There's nothing convenient about it. In a nuclear explosion there are trillions of neutrons flying outwards from the epicenter. Through simple statistical probability some will collide with something. Only other radioactive elements would be unstable enough to be fully destroyed by the energy of being slammed into by a neutron. Thus neutrons get stuck inside the nucleus of the atom.

However, without more protons to keep the forces inside the atom balanced it must be released. So the atoms themselves will become radioactive just naturally trying to relieve that imbalance.

Here are some of the radionuclides (atomic isotopes) made by a nuclear explosion.

https://en.m.wikipedia.org/wiki/Activation_product