The only one I can think of right now is Dimensions of Loving by Chris Mulder, although it's not exactly what you're looking for. There's kryptonite powder, but not from a bomb, nor are they in Lois' apartment at the time. It is the second of two stories, the other being Love Beyond Measure, both excellent stories.

Cuidadora

"Honey, we didn't care if you were a Russian or a Martian... You were ours... and we weren't giving you to anybody." ~ Martha in Strange Visitor

"A love that risks nothing is worth nothing." ~ Jonathan in Big Girls Don't Fly