[failwhaleshark]

Gotchas, tools, jigs, and tricks of design, manufacturing, maintenance, and support, as well as the very rare materials, are the most crucial bits to guard.

IIRC, the manufacturing of a low-yield, simple fission device based on an old design isn't complicated; it's the fissile materials that are the show-stoppers, hence nonproliferation of centrifuges, dual-use components, and yellowcake/ore.

[KMnO4]

Reminds me of a factory tour I went on where a big fancy robot was assembling car parts. I was told not to take photos — not because the robot was secretive (and in fact the same one was used in several factories), but because the computer screen beside it showed details about the specific configuration of that robot. There were hundreds of different settings that could be tweaked and that was the competitive advantage.

[failwhaleshark]

Makes sense. I toured the Dell factory in Round Rock, and it was the same deal. I think all businesses attempt to limit information disclosure as a standard practice, even if there aren't obvious trade secrets, because there maybe unrecognized intelligence in them.