Breaking it into a powder doesn't make it non radioactive but instead makes it more of a problem since it is harder to remove.
I had K do this in my story
Prisoners , though the other things you mentioned would indeed make an even more realistic K. In my story, Lois had used its glowing properties to escape a tunnel system, and had dropped it during a confrontation with Lex and at least once on the way out--then she discovered she had K dust all over her and had tracked it into Clark's apartment.
