The Department of Defense and the National Nuclear Security Administration had to wait more than a year to refurbish aging nuclear warheads — partly because they had forgotten how to make a crucial component, a government report states.

Regarding a classified material codenamed "Fogbank," a Government Accountability Office report released this month states that "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."

So the effort to refurbish and upgrade W76 warheads, which top the U.S. Navy's (and the British Royal Navy's) submarine-launched Trident missiles, had to be put on hold while experts scoured old records and finally figured out how to manufacture the stuff once again.

According to the Sunday Herald of Glasgow, Scotland, Fogbank is "thought by some weapons experts to be a foam used between the fission and fusion stages of a thermonuclear [hydrogen] bomb."

The National Nuclear Security Administration is a semi-autonomous agency within the Department of Energy. It is responsible for the manufacture and upkeep of the nation's nuclear weapons.

A new facility was built at the Y-12 National Security Complex near Oak Ridge, Tenn., to begin production of Fogbank once again, but was delayed by poor planning, cost overruns and an failed effort to find an alternative to Fogbank.

"The Navy originally planned to start replacing old W76 warheads with refurbished ones on submarines in April 2008," states the GAO report. "However, owing to W76 production delays, the Navy had to replace aging parts of W76 warheads in its current arsenal and has had to delay replacing old warheads with newly refurbished weapons until April 2009."

The first refurbished W76 warhead was delivered to the U.S. Navy last month, according to an NNSA press release.

• Click here for the GAO report (pdf).

• Click here for the report in the Glasgow Sunday Herald.

• Click here for an article in the Knoxville News Sentinel, which has been following the story for months.

• Click here for the NNSA press release announcing successful delivery of a refurbished W76 warhead.