergency services and local authorities would respond to accidents en route. The exercises imagine crashes in which trucks carrying nuclear bombs burn, explode and scatter plutonium downwind.
In response to a request from New Scientist under the Freedom of Information Act, the MoD released post-mortems of four exercises conducted during the past decade (see "The road to disaster"). They reveal that delays in issuing public warnings, poor monitoring of radiation and breakdown in communication could all have increased people's exposure to radiation.
For instance, a 90-minute delay by the police in evacuating people from a contaminated area in the 2000 exercise resulted in radiation exposures to the public that were "very much higher than they would have been if action had been taken promptly", says a report by the MoD's Nuclear Accident Response Organisation.
And in a 1997 exercise, advice given to the public on evacuation was "erroneous" and there were deficiencies in monitoring the spread of contamination, slowing down the response to radiological emergencies, the report says.
Communications were often hampered by faulty equipment, inadequate facilities and confusion over the correct units of measurement for radiation. Overall, more than 40 aspects of the exercises were rated as "unsatisfactory" by the MoD.
These problems are "very disturbing", says Frank Barnaby, a nuclear consultant who used to work at Aldermaston. But the MoD points out that there has been no accident in which radioactivity has leaked from the UK's nuclear weapons. "Exercises are a powerful tool for verifying and improving the emergency response arrangements," says an MoD spokesman.
However, after the 1996 exercise, Aldermaston officials warned that a real accident might be much harder to deal with. "We are possibly misleading ourselves into believing that we can manage the very real logistical problems of an actual response," they said.
THE ROAD TO DISASTER
Code name: Senator 2001
Scenario: A nuclear weapons convoy is involved in a road accident.
What went wrong: The Ministry of Defence accuses the police of "ineffective control" and criticises the "weak" initial response of the civil authorities. A safety assessment of the nuclear warheads by the Atomic Weapons Establishment is four hours late.
Code name: Senator 2000
Scenario: A weapons truck smashes into a furniture van and a milk tanker.
What went wrong: The police experience "major frustration" because casualties are "poorly handled". The MoD takes only "piecemeal" account of new science when assessing radiation doses from plutonium.
Code name: Senator 1997
Scenario: A gas tanker crashes into a weapons truck, destroying two warheads and scattering plutonium downwind.
What went wrong: The public are given the wrong safety advice. There is "a lot of confusion" between civil authorities, and ambulance crews are not warned of the risks before attending to casualties.
Code name: Senator 1996
Scenario: The conventional explosives in two warheads detonate after a media helicopter falls onto a bomb convoy.
What went wrong: Safety advice on shelter and food is hampered by a "politically unacceptable" lack of data from radiation monitoring. The transport is "haphazard" and there are shortages of medical supplies.