Love it. One of maybe three so far I'd have a hard time picking between if we had to decide on our favorite.
The graphic design is very good. Maybe I don't super-duper love the colour scheme and maybe the NPC table is taking things a bit far in terms of tiny font size, but whatever. Minor nitpicks. It's clean, it's functional, the ordering of information makes sense, I had no trouble following the story and knowing where to refer back to when checking things.
Likewise, the writing is clear and to the point, and lets the material shine on its own terms without pretense. Just the way this news editor likes things.
Not even a criticism, more an observation: this kinda falls somewhere in between a setting and module. I like that you gave the Warden freedom to decide what the setup is, while also making suggestions. The only downside to that is that there isn't a built-in reason for the players to stay long on the lower levels and risk getting swallowed up. Obviously at the tail end of things you get caught between a literal rock and a hard (radiation) place, but in the middle stages there might be a slow period unless the Warden comes up with a reason to get the players to go back down for something.
For that reason, if I run this, I'll probably do at least two scenarios in the same setting and let the players get used to SUMU-7A in its normal state before it starts trying to swallow them whole. That way I can let the plot naturally give them a reason to stay near the bottom as long as they can, or try to go back to rescue someone, or whatever.