In Chernobyl around 50 people died as direct consequence of the disaster. As far as I know there's no studies showing increased risk of cancer in the population that lived in and around Chernobyl at the time. If Chernobyl showed us one thing it is that radiation is not as dangerous as we believed.
I think it's worth assuming some reduction in life expectancy for some people, but notably the estimates of lost years of life have dropped year by year, and will likely end up being negligible.
I've said it before: we could have a Chernobyl every year, and it'd still be worth it (reducing deaths) if it got us off coal sooner...
However, all that was completely drowned by a collapse of life expectancy resulting from the chaos of the 90s. We're horrified at a few tens of extra cancers, but 100M men losing 10-15 years of their life due to socio-economic circumstances doesn't raise anyone's eyebrow
[0] https://en.wikipedia.org/wiki/Deaths_due_to_the_Chernobyl_di...