I've been formulating a Master Plan for an 'ideal' fortress base design, and contemplating how to do it properly. Along the way, I've addressed issues like how to organize industries for vertical colocation (to maximize efficiency) and my practice forts have shown me good ways to set up water reactors with lever-operated filling mechanisms that are proof against swimming building destroyers or the like, while also not requiring buckets to fill.
Now, I was looking at the wiki today, studying the tower reactor. I often find I need power in a couple of places in my fortress (millstone cluster on one floor, mist generator above the meeting hall on another, eventual construction of drowning traps on a third floor) and the tower reactor looks like a really keen way to move water around, combined with an abundance of connection points for power trains on any level where there's a demand.
...but I'm not sure I'm understanding the design completely, and given the device's complexity and the potential involvement of aqueous Fun, I want to make sure I've got the concept solid before I consider how it would fit into my fortress.
So. Looking at the design:
1) it appears to be nothing more than a vertical shaft bordering a pump stack whose only function is to move water from the bottom to the top, dumping it into the vertical shaft to recycle back to the bottom once more.
2) There's a floodgate on the lowest floor to cut off the water supply if the reactor needs to be shutdown (for whatever reason). I can adapt this to a fortification/floodgate/fortification combination to protect the floodgate and keep the lever-pull-fills-reactor design.
3) The design appears to be safe. If allowed to run once the floodgate is pulled shut, it should pump most of the remaining water up the stack, leaving puddles (or nothing) behind, or at worst, it would strand some water in one or more levels.
Which leads me to my questions:
1) Am I understanding the device correctly? Particularly with respect to point #3 - a device that strands water in my fort in a quantity great enough to completely flood out lower floors under construction (assuming a very tall reactor) is potentially a hazard, while my current decentralized reactors are sufficient for my power needs and also completely safe to use.
2) Aside from possibly being dwarfier than multiple, separate, self-contained water reactors, is there any real reason to build one of these? Power itself isn't really an issue - I can run more millstones off one set of 3 water reactors than I really will ever need, and organizing a basic self-filling water reactor seems easier than trying to engineer a pump stack with a power coupling. I can use a long shaft/gear assembly to move power over long distances on one floor, and since the dwarves never need to access the reactors once the "fill lever" is activated and the pumps manually primed, the device can run mostly unattended. Is there a hidden draw to this design I'm not seeing?
3) How extensible is the device later, once it's already been filled and operational? My current water reactors are easily and safely extensible - just build more of them - so a device that would replace them must also have this feature.