Most of the "cost" of a nuclear accident is largely imaginary. What do I mean? The Government of Japan has convinced people that it's not safe to return to their homes and businesses in the areas around Fukushima. The science indicates that the levels are so low in the vast majority of the area, it *is* safe for people to go back, live their lives, and they'll be fine. However, when there's a small release of material from a nuclear plant that spreads over a very wide area, we say that all the property owners have to be evacuated and compensated for the property.
I'm sorry, but I don't accept that imaginary damages make nuclear power too expensive. If people had a rational, realistic knowledge of the real risks (or lack thereof) of living in the "Evacuation Zone".
Yes, there will definitely be some very real costs associated to cleanup - but the bulk of the "cost" apportioned to Fukushima are going to be imaginary damages for compensating people for their perfectly find and safe property.