You'd likely do less harm if you just dumped that waste in a heap on a roadside than if you shut down the plants and as a result ended up with more coal plans continuing to run. Where shutting down nuclear would result in wind or solar replacing it, you might be better off. Maybe hydro - with a very big caveat that the big risk with hydro is dam failures, which are rare, but can be absolutely devastating when they happen. For pretty much every other tech, the death toll is higher than the amortised death toll of nuclear with a large enough margin that you could up the danger of nuclear massively (such as by completely failing to take care of the waste) and still come out ahead.