This sounds so ridiculuous, that I googled this claim. If one can even call it a claim, because you didn't finish that sentence to form a coherent argument.

The thing I found is this: http://large.stanford.edu/publications/coal/references/hvistendahl/

Don't bother reading this piece, because it doesn't even form its general idea very well. Hence the need for a later clarification, the very last paragraph," saying:

"*As a general clarification, ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage."

Like, yeah, I don't know if even that claim is true, but I don't have a hard time believing it. But even if we accept that, what kind of apples to oranges comparison is that supposed to be?

If you still want to support that claim, feel free to do so. But you better pick a better source, than the one I found...

Unless you do, I have to assume, that you're just regurgitating some propaganda.