There have been many researchers who discuss ancient technology, far superior to what we have today. This was covered extensively in the post Atlantean Technology and History | A Very Detailed Story of the Fall of Atlantis and their use of Crystals. Is this one such location where advanced technology was used?
David Wilcock spoke about a massive civilization buried beneath the sands of the sahara. Quite possibly this is part of that civilization or something completely different. Until a more extensive study is done, we can only speculate.
Two billion years ago, parts of an African uranium deposit spontaneously underwent nuclear fission — but the evidence suggests intelligent design.
The ability to moderate the reaction means that once the reaction was initiated, it was possible to leverage the output power in a controlled way, with the ability to prevent catastrophic explosions or the release of the energy at a single time.
For example, the water involved in the nuclear reaction must be extremely pure. Even a few parts per million of contaminant will “poison” the reaction, bringing it to a halt. The problem is that no water that pure exists naturally anywhere in the world.