Ellis wrote:

"But to be objective about this, you are much more likely to die from coal fired plants than nuclear ones.
..In any case, I think the question I'm asking therefore is how much of the anti-nuclear sentiment in Japan now is emotional, how much was there before because of both Hiroshima and Chernobyl, and how much very rational fear in the Japanese context after Fukushima?"

I would not characterize the Japanese public's view of the health risks of radiation as "emotional," but rather as cold cognition, which is not to say that this cognition is necessarily correct. I would also not characterize their perceptions as something unique to Japanese public opinion. Essentially, publics in all developed nations, and in many developing nations such as China, view radiation as a public health risk that far outweighs the emissions from a coal plant. Indeed, Japanese public opinion in the 1970s and 1980s was arguably the most pro-nuclear in the world, with around 70% of the public supporting the expansion of nuclear power.

Moreover, this perception of the health risks of radiation is institutionalized in the form of quite conservative health standards for radiation exposure in Japan, Europe, the US, through the WHO, etc. Once you accept these standards, and treat low level radiation exposure as something more dangerous than a second-rate carcinogen, and you combine this with very low risk tolerance, nuclear power becomes too expensive and technically difficult to be a viable energy source, especially when you consider what to do with waste.
One English physicist who is a critic of these radiation standards said he would be willing to have low-level radioactive waste buried a hundred or so feet below his house. How many others would agree with him?

In a country that has just had the worst nuclear accident since Chernobyl, has had other smaller accidents, most notably Tokai-mura in 1999, and has been generating nuclear power for about 47 years, it is beyond ironic that new public health statistics show that cancer-death rates in Japan have hit a record low (heart and stroke death rates have as well, which makes one wonder what Japanese die of these days, assuming they are still mortal). Nonetheless, divorced from reality though they may be, I think we have to treat nationally and globally institutionalized conventions about the risks of radiation as a given.

Once you accept these standards as a given, then the issue is no longer the health consequences of radiation, but the consequences of these standards, and these standards are why the Fukushima nuclear accident has been so devastating for Japan. Many people have been forceably evacuated from their homes; others have fled out of fear and stress. Japanese agricultural exports (and domestic trade) have suffered big losses, so has Japan's tourism industry, even Japan's manufactured exports have had to face some fears that they are radioactive.

Finally, I don't think the large shift in Japanese public attitudes toward nuclear power since last spring had anything to do with revised perceptions of the health risks of nuclear power. Again, such perceptions appear to be essentially a constant. What has changed is the public's perception of the possibility of accident-free nuclear power, of the Japanese government's crisis management abilities, and most importantly of its ability to effectively regulate nuclear power to prevent accidents before they happen (think of all the ignored warnings regarding tsunami preparations). This shift in public attitudes is comprehensible, coherent, and arguably even a rational and essentially a reasonably reaction to the new information received over the past year.

Best,

Paul Midford