If it was an easy problem then it wouldn't have taken 50 years to build a long term storage facility. Most problems are not easy, it just looks easy to outsiders.
It took that long because idiots routinely hold up the process with infinite questions. At some point you need to realize your existing behavior is worse and just move on, do not let perfect be the enemy of good enough.
It's an easy problem that doesn't really require a solution.
It doesn't really help with costs, so there's no hurry, and it's a political quagmire. So it just did not happen. (WIPP kind of happened, and is happening, but it's for non-commercial nuclear waste.)
