The cumulative radiation dose at MP (monitoring post) 32 in Fukushima Prefecture from March 23 to April 4, 2011 was 11,630 microsieverts (or 11.63 millisieverts), almost exceeding the OSHA 90-day limit for radiation worker of 12,500 microsieverts in 14 days.
My guess is if the radiation had been measured from March 11, 2011, it would have surpassed that limit long before March 23, 2011.
From Enformable's digging of the NRC FOIA documents, 3-page email dated April 9, 2011 says on page 3:
The U.S. 50-mile radius adequately protects public health, but the Japanese 20-kilometer (12 mile) radius may not protect the health of the general public, pregnant female radiation workers, or radiation workers who remain longer than 2 weeks near MP32.
MP32 remained MP32 in the Ministry of Education and Science (MEXT) monitoring data, until April 11, 2011 when the location was finally named. It was Akougi District of Namie-machi in Fukushima. Why was the location finally named that day? Because that was the day the government announced the planned evacuation zone that included Akougi and most of Namie-machi that was not already inside the 20-kilometer no-entry zone.
Akougi is located at 31 kilometers northwest of Fukushima I Nuclear Power Plant, outside the no-entry zone. The district was finally declared planned evacuation zone on April 11, 2011, because the annual cumulative radiation dose was expected to exceed 20 millisieverts.
There was a evacuation shelter in Akougi, with people living there until March 30, 2011.
According to the MEXT data, as of March 26, 2012, the cumulative dose at MP32 since March 24, 2011 is 125,760 microsieverts, or 125.76 millisieverts.
Here's the same information released by the Ministry of Education on April 6, 2011.