How would you design a TL7+ bunker?

[HuManBing]

I'm setting a game in a bunker in Gabon (the closest country to coordinates 0,0) and I'm trying to come up with design ideas. The bunker needs to be able to last structurally for a few centuries in a post-nuclear war setting, so the Berlin Bunker's design from WWII probably won't cut it.

What designs are best suited? I'm taking some inspiration from the Cheyenne Mountain complex in Colorado, USA. This is almost a tunnel through a mountain, with a straight-line pair of exits so that the atmospheric force of a blast should go straight through and be dispersed on the other exit.

I'm also thinking of a vertical shaft down. This is a common design for mine shafts, so a Gabonese government might choose this design for cheapness (you don't have to do so much excavation if the mine shaft already exists, perhaps mined for you by a French or Chinese consortium). I'm less sure how this would deal with the issue of collecting water over the course of centuries. The vertical axis shaft could have horizontal levels branching off it to form layered rooms.

I'm also stumped about power sources. I'm not sure if it's feasible to house a nuclear reactor in these sorts of complexes. Or if it's possible to drill down far enough to tap geothermal energy. Solar and hydropower sources strike me as being too dependent on surface conditions to be reliable, especially given the assumption of surface impacts from nuclear weapons.

[Fred Brackin]

Originally Posted by HuManBing

I'm setting a game in a bunker in Gabon (the closest country to coordinates 0,0) and I'm trying to come up with design ideas. The bunker needs to be able to last structurally for a few centuries in a post-nuclear war setting,

I'm also stumped about power sources.

You should be stumped for power sources. I can't think of anything that should last for centuries. You're ruling out anything with moving parts. The closest I can come is an RTG. Those have no moving parts.

Generally RTGs are considered to decline 10% in output every 14 years. So one that was massively over the necessary capacity might still put out enough of a trickle a few centuries later.

The moving parts clause is a big problem even for things that were shut down and survivors might hope to re-start. Conventional reactor fuel would be hopeless centuries later also.

[HuManBing]

For a power source, I'm thinking the after-arrivers could jerry rig something together if nothing could conceivably last centuries of neglect.

Perhaps the forward-thinking Gabonese government even stored spare parts for rudimentary renewable energy sources if and when the overland situation calmed down enough for solar, wind, or water energy to be viable again?

Edit: I guess this then shifts the question of survivability from the energy systems, as assembled, to the disparate parts thereof, as disassembled. Could components last for centuries?

[Fred Brackin]

Originally Posted by HuManBing

Edit: I guess this then shifts the question of survivability from the energy systems, as assembled, to the disparate parts thereof, as disassembled. Could components last for centuries?

Yeah, packed in enough grease or similar material metal parts could last that long. Keeping liquid fuel that long could be a problem. For a jungle area like Gabon I'd start with wood-burning gear to bootstrap my way up to ethanol of some sort.

More generally, tightly sealed rooms filled with an inert atmosphere like nitrogen and insulated (as in buried) to keep the temperature down would keep non-volatile objects fairly well. It'd be a fairly extreme measure for someone who was only planning for a few years though.

[Anthony]

If you don't care about keeping the power running continually, it's probably easiest to just figure that the new occupants, whenever they arrive, will bring their own power sources.

In any case, no structure built at that tech level will survive hundreds of years in a jungle environment -- without maintenance, it will be covered and significantly collapsed by plant life. Basically, if you find a structure that has remained basically intact, without maintenance, for centuries, it's in a desert or semi-desert area, which as far as I can tell does not describe any part of Gabon (in fact, Gabon appears to be one of the worst places in the world to site such a structure).

[Fred Brackin]

Originally Posted by Anthony

In any case, no structure built at that tech level will survive hundreds of years in a jungle environment -- without maintenance, it will be covered and significantly collapsed by plant life.

Underground construction might address some of these (valid) concerns. The problem there is staying above the local water table.

Although even a significantly monumental (in the literal sense of the word) might do it. The step pyramids at Chichen Itza are still standing.

[Anthony]

Originally Posted by Fred Brackin

Underground construction might address some of these (valid) concerns. The problem there is staying above the local water table.

For an archeologist, the best outcome might be a building that got immediately flooded and filled with mud. However, if you want a building that's usable without massive effort, that's not so helpful.

Originally Posted by Fred Brackin

Although even a significantly monumental (in the literal sense of the word) might do it. The step pyramids at Chichen Itza are still standing.

But not really as a usable building.

[HuManBing]

Okay, these suggestions are workable.

The setting behind the question is for a far post-apocalypse campaign. The campaign's central premise is that life on Earth has largely recovered from the war and most of the radiation is gone. Before the nukes were launched, many major nations were able to seed orbits with prodigious numbers of cryosleep units containing various segments of society. The campaign is looking at a bunch of these that have fetched down, some 800 years post-war, near coordinates (0,0).

The Gabonese bunker itself does not need to feature much of the original founders' gear. I figure part of it could have collapsed, to allow a "dungeon crawl" portion of the game. Part of it could be inhabited... and indeed various levels of it could well have been populated then abandoned (several times over) in the centuries after the war.

The Bunker's current occupants are a group of former orbitals who have made Earthfall and congregated here. They have TL 8~9 weaponry and some tech from that era. The rest of the outside world is mostly around TL 4 with a few pockets of scavengers who have higher TLs, including other (hostile) former orbital groups.

So, I guess the story will require some of the Bunker to be furnished with trappings developed post-facto by the returning orbitals.

[dcarson]

Build it into a mountain and the lowest level is the drain for the rest of the complex. That is how the old silver mines in Colorado were done. The big silver strike they drove a tunnel lower than all the different mines in the mountain and all of them drilled down to it to allow the water to drain.

They could use that to power a low flow hydro system that generates 10s of kilowatts of power. Not a major industrial level of power but enough for a smal community. Parts for that could have been stockpiled to be setup when needed and those could last quite a while in storage.

[Jonas]

There was an excellent article in the old Pyramid Archives that addressed this very issue, sadly now its unavailable.