Rei is an Angel Hybrid, and thus carries a core instead of a heart. Therefore, she might be able to withstand the nuclear impact and even absorb some of its energy. However, this would not be a good thing. Why? Because Rei's core would overload. Basically, she would turn into a ticking timebomb, with her various powers becoming harder and harder to control, and her body shifting into its true "Angel" form. At the very end, she might explode and create another miniature nuclear explosion.

Unless somebody kills her before then.

So, do any one of your characters wanna interact with/kill Rei as she slinks around the tower mutating?