What is being calculated with nuclear weapons? I understand it must have been computationally expensive to get them working, but once completed, what is there left to calculate?
I don't work in this area, but think about all of the variables that go into warhead maintenance. Your single supercomputer simulation can show that the warhead should work as-designed, but what will happen after the Plutonium pit has been sitting for a decade, slowly decaying? Will satisfactory implosion still happen if storage conditions slightly change the performance of the conventional explosives?
Since modern warheads are all fusion-type warheads, there's also the fusion stage to consider with even more highly classified top-secret sauce. It appears that the conditions for fusion are triggered by radiation pressure, and that likely makes things even more complicated. Now, you need not just a successful supercritical fission event, but one of the right shape(?), timing, and interaction with other secret-sauce materials that might have their own degradation curves.
So, rather than simulate one design, now you need to simulate hundreds to thousands to explore the full decay-over-time space. Getting the answer wrong means either very expensive premature warhead refurbishments or a nuclear stockpile that wouldn't work properly.
The original nuclear powers are accumulating really old atomic bombs / rockets.
We dont know for sure what is going on inside the warheads.
(or possibly a sub section of the war head)
Cracking them open to have a look may not be a good idea.
but leaving them alone for another few decades might not be wise either.
Funny fact: A lot of the nuclear weapons that have been destroyed, have
removed them from bombs or rockets.
But in many case the warheads were moved into storage.
Ready to slap them on a rocket if that should become needed.
>The original nuclear powers are accumulating really old atomic bombs / rocket
The US is replacing its nukes: the new nukes have all new parts except the fissile material. Russia is ahead of the US here and has finished replacing its Soviet-era nukes in this way up to the limit of what they are allowed to deploy under the START treaties. (I.e., they might have some Soviet-era nukes, but if so, they need to stay in storage for Russia to stay in compliance with its treaty obligations.)
US and Russia no longer explode nukes to make sure they still work, which is where simulations using supercomputers come in.
