Spatzimaus
Mad Scientist
Check each AI city each round if there is some a-bomb order running, and if you find one replace it with something you think is more adequate in that situation.
That's a horrible way to do things. Artificially forcing the player to change its mind on things it's partially produced already (and has therefore already sunk hammers into) is incredibly unbalancing.
Besides, it does nothing to address the real problem. It's not the PRODUCTION of nukes that's the issue, it's the USE.
Right now, nukes are used on turn one of any war in that era, because there's currently no reason not to use them. Causing the AI to produce fewer nukes, either through build queue manipulation, flavor values, or resource limitation, would do nothing to address this; the AI would shoot off whatever nukes it had on Day One and be done with it.
To fix this, then, we need to add a consequence to using nukes (difficult at best in Lua, given the lack of relation stubs) and get the AI to understand that there are times when using a nuke isn't appropriate (impossible with the current mechanisms). No amount of flavor tweaking will substitute for this.