Okay, so it may not use a deuterium-tritium "zipper" as a neutron source (also known as an initiator). It may use polonium--and polonium-based initiators are only good for three weeks, which is an infeasibly tight timeline for an operation that requires covert smuggling of the initiator component.
Additionally, "suitcase nukes" are "fractional-crit" designs--i.e., they do not have a supercritical mass, even at maximum compression of the special nuclear material. (This is particularly true if the device uses a non-spherical shape for the critical mass, which raises its surface area relative to its volume. An example of a non-spherical critical mass would be some of the nuclear artillery shells made during the latter part of the Cold War--they used a cylinder of plutonium that was crushed in a linear implosion.) This means that neutrons generated from the fission of the special nuclear material are likely to escape from the critical mass Fractional-crit weapons require a lot of extra neutrons in the pit in order to work. This in turn means that the weapon needs boosting--direct injection of deuterium and tritium into the pit at the instant of detonation to generate a small fusion reaction.
You only need to buy it once -- right before you plan on using it.
Which, in turn, raises a whole new set of problems.
Al-Qaeda would have to obtain a lot of tritium--much more than the weapon itself requires (because tritium exfiltrates through almost any container wall--it's hydrogen, after all--and because some would decay to helium during a covert transit. They would need to be able to separate out any helium that accumulated during transit. They would have to have operatives in place who could service the weapon (i.e., place the tritium in the "zipper" and replace the tritium gas reservoir--and those aren't exactly the sorts of skills that are readily available out there).
One way or another, the weapon has to have some maintenance done on it--and that requires an infrastructure to do so (even if it's only once).
Tell me -- prior to 911, did al qaida have to buy and maintain a fleet of jet airliners, doing regular engine and airframe maintenance, up until the moment of the attack?
No, which is an excellent argument for al-Qaeda not actually having possession of nukes at this time.
A far more likely scenario involves the theft or other acquisition of a ready-for-issue nuclear weapon from a repair/maintenance facility on a short timeline prior to the intended detonation (much as al-Qaeda acquired their aircraft for 9/11 immediately after fueling and maintenance, and immediately prior to the attack).
I was thinking of a different substance, actually, but I didn't mention it because I did not feel like getting the kind of snotty replies that its mention inevitably evokes from the legions of armchair Einsteins who love to demonstrate the scope of their knowledge (and generally succeed). Sorry about that, I've a hard time resisting the urge to damn with faint praise when it avails itself.
Anyway, I realize that scads of Internet "experts" insist that there's less than nothing to it, but frankly -- and, call me what you will -- I find that I have more confidence in someone like Sam Cohen, "father of the neutron bomb", who most definitely does take this stuff seriously.
So, in short, no, I don't think that the issues with tritium are necessarily a show-stopper.
[skipping over a bunch of "conventional wisdom"]
Al-Qaeda would have to obtain a lot of tritium--much more than the weapon itself requires (because tritium exfiltrates through almost any container wall--it's hydrogen, after all
Sorry, I just don't buy that. I don't buy it, because I can buy it -- for maybe fifty bucks or so, for a set of Trijicon pistol sights. Seems like plain ol' glass will contain it for years.
Oops!
--and because some would decay to helium during a covert transit. They would need to be able to separate out any helium that accumulated during transit. They would have to have operatives in place who could service the weapon (i.e., place the tritium in the "zipper" and replace the tritium gas reservoir--and those aren't exactly the sorts of skills that are readily available out there).
You will pardon me for mentioning that this sounds like a pile of ridiculous tripe. You make it sound like a nuclear weapon is something as volatile as an ounce of dry ice, which must be used before you blink and it's gone.
There is plenty of time for an al-q POS to take a bit of Tritium -- properly contained and sealed by his friendly rogue ex-sov scumbag -- and then transport it through our sieve-like "border" to his waiting compadres.
There's a time and a place for "whistling past the graveyard", but... OK, sorry, I lied. There isn't a time or a place for it -- thus, this isn't the time or the place for it. So please don't insult our collective intelligence by painting a rube-goldberg picture of a situation so bloody impractical that it'd be a stretch to even consider our military being able to deal with such funky materials. I mean, a nuclear missile sub, spending months at sea -- and yet, having to return home to make a "run for the border" to load up on another five minutes worth of Tritium? LMAO! Puh-LEEZE! Go peddle that crap somewhere else, OK? No offense, nothing personal, but LOL! (When I read such desperate script-reading, I have to wonder if I've engaged one of those folks who "posts for a living", or, if it's merely someone on a personal quest, fixated on imposing his wishes for how he'd like it to be, by pushing his stuff on the forum via use of the typewritten counterpart to the "command voice." LOL on wheels!)
One way or another, the weapon has to have some maintenance done on it--and that requires an infrastructure to do so (even if it's only once).
Anything that a KGB operative can be trained to do, an al-q operative can be trained to do -- especially if he's got a former KGB operative in tow.
The rest of your stuff is such a poorly attempted effort at reframing the topic via a flop of a non sequitur that I won't embarrass you further by deconstructing it.
Do you want to explain to me how it will DECAY to a heavier element.