Submitted a couple other times in the past as well, just not as much discussion:
In addition, knowing human nature and our propensity for conspiracy theories, there will be people in the future who think all those signs were put there to dissuade people from finding a massive buried treasure. (After all, the phrasing is pretty much what you would expect if someone had buried a treasure and wanted to make scare people from digging for it.
There are numerous long-term risks that don't involve the collapse of civilisation. The use of radioactive materials might become largely obsolete and the knowledge of it might become obscure trivia; such a society would have little awareness of the risks of radiation and very limited skills, equipment and infrastructure to deal with it. Geopolitical changes might put the nuclear waste site within the territory of an isolationist theocracy that rejects modern science. Changes in language might mean that the risks of radiation are fully understood, but the words and symbols we use to mark it might be incomprehensible.
Data rots with remarkable speed if it isn't maintained with constant vigilance. It's fairly common for construction crews to accidentally dig into an old sewer or an electrical conduit because records weren't properly maintained. Non-trivial quantities of radioactive materials have been lost due to accidents and administrative errors. Russia lost track of dozens of nuclear warheads and vast quantities of fissile material after the fall of the Soviet Union. Over a timescale of centuries or millennia, it's entirely conceivable that the location of a major nuclear waste site could be completely forgotten.
Even in both the cases mentioned, less than 10 total people died. Even without any signs, people living near it will most likely quickly develop taboos about the site.
Radiation has the worst PR department, ever. It is 2017 and we still have people railing against nuclear energy.
I'm in favor of atomic power but never dismissive of safety.
Now, one possible alternative would be to incorporate some of the waste into a monolith. People may not be able to decipher or heed warnings but they will probably avoid the thing that kills them. (Probably wouldn't make it past the ERB though)
I wouldn't be surprised if nearly every square mile of the US was closely monitored now, let alone in a thousand years.
> “Vehicle goes by at 70 miles per hour,” Giuliano told the crowd. “Agent is in the median, a good 80 feet away from the traffic. Signal went off and identified an isotope [in the passing car].”
> “Turned out to be a cat with cancer that had undergone a radiological treatment three days earlier,” Giuliano said.
More seriously, the danger is that we move beyond nuclear fission power and eventually forget it was ever used.
I don't know why they didn't do that exactly. I'm imaging there was some reason though.
I actually thought about that possibility. Figuring civilization will have collapsed several times, there's a good chance most people could look quite disfigured. I mean, post-apocalyptic wastelands can be harsh. At a minimum nobody will be exfoliating on a regular basis.
Then, if the meaning of certain common symbology happens to be reversed (e.g. arrows pointing away from the subject of interest), that's all it would take to mistake that image as marking the location of a miracle cure—a radioactive fountain of youth.
Regardless of how you read things you'd put those in the correct order since I'm fairly certain that the direction of time won't have reversed by then. It also avoids flipped meanings of glyphs like arrows.
They additionally convey a "contamination" of radioactivity that stays with the man over time.
They are markers hundreds of years old warning future villagers not to build below certain points (high-water marks for past tsunamis). In some locations they are still respected today.
Here's the marker at the SL-1 reactor burial site. This already looks dated, and it's only a few decades old. (It's not from 1961; it's from a later secondary cleanup.) The skull and crossbones is no longer used much for hazardous materials, and might be misread as a warning of chemically toxic waste. The road sign for "no pedestrians" is not really appropriate. The abstract radiation trefoil is only meaningful if you know what it means.
How do you communicate with a civilization that has no ties with to the current one?