This is the product of highly naive analysis. Out of a population of 300,000 displaced people, ~1,500 died over the span of a month. This is the same as the expected natural death rate assuming a lifespan of 90-100 years. If you dig into the causes of death the overwhelming majority are elderly people and the causes are listed as "fatigue" and "exhaustion". This "study" really just measured the number of people who died of old age, and attributed it to the disaster.
On 4 April 2011, radiation levels of 0.06 mSv/day were recorded in Fukushima city, 65 km northwest of the plant, about 60 times higher than normal but posing no health risk according to authorities.
Would you have ordered the evacuation of thousands of sick and elderly hospitalized people if they were all going to get an X-ray? a CT scan?
The amount of radiation from one adult chest x-ray (0.1 mSv). A chest CT delivers 7 mSv — 70 times as much.
0.4 mSv from a mammogram. https://www.health.harvard.edu/cancer/radiation-risk-from-me...
Radiation levels were about 2 chest x-rays every day.
6-16 mSv from CT scans.
The plant was still nowhere near under control on April 4 and needed constant attention.