The greens have a terrible split between "environmentalists who want a drum circle" and "environmentalists who can add". The former think nukes are an unspeakable horror.
TBF, if you can add, you also realize that nukes are a mediocre fix at best, given that wind/solar/better efficiency get you where you want to be generally much cheaper. But if you're looking at "nukes or coal" it should be a no brainer.
Ok, I see your point, problem is nuclear is clean (wastes excluded) as long as everything is going just fine, but as soon there is an issue it can have a massive impact on the environment. I'm myself in favor of nuclear energy but I also can see its danger and understand why some peoples are against.