Data Shows Residents Near Daiichi More Exposed Than Previously Thought

Some recently released data that was retrieved from radiation monitors memory cards showed high levels of radiation before the reactor explosions in Fukushima. This series of events shows that a large number of people were exposed and still in the vicinity of the plant during the venting and explosions.

Futaba northwest of the plant saw a reading of  1,590 microsieverts per hour (1.59 mSv/h) by 3pm on March 12.  This is before unit 1 exploded at

The earlier readings are even more concerning.
0.18 microsievert/hour at 8:25AM on March 12, 2011 in Tomioka south of the plant. At 8:52AM on March 12, 2011, they measured 14 microsieverts/hour in Namie northwest of the plant. These are before the first venting.

These joined timelines of TEPCO, Wikipedia and these new radiation readings show the series of events:

5:44am Central govt. declares evacuation of all people within 10km of the plant (TEPCO)
6:33am Okuma town is evacuating (TEPCO)
8:03am Daiichi site supervisor sets venting estimated time for 9:00am (TEPCO)
8:25am .18 uSv/h (.00018 mSv/h) detected in Tomioka (Fukushima Pref)
8:27am Parts of the southern area near the plant are not evacuated (TEPCO)
8:52am 14 uSv/h (.00014 mSv/h) detected in Namie (Fukushima Pref)
9:02 am Confirmed south area near the plant is evacuated (we know by other data this is not true) (TEPCO)
9:03am Confirmed Okuma is evacuated (wiki) (this is inaccurate)
9:14am Team one opens the MO valve at unit 1, team two fails to open the AO valve due to high radiation (TEPCO)
10:17am AO valve is remotely opened (TEPCO)
10:30am radiation level at site boundary,  0.39 mSv / h (390 microsieverts/hour)  (wiki)
10:40am Radiation levels increase at the main gate of the plant (TEPCO)
10:50am Radiation at the main gate is 0.007 mSv / h (7 microsieverts/hour)  (wiki)
14:30 (2:30pm) Drywell pressure decreases, TEPCO declares radiation was released with the venting  (TEPCO)
15:00 (3:00pm)  1,590 microsieverts per hour (1.59 mSv/h) in Futaba near the plant (Fukushima Pref)
15:01 (3:01pm) TEPCO webcam shows steam venting out the vent stack for units 1 & 2  (wiki)
15:25 (3:25pm) Unit 1 explodes (wiki)

Radiation was being detected outside of the plant in the surrounding communites before venting and then in high levels after the venting, both before the first reactor explosion. What makes this more disturbing is that people were not actually evacuated out of the area at the time of the venting and the later explosion.

At the time of the explosion the mayor of Futaba was outside trying to help residents evacuate. In his testimony he mentions having debris from unit 1 fall all around them after the explosion. He cited that many people were still in Futaba at that time. So those people were being exposed most of the day and many were outside at the time the 1590 uSv/h reading was taken in Futaba.

The director of the Futaba Kosei hospital also witnessed the explosion of unit 1. His recount of events is documented here. He was informed by local police about 6am to evacuate the 136 patients at the hospital. After making some phone calls he decided to evacuate the hospital at 7:30am. He says they started evacuating at 8:30am but stopped after an hour after being told of the venting operation. A baby was born at the hospital by cesarean at that time. Some of the patients that could walk can be seen standing outside waiting for the evacuation bus at 8:30am. At 8:30am .18 uSv/h was documented at Tomioka south of the nuclear plant.

Local police were seen resting at the hospital at 11:00am, evacuation of the hospital had resumed by 12:30pm. (images of both below) The reading in Futaba at 10:00am was 6.90 uSv/h while this was going on.

At 1pm they still had 40 seriously ill patients they were unsure if they should move them due to their fragile condition. The hospital director was still trying to determine what was going on with the situation at the nuclear plant. The director was desperately trying to arrange 20 ambulances or helicopter transport for the 40 patients the afternoon of the 12th of March. He was then told to move to the nearby high school parking lot to meet SDF helicopters that would take the patients out of the area. At around 3pm they were taking patients out of the hospital on blankets to try to transport them to the high school to meet the SDF helicopter. At this time the radiation in Futaba was 1,590 uSv/h. The director also documents that at 4pm there was still a traffic jam of local residents in Futaba. This is a half hour after unit 1 exploded, the roads were still clogged with residents trying to flee the area. These people were all in the Futaba during the venting, high radiation levels and explosion of unit 1.

The director goes on to state that about half of the patients and staff were evacuated at the time when unit 1 exploded, he seems to be referring to those that did not leave in the initial evacuation. He also goes on to say 16 people were still at a home for the elderly and were not removed by SDF until March 13th.

Futaba was far from evacuated during the venting, releases and explosion of unit 1 as can be seen in the photos from Futaba Kosei Hospital. TEPCO may not have had another viable option at the time but to vent when they did to avoid a larger disaster and release. This does not absolve them from the liability for all these people unable to leave. The reactors were already leaking radiation before the venting efforts so there was public exposure even before that. This indicates there was likely some failure or leaking of the containment structures at Daiichi before the first venting. The later larger radiation release was due to venting of unit 1’s containment. The hydrogen explosion was mostly in the outer reactor building where less radiation was at the time.

This all does raise questions about the risks to the public if a reactor needs to be vented. The rural regions around the plant were unable to be evacuated in time to escape the larger radiation releases. How could a more populated area be evacuated in time? All of these people in Futaba and those that may have still been in other nearby areas such as Okuma, Tomioka and Namie were exposed to these large early releases of radiation. The mayor of Futaba has also said he was never informed of the venting and that residents are now being denied medical tests by hospitals at the request of the Fukushima University Health Survey. Many have had nosebleeds and hair loss,  they want medical tests to understand their health status.

The events on March 12th show some of the many failures of communication, public safety and how fast a nuclear disaster can become a danger to the surrounding community.

This article would not be possible without the extensive efforts of the SimplyInfo research team
Join the conversation at

© 2011-2023, All Rights Reserved Content cited, quoted etc. from other sources is under the respective rights of that content owner. If you are viewing this page on any website other than (or it may be plagiarized, please let us know. If you wish to reproduce any of our content in full or in more than a phrase or quote, please contact us first to obtain permission.



Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: