This still fails to address the fundamental question: Why do so many HNers think that environmental groups have infinite power to shape public policy around nuclear energy, while they have failed to succeed in any number of other campaigns, including ones that are more serious (climate change) and/or self-contained (commercial whaling)?

I'd suggest it's because the public discourse around these things are dominated by the talking points pushed by those same groups.

They may not be the only driver of that discourse, or even the primary origin, but they're arguably the face of that viewpoint.

Because being against nuclear was and still is to some extent the core idea that unites all green parties. There's nothing else they all agree on and nothing else that defines better the green vote.

Because of that, the green parties in most countries sold their votes in exchange of policies against nuclear as a first priority.

> being against nuclear was and still is to some extent the core idea that unites all green parties

Are there green groups that support whaling? Coal-fired electrical plants? Global climate change?

There are any number of other problems that "green parties" have in common. Having said that, it's important to note that Greenpeace and Sierra Club are not green parties, but non-profit organizations.

> Greenpeace and Sierra Club are not green parties, but non-profit organizations.

The line is much blurrier than you might think. The green parties originate directly from those movements and there's significant exchange with the non-profit world.

And yes, whaling or coal plants aren't pushed as much as nuclear as a subject, that's not even close.