[Lael]

The half-life of the triggers for such atomic weapons is typically 60 days, after that, the weapon requires new radioactive material (as well as specialized electronincs maintenance)

Actually when the 'triggers' (the still classified Initiators) used Radio Isotopes to operate, that may have been true.

I understand from an article in the Economist that modern nuclear 'triggers' use a Vaccuum Tube to provide the requisite Neutrons.

The article did not disclose how it is constructed.

[Southack]

"I understand from an article in the Economist that modern nuclear 'triggers' use a Vaccuum Tube to provide the requisite Neutrons."

That would be quite a trick, having vaccum tubes splitting atoms in order to release their core neutrons instead of the electrons normally emitted by tubes, moreover, how do you get a fragile piece of glass to function inside of an exploding (the conventional first stage) bomb?