Plans by the US and UK governments to prolong the life of Trident nuclear weapons have hit a serious snag because of a dangerous and mysterious ingredient codenamed Fogbank. As a result, politicians are likely to come under pressure to fund the design of new warheads instead.
Both countries want to refurbish the ageing W76 warheads at the tip of Trident missiles, to make them safer and more reliable. But now their programmes face delays due to manufacturing problems at the Y-12 National Security Complex at Oak Ridge in Tennessee. A new $50 million plant built to replace a facility that had been demolished has run into teething troubles, suggests a series of hints from the US National Nuclear Security Administration (NNSA), which runs Y-12.
In a bid to the US Congress for 2009 funding last month, the NNSA said that the plant's operators faced "a major technical challenge with the production of a critical material" for extending the life of the W76 warhead. It didn't spell out the exact nature of the difficulties.
However, early last year Thomas D'Agostino, the NNSA's administrator, told a congressional committee that the problematic substance is named Fogbank. The NNSA was spending "a lot of money" trying to make this "very complicated material" at Y-12, he said, "and we are not out of the woods yet".
Both the NNSA and the UK Ministry of Defence declined to speak to New Scientist about the function of Fogbank. However, D'Agostino provided a few clues in his evidence to Congress: he said it involved a solvent cleaning agent that was "extremely flammable" and "explosive". The problem involved "dealing with toxic materials - hazardous to our workforce - but it's required".
Nuclear weapons experts speculate that the substance is associated with a foam that fills the space between the fission and fusion sections of the W76 bomb. According to one former nuclear weapons engineer in the UK, X-rays from the initial fission explosion could turn this foam into super-heated plasma, which could help compress and then ignite the fusion fuel. Other sources suggest it somehow helps to even out the way the force from the fission explosion compresses the fusion fuel.
Hans Kristensen, a nuclear expert from the Federation of American Scientists in Washington DC, says that the problems at Y-12 could have "serious implications" for the US and UK Trident programmes. If the problems can't be solved, he predicts government nuclear scientists would argue that developing a replacement warhead had become a "national emergency".
John Ainslie, who has been researching Fogbank for the Scottish Campaign for Nuclear Disarmament in Glasgow, is concerned that officials at the US Department of Energy will use Fogbank's problems as an excuse to build new nuclear weapons. "Replacing Fogbank with an alternative material won't make nuclear weapons cheap or safe," he says.
John Ainslie's paper on Fogbank is available to download here (Word). This story was followed up by The Guardian, Wired, and Knoxnews. There is also an interesting and well-referenced blog on Fogbank at armscontrolwonk.com.