But Fukushima is in Japan, and Japan and Germany feel much more similar, from a technological standpoint, than (West) Germany and the ex Soviet Union. Even though Fukushima was geographically much farther away than Tschernobyl, it somehow was "closer", politically.
"If it happens in Japan, it can happen here, too" - I know a few people that regularly vote / support the CDU (Merkels party) and most of them had this exact change of mind.
Chernobyl/Pripyat is in northern Ukraine, on the border with Belarus.
Ukraine is totally fine with nuclear power. Belarus plans to expand the existing plants. To the west, Slovakia's grid is mostly nuclear and is currently doing finishing touches on their new reactors. Hungary is also pro-nuclear.
The radioactive plume from Chernobyl then moved northwards, towards Baltics, reaching the populated parts of Scandinavia. Well, the grids in FIN and SWE are heavily nuclear-based, Finland is about to launch another 1500MW reactor.
So - the countries most affected by the Chernobyl disaster are unanimously pro-nuclear, while DACH countries, basically unaffected by it, are somehow in panic-mode whenever the word 'nuclear' is uttered.
Also, Austria did reject nuclear power in the 70s, before Tschernobyl, with one power plant (Zwentendorf[3]) already built but not yet running, via a very close referendum. So the anti-nuclear sentiment was already partly there (in Austria more than in Germany), but its very probable that Tschernobyl (and Fukushima) pushed enough people "over the edge" to give the anti-nuclear sentiment a comfy political majority across almost all political parties.
Why the other countries did not follow this trend, I don't know. They'll have their reasons :-)
[1] https://www.bfs.de/SharedDocs/Bilder/BfS/DE/ion/notfallschut... [2] https://science.orf.at/stories/3206079/ [3] https://en.wikipedia.org/wiki/Zwentendorf_Nuclear_Power_Plan...