There is correlation between opposition to nuclear power and ideology
Left-wing parties in general are opposed to nuclear power.
Nuclear power has several very distinct attributes:
Left-wing ideologies — especially greens, and reds that adhere to historical materialism — frown heavily upon on this. In the ideal green/left-wing red world, you are entirely self-sufficient and control your own means of production for utility and sustenance. Nuclear power — in its present form — flies in the face of this. Nuclear power requires extremely large and long-term investments. This requires large investors, not only utility companies but often conglomerates or industry groups, or backing on a national level. And once the plant is built, you as the consumer have no say about its operation. All you can do is use the power and pay your bill.
If you do not mind being the client of a power company, if you trust them to do their thing and not mess with the people dependent on their services... then nuclear power is quite all right. But if you are of the ideological persuasion that you should be in control over the production-means that sustain you, then nuclear power is not a good thing.
In short: if you are opposed to Big Corporate, you are generally also opposed to nuclear power, because nuclear power is Big Corporate personified
Finally, you ask...
Is support for nuclear energy correlated with support of "unnatural" technology, such as vaccination or genetically modified food?
Again it is a matter of your position towards big corporations. As I stated above, greens and left-wing reds are no fan of big corporations, because big corporations make you as the average citizen dependent on them and their whims.. and the greens/left-wings do not like that at all.
Now let us look at what you asked about:
- Vaccination. this concerns your health and physical well-being
- Genetic modification: concerns your food
Let us exemplify this by bringing out the most infamous of the bunch in the latter debate: Monsanto. Pragmatically speaking, Monsanto's GM products are safe and beneficial. Face it, they have been around for decades and if there had been any issues with them, we would have known by now. The upsides of their products blow the claimed (and unproven) downsides completely out of the water.
But Monsanto are right douches to work with. Because they require control over what you do with their products, even after you buy them! This is a pain in the rear end to be frank, and this is a genuine grievance against them.
But with Monsanto, and vaccinations, and nuclear power, you cannot get public support for your position and your struggle against big corporations with ideological arguments. You cannot say "Well their product is just fine... it is safe and efficient and fulfils my needs... but my ideology says I must hate them for being control-freaks about it". The reply to that is "Yeah yeah, whatever... you commie".
...and that is when the doomsday arguments are brought forth, because only with those arguments do you stand any chance to appeal to people that are not ideologically bothered by big corporations.