From the TimesofIndia:
"Radioactivity levels in this area range from several hundred becquerels per square metre to thousands or even several million bequerels per square metre, the IRSN report, issued late Monday, said.
The 10 mSV derives from a calculation of exposure to at least 600,000 becquerels per square metre, emitted by caesium 137 and 134, which are long-lasting radioactive elements.
Of the 70,000 people in the zone identified in the IRSN report, more than 26,000 could be exposed to doses of more than 16mSv in the first year after the disaster.
Around 70,000 people, including 9,500 children aged up to 14, live in the area, "the most contaminated territory outside the evacuation zone," the agency said."
Live readings from Iitate, Japan. An average of 3 microSv/hr over a years time comes out to just over 26 millSievert
If the IRSN studied the MEXT map shown above, they would realize that they may actually be under-calculating doses. Some areas outside the exclusion zone are expected to get as high as 20-50 mSv/yr or more.