[cblades]

The DOE land on which ORNL sits has a massive stand that they used for testing of this idea. They'd suspend a reactor to test shielding effectiveness. You can see it from a few spots on I-40/I-75 and on Highway 95 going by the lab's west entrance.

[acidburnNSA]

It was called the Tower Shielding Facility. Pretty glorious. Small writeup here: https://www.ornl.gov/blog/ornl-reporter/lofty-ambitions