Uranium mines, ventilation systems, and lethal gases
I've been wrecking both my head and my Google-fu for a while, but to no avail. I hope you can help me clarify a couple of points.
Setting: sci-fi, fictional ice-covered planet. Advanced technology (think interstellar travels, laser beams and so on). Dystopia.
My MC works in an uranium mine. He's not aware of the real nature of what he's mining; he's an inmate on a prison-planet, he's been given a task, and the government keeps the whole thing under wraps. He has a standard mining gear (dust mask, hard hat, goggles, flashlight) and that's about it. Neither the government nor the guards (whose health is not affected by breathing in uranium/radon) really care about enforcing safety measures, as long as the steel boxes are filled with ore. There's a ventilation system up and running. Action takes place inside it.
- Ventilation system: it sends in fresh air and removes exhausts. I need to have big-sized air ducts (where a man can crawl and/or stand up), but it is plausible to have just them? I saw smaller ducts too, but I couldn't understand if they were used for fresh air, exhausts, or both.
- Radon is the decay byproduct of uranium. I know it's poisonous, but it doesn't kill at once. Is it correct to say that other lethal gases (methane, CO2, SO2...) are found in uranium mines too? If yes, each one of them is always present, or is there something that is never found in an uranium mine?
- If there's a lethal gas leakage in the ventilation system, is turning off all the fans the correct thing to do? I'd say yes, but I still wonder how you'd prevent it to fill the mine while fixing the leakage.
- I know that cool air is pumped into mines to contrast the heat. Would it happen on an ice-covered planet too?
Being a fictional setting, I can come up with a new kind of uranium/gas if needs be. I'd prefer to stick to real-life uranium, though.
If any of the terms I used is wrong, I'd be happy to know the correct one.
Sources: googled various combination of uranium mines/mining, lethal gas, and radon in two languages (English and Italian), professional sites for fans/air ducts/ventilation systems, World Nuclear Association, USMRA, .pdf/sites about safety issues in mines. Community tags.
(Mods, I don't know how to tag this)