The reaction to it was the real catastrophe
The actual “disaster” part of the Fukushima Daichi nuclear “disaster” was not worthy of the name. It is absolutely astonishing to me that 10 years later, the Tōhoku earthquake and tsunami which devastated coastal Japan is largely forgotten in the West. It killed more than 15,000 people, ruined whole cities, and rendered hundreds of thousands of people homeless. But I bet if you said the word “Tōhoku”, only a fraction of people would know what you’re talking about.
If you say “Fukushima”, on the other hand, everyone will know exactly what you meant. What they might not know, of course, is that there were no deaths directly attributable to Fukushima; it may have led to some detectable rise in cases of thyroid cancer, and the Japanese government attributed one lung cancer death to it later on, plus about 500 people died from the stress of the evacuation. Certainly it was nothing compared to the tsunami that caused it.
The Fukushima “disaster” was hardly worth the name, at the time. But the reaction to it was a real disaster. Global use of nuclear power fell by about 200 terawatt-hours; about 15% of the world’s total. This had an immediate impact — the increased use of coal in Germany alone is estimated to have contributed to an extra 1,100 deaths from air pollution a year. Nuclear is astonishingly safe; if you used it to power a medium-sized city for 14 years, on average one person would die prematurely as a result. If you used coal instead, it would be more like 350; oil, around 280. If the 200 terawatt-hours lost after Fukushima were replaced solely with coal, it would mean about 6,000 extra deaths a year worldwide.
And climate change is predicted to kill about 1.5 million people a year per year by 2100. Higher-emissions forecasts have higher predicted death rates. If the post-Fukushima panic caused a permanent reduction that might have saved 1% of those deaths, that’s 15,000 a year, worldwide; five 9/11s, or whatever your preferred unit of measurement.
Nuclear power is scary; it seems unnatural somehow, in a way that burning the compressed remains of ancient plants in huge combustion engines apparently isn’t. But it is orders of magnitude safer, and contributes far less to global warming.
The use of nuclear power only got back to its 2010 peak in 2019. Fukushima panic put us years back in our battle against climate change. Even though in itself it hardly mattered at all, it may end up being the single most ruinous disaster of the 21st century.