One person identified as having gotten cancer from Fukushima. Most of the cancers would be in a larger population and could not be distinguished from the large background of cancers. That doesn't mean they didn't (or won't) happen, or that regulation must assume they didn't/won't happen. Regulation is not like criminal law; radiation is not presumed innocent until proven guilty.
I agree that fossil fuel use should be aggressively reduced. In the past, that would have meant more nuclear. It does not mean more nuclear now. Reducing fossil fuel use has ceased to be an argument for nuclear construction.