Source:
LATA decadelong effort to refurbish thousands of aging nuclear warheads has run into serious technical problems that have forced delays and exacerbated concerns about the Energy Department's ability to maintain the nation's strategic deterrent.
The program involves a type of warhead known as the W76, which is used on the Navy's Trident missile system and makes up more than half of the deployed warheads in the U.S. stockpile.
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The delay in retrofitting the warheads appears to validate long-standing concerns about an erosion of technical expertise at the Energy Department, as Cold War-era scientists and engineers retire and take with them detailed knowledge about the bombs.
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"I don't know how this happened that we forgot how to make fogbank," Coyle said. "It should not have happened, but it did."
Read more:
http://www.latimes.com/news/nationworld/nation/la-na-broken-warheads29-2009may29,0,787677.story
To summarize, we have forgotten how to make and maintain nuclear stuff from the 70s and 80s.