Well, it is fiction: in Isaac Asimov's stories there are "nuclear amplifiers" that magically (fiction without even an attempt of explanation) produce a beam of W-bosons, thus amplifying the (fictional) fusion reactions in spaceships making them explode.
In a part of these stories, those amplifiers are also used to fasten the natural decay of uranium.
As far as I know, fusion is limited by the weak interaction and if such a magical W-boson generating device really existed, it might increase the fusion rate.
But would that have any influence on the natural fission rate of uranium? I doubt but don't know.
