How? Neutrons slamming into water would break it apart, turn it into hydrogen and oxygen, and possibly activate the hydrogen into deuterium or tritium. But once it's hydrogen (or an isotope of it) it'll turn gaseous and be filtered off.
In order to become gaseous they need to combine with another atom of the same kind torn free, which is about as likely as combining with a free atom of another kind, form an HO radical and stay liquid.
