Those Underground Nuclear Bomb Tests? Dangerous Today?

During the 1950’s and 60’s, the US, France, UK, and USSR tested nuclear bombs by detonating them underground. Many of these tests were conducted-…but , as long as no radioactive material escaped into the atmosphere, they were pretty safe.
My question-as long as nobody ever excavates these test sites, are they likely ever to pose a danger to humans? Will the radioactive stuff just stay immobilized, until it decays away?

All radioactive materials will eventually decay, no matter where they are- it’s what makes them radioactive, after all.

As for the underground tests, yeah, the idea is that out in the Nevada desert, there’s not a lot of geological activity, and it’s pretty far from most everything (except maybe Las Vegas, which wasn’t always so big), so they could set them off out there and not threaten much of anything.

That’s why the UK did most of their tests in Australia, the French did theirs in Algeria, and the Soviets did them in Novaya Zemlya, and at Semipalatinsk, although at the latter they weren’t particularly careful about confining the tests.

Both Hiroshima and Nagasaki remained and still are today huge, populated metropolises…

I don’t know about other countries but the US has conducted underground nuke tests as recently as 1992.

My father was one of the guys that studied those tests.

An L.A. Times article from 2009 on potential water contamination from those tests. It did not help that, per the article, some of the explosion voids intersected the local water table.

I would not want to tunnel today into one of those old explosion voids, but I couldn’t give you a figure as to the level of radioactivity within the rubble.

At least in the US, most aboveground testing was done in the same place as the underground testing, so safety issues are largely theoretical.

There’s some amount of concern about the sites in New Mexico and Colorado where they did the “atomic fracking” experiments. The wells themselves are isolated, but irradiated gas has been moving in the subsurface somewhat faster than expected. Especially in the Colorado sites, there are producing wells somewhat nearby that could potentially become contaminated.

This made me wonder how much residual radioactivity was left by the bombings; a quick search brings up this column from Cecil; which says that just a month later, radiation levels had fallen to safe levels, with most of that decrease occurring in a few hours (all of the deaths from radiation poisoning and cancer afterwards were due to the immediate blast effects; there were no birth defects in children conceived after the bombings).

I don’t remember alot about what my dad did, but he had a spent artillery shell from the experiment he worked on. It was all twisted and melted looking. I got the impression from things he said that they put alot of different materials in the area they blew up to see what happened to them. Growing my brother and I both had issues with the thing and wouldn’t even touch it. My dad gave it to me awhile back to sell on Ebay to get money together for my cat’s operation. It pulled in a nice amount.

France kept conducting underground tests on Muroroa atolluntil 1996. Whether a coral atoll in the middle of the Pacific ocean is a good place to have conducted underground testing is something we’ll just have to find out about in time I guess.