A few weeks ago, I mentioned that James Sterngold at the San Francisco Chronicle revealed new studies that suggest plutonium ages rather well (much like Sophia Loren, I observed).
Sterngold is back with a longer article on the subject:
Although the results are preliminary, some scientists who have reviewed parts of the research say the fuel could be potent for a century or more, far longer than the 45- to 60-year minimum lifespan for the plutonium components—known as pits—previously estimated by the weapons labs.
[snip]
“I wouldn’t be surprised if 100 years is the new number,” said Raymond Jeanloz, a physics professor at UC Berkeley who has served as a government adviser and helps monitor research at the weapons labs.
“They’ve really agonized about every conceivable detail,” added Jeanloz, who is also chairman of the Committee on International Security and Arms Control at the National Academy of Sciences. “It’s been very hard to come to a consensus. But it looks like it could be years or decades or millennia before any serious degradation takes place.”