Britain's nuclear bomb factory has been struggling to remedy as many as 1,000 safety defects uncovered by the government's official watchdog. And it has only been allowed to remain open because the Ministry of Defence says the work it does is vital.
The remarkable and, until now, secret story of the serious problems being faced by the nuclear weapons complex at Burghfield in Berkshire is revealed in 13 internal reports released by the Nuclear Installations Inspectorate (NII) to New Scientist under freedom of information law.
For the last five years the NII has been trying to force Burghfield's operator, the Atomic Weapons Establishment (AWE), to tackle 1,000 "shortfalls" identified in its safety procedures. But an inspection in April this year found that more than 300 of them were still outstanding, New Scientist reports today - and they weren't due to be completed until after a deadline set for 27 September.
The NII has criticised AWE's progress as "poor" and "unacceptably slow", and warned that the only real solution is to start again from scratch. "The current facilities fail to meet modern standards," said an NII assessment in 2006. "Only the design, construction and operation of new facilities will ensure that modern safety standards are met."
Burghfield is home to some of the most dangerous and least known plants in the business of maintaining the UK Trident nuclear weapons programme. Bizarrely, they are officially known as Gravel Gerties, after a minor character in Dick Tracy comics from the 1950s.
In circular cells encased in thick concrete and buried under nearly seven metres of gravel, technicians take apart old nuclear warheads and then put them back together again to check that they are still functional. Great care has to be taken not to accidentally detonate the conventional high explosives that are packed around the plutonium core.
Should an explosion occur, the roof is designed to collapse and allow the gravel to pour in and prevent particles of plutonium from being blasted into the air. There has been concern in the US, which has Gravel Gerties at the BWXT Pantex plant near Amarillo, Texas and on the Nevada Test Site near Las Vegas, about the risk of plutonium leaking out if an explosion fails to lift the roof.
In the UK, the NII asked AWE to improve the safety of the Gravel Gerties in 2002, five years after it was first given legal powers to regulate them. A detailed review subsequently uncovered a very long list of "shortfalls" that the NII said needed rectifying.
Few details of the problems are given in the documents released to New Scientist, but it's apparent that a substantial proportion of them were defined as "category 1", the most serious level. They included potential deficiencies in concrete, bricks, filters, glove boxes and door seals, as well as in the ability of roofs and masonry to withstand earthquakes.
The AWE's programme to address the shortfalls was initially due to be completed by April 2006, but it was postponed to April 2007, and then again to the end of September. "Very limited remedial work has been undertaken to date," the NII reported in August 2006.
An inspection by the NII in April this year discovered evidence that some of the "engineering fixes" which AWE claimed to have delivered had not actually worked. This, the NII said, "does not instil confidence that AWE's own procedures are being followed."
In May NII wrote to AWE listing 46 specific problems with hoists, fire dampers, gas cylinders, cables, valves and other equipment that were not scheduled to be resolved before the September deadline. Without "robust" arguments justifying the delays, the NII would consider imposing "some form of operational restriction", the letter warned.
Some unspecified operations at Burghfield have been temporarily halted by the NII. But it has permitted bombs to carry on being dismantled and reassembled in the Gravel Gerties because of the Ministry of Defence's insistence that the work is "necessary in support of the UK Strategic Deterrent".
According to the NII's 2006 safety assessment, the number and nature of the shortfalls would "normally" have caused operations to be suspended. But, it added: "The true benefits from such ongoing operations can only be fully assessed by the MoD and can only therefore be fully evaluated by it."
Anti-nuclear campaigners claim that public safety has been compromised. "The NII has been effective in warning of the unsuitable state of the buildings and the poor working practices at Burghfield, but it is powerless to override the MoD," said Di McDonald from the Nuclear Information Service in Southampton.
There was an "inherent contradiction", she argued. "AWE are tasked with fitting a high explosive into a nuclear device that will work. But the NII's job would normally require them to ensure that such components are kept a safe distance apart."
This week, however, the NII maintained that "appropriate progress" was being made at Burghfield, despite the "limited" resources available to AWE. "If NII believed a particular operation were unsafe, it would not allow it to take place," a spokesman told New Scientist.
AWE denied that safety had been compromised, and argued that Burghfield met the NII's "stringent" standards. "The documents released by the NII demonstrate the comprehensive and robust nature of the regulatory process for AWE Burghfield," said a spokesman. "Such exchanges are to be expected in any such relationship - that is what external regulation is for."
The documents on which this story is based are all available here.
Read more stories about nuclear weapons here.