First: I don't use, or plan on using, reactor craft. I have no experience, even testing in creative, on nuclear waste/explosions.
That said, it is my understanding that a meltdown produces very large amounts of radioactive blocks, which in turn spawn radiation entities. Over time, they decay, and the blocks that spawn the most entities decay fastest, and the most damaging of the radiation entities also decay fastest, leaving the long-lasting but lower-impact radiation things around.
The key question being time.
I'm not looking at "I have a waste container full of waste items", sticking a tile accelerator next to it, and letting that waste container clean up faster. I, and I think the others with this concern, are looking at "How do I recover the landscape faster?". Given that it takes many thousands (10's of thousands) of real-life years, I'm pretty sure that Reika's time scale would be in the many months, if not many years, of real time for a constantly loaded area to go clean.
Turning that down, to only several hours of gameplay, instead of several months/years of gameplay, is the goal here. Cleaning up the environment, so that the chunks that are polluted can be reclaimed.