Hugh Pickens writes "The US and the UK are trying to refurbish the aging W76 warheads that tip Trident missiles to prolong their life and ensure they are safe and reliable but plans have been put on hold because US scientists have forgotten how to manufacture a mysterious but very hazardous component of the warhead codenamed Fogbank. 'NNSA had lost knowledge of how to manufacture the material because it had kept few records of the process when the material was made in the 1980s, and almost all staff with expertise on production had retired or left the agency,' says the report by a US congressional committee. Fogbank is thought by some weapons experts to be a foam used between the fission and fusion stages of the thermonuclear bomb on the Trident Missile and US officials say that manufacturing Fogbank requires a solvent cleaning agent which is 'extremely flammable' and 'explosive,' and that the process involves dealing with 'toxic materials' hazardous to workers. 'This is like James Bond destroying his instructions as soon as he has read them,' says John Ainslie, the co-ordinator of the Scottish Campaign for Nuclear Disarmament, adding that 'perhaps the plans for making Fogbank were so secret that no copies were kept.' Thomas D'Agostino, administrator or the US National Nuclear Security Administration, told a congressional committee that the administration was spending 'a lot of money' trying to make 'Fogbank' at Y-12, but 'we're not out of the woods yet.'"