These can never be moved, changed, or cleaned up. But one of them could take an enormous amount of grouted radioactive defense waste, making both safer. I saw concrete blocks stored near the surface at Hanford. Concrete blocks are the alternative. They can be stored in concrete cellars just below the surface or be made small enough to move or be broken up.
Blocks are quite easy to monitor for radioactivity releases, temperature changes, and for removal.
This has been an eye-opening discussion. My main recommendation is that we store nuclear waste in cement packaging on the ground at military research and production sites where it was produced. Likewise, on-site storage of civilian fuel rods is the way to go for at least the next fifty years. In this way, waste can easily be repackaged or reprocessed in the future if the need develops. Remember that time is on our side, and haste is the biggest enemy.