The sensible Swedes like planning ahead. This time its storage for nuclear waste from its own nuclear industry—storage that is supposed to last 100,000 years. Nuclear power currently provides 40 percent of Sweden's electricity from six operating reactors. The Swedes expect to fill the storage site—"60 km of tunnels buried 500 metres down in 1.9 billion year old bedrock"—sometime by 2080 at which time it will be closed.
For understanding whether the target of 100,000 years of successful storage is plausible, I suggest a trip back 100,000 years to understand what surprises might be in store over such an interval. One hundred thousand years ago the Bronze Age, the age when humans first started to refine and work with metal, was still 97,000 years in the future.
It might seem that not much happened in those 97,000 years, but actually a lot that could challenge such storage schemes did. For example, somewhere around 71,000 to 74,000 years ago Mount Toba, located in modern-day Indonesia, erupted in a supervolcano thought to be the largest in human history. The eruption was two orders of magnitude (100X) larger than another famous Indonesian volcanic eruption, Mount Tambora, which caused what is now referred to as "the year without a summer" in 1816.