"Fogbank," the aerogel at the heart of this issue, is made with very toxic solvents. It would not surprise me that most of the documentation on the processes to make it were destroyed to avoid litigation over health and safety issues.
I remember when a physicist came to give a lecture at Cornell about the difficulties of cleaning up Hanford, Washington. It was a hair-raising presentation. I forget the details, but the gist is here:
Some physicist will correct me, but I think this is more of an accounting trick than a technological one: it serves to ask for more money.
I have no evidence, but my impression is, that aerogel is used to track the ageing of the decaying warheads, also providing data for the computed simulations to be more realistic. Such aerogel is readily available on the free (in the doublespeak sense) market.
The building it was originally made at in Y-12 (called facility 9404-11) was torn down in 2004. The nasty solvent (which metabolises in the body into cyanide) called acetonitrile, of which Wikipedia claims there is supposedly a world shortage as the sole remaining factory producing it was shut down in 2008 (to reduce pollution) for the Olympics.
This is so concerning on so many levels. The ineptitude and lack of accountability by the powers that be is borderline criminal.
In a separate vein I'm sure I'm not the only one to realize that people in the West, and in America in particular, have forgotten how to make things. Be it fogbank, tanks, textiles, semiconductors and soon to be cars. We keep farming out manufacturing to the lowest oversees bidders and soon enough all we know how to do is place orders.
What happens, god forbid, when our trading partners become our enemies and they withhold the materials which we need to fight them. How about the semiconductors used in critical systems are compromised by foreign actors? All we can do is hope people at the helm have already thought of this stuff and are doing things to mitigate the risk. I'm not too sure.
