I’ll grant you that building a bunker would be fun. Extreme preppers, on the other hand, I don’t find fun, for the same reason that I don’t like hanging around with conspiracy theorists, closet racists, randroids, goldbugs, militia-men or PUAs. In fact, much of the time there’s a lot of cross-over among these groups, for reasons that I have suspicions about but have not been able to fully articulate.
Don’t get me wrong, I’m into survival skills (although I’m not as interested in guns as many survival hobbyists) but there are people that take that sort of interest to the point where it becomes a mental health concern - they’re not preparing systematically for a reasonable, foreseen event but rather responding irrationally to a vague and non-specific sense of fear that can be subdued by nesting in a pile of tinned goods.
Incidentally, I don’t think steel is that effective at EMP shielding - wouldn’t aluminium or copper be better?
As long as any of these are capable on focusing on the technical part, and agree to not go much into the ideological swamps where time goes to die and nothing useful comes back, even they are fairly easy to talk with.
If you are friendly with them, they may share some of the cans in case something unexpected and improbable actually happens. Having skills and knowledge to barter these for is useful, and unlike goods they do not deplete but improve with use.
They would.
With EM, you have absorption and reflection. Absorption converts the EM wave energy to heat, reflection just sends it away (or keeps it in the enclosure).
For EMP protection you need either of the mechanisms (or both combined). For other electronic warfare uses the choice gets more picky.
Generally, copper is best for the shielding. But it is also very expensive and not as good as steel for structural applications. So a thin copper sheet on the inside of the chamber will do a good job, and the signal can be further attenuated by the mass of concrete (especially when additives to make it somewhat conductive - ferrites and/or carbon/metal fibers may be good here, and the fibers can also help with the structural properties of the concrete) and the reinforcements (which are usually a cage with fairly low cutoff so high frequencies gets through - I think the original GSM phone frequencies got chosen on the basis of the usual spacing of rebar to face lower attenuation but I am not sure about it). For a Faraday cage, it can be made of mesh but the holes must be smaller than some fraction of the wavelength of the highest frequency you want to shield off.
With such copper/aluminium lining, you also have to pay good attention to the seams. A loose metal plate will act as an antenna instead of as shielding. Keep in mind that corrosion is a bitch and seams are prone to crevice corrosion and the shielding quality can degrade over years; so keep a margin in the design.
You can end up with a situation where a thick layer of concrete that you have to use anyway can outperform an optional thin layer copper add-on. Depends. Would require calculations, maybe simulations, certainly measurements.
The biggest worry will be the penetrations of the enclosure - the seams of the doors, the air ducts, and especially the points where antenna and power cables are getting in. You want extra good shielding/filtering there, and use fiber optics wherever you can get away with it.
Here, also keep quite a lot of margin for wear and corrosion. Especially the door seams will be at risk; anything that has to withstand movement or force is suspicious. Do not forget to do EMI audits once per couple years to make sure.
For additional points, don’t forget to bury some sensors and antennas under and around the bunker before the concrete gets poured. You want to have the same equipment the potential adversaries will use, to measure the efficiency of what you used (a Marx generator with a resonator can be used for making some pretty strong EM pulses, which you can run inside to check from the outside if they won’t get out (they will, they “won’t” just if your equipment is not sensitive enough - and the adversaries can afford better than you got, so use appropriately stronger signals for the tests) or how attenuated they are). Extra loops of certain optical fibers could be also used for sensing strains in the ground, which can be handy for structural reasons. Perhaps even in the concrete itself; think of them as integrated strain gauges, to feel the health of the structure decades later when things will be deteriorating. Do not forget to attach wires to the rebar, so you can use electrochemical measurements to assess the rebar corrosion (or attach sacrificial cathodes); it’d be a shame if such costly structure would not last at least a century in almost-new shape. And many such measurements can be apparently done with an Arduino and a handful of op-amps.
Todo: design a controller for a distilling rig. Design a spectrometer (ion mobility? FTIR? Raman?) to assess the output inline, to know with certainty down to almost a single drop when to switch output bottles to differentiate between the solvent-grade, booze-grade, and yummy-grade output.
You really don’t need a spectrometer, just a super accurate thermometer. Well, as long as you know your inputs. If you try and distill, say, lobster all bets are off.
I built a $50 glovebox on a whim some two years ago. I’d prefer these, as then we don’t have to bother with much of the airflow issues.
I have to design and try to 3d-print the glove ports. If I can print elastomers, even the gaskes could be done with relative ease; otherwise, rely on silicone goo.
A laminar flow hood is a glorified piece of furniture with some added air ducts, essentially. Less simple than a glovebox but still not that difficult if you get the HEPA filters. If built from scratch, likely to be quite above the $50, though.
What’s super-accurate? Millikelvin? Microkelvin?
And the control over the feedstock is the critical thing here. You may not have it. And a spectrometer itself can be highly useful for identification of salvaged (or produced) substances in general, at least to compare with known-good fingerprints.
As part of a closed system NPK cycle they would be pretty crucial, though we could sub Carp if you’d like. Both are edible, but you don’t have to eat them, and Carp have the advantage of enjoying lower temps.
It is the waste water that is valuable. That stuff is liquid gold for growing plants.
