Here's the trailer to what sounds like a very interesting feature documentary, Into Eternity, about the world's first permanent nuclear waste repository, Onkalo, which means “hiding place.” Located in Finland, the underground facility must last 100,000 years.
Once the waste has been deposited and the repository is full, the facility is to be sealed off and never opened again. Or so we hope, but can we ensure that? And how is it possible to warn our descendants of the deadly waste we left behind? How do we prevent them from thinking they have found the pyramids of our time, mystical burial grounds, hidden treasures? Which languages and signs will they understand? And if they understand, will they respect our instructions? While gigantic monster machines dig deeper and deeper into the dark, experts above ground strive to find solutions to this crucially important radioactive waste issue to secure mankind and all species on planet Earth now and in the near and very distant future.
For the above questions, we have some ideas here and here.