Above: The Safecast Mac OSX app app map zoomed into the Fukushima Daiichi area after the most recent upload of data from inside the plant boundaries. The OSX and iOS maps allow the color scale to be adjusted to more easily differentiate either very high or very low dose rates.
Back in December 2013 we were happy to get our first data from inside the Fukushima Daiichi site, gathered and uploaded by user Neo-Logue. We wrote about it in this blog post.
As you can imagine, it’s difficult getting permission to enter the site, but we’re happy that since then several more Safecasters have gotten in and uploaded data afterward. In each case, like Neo-Logue, they were journalists, or tagging along with a press-related tour. Journalists are usually allowed to bring personal dosimeters, and the bGeigie has been allowed in for that reason. Based on conversations we’ve had with press people, TEPCO seems to have made it easier for journalists to obtain permission earlier this year. They are, of course, required to wear protective gear and are carefully escorted along set routes.
The second opportunity to gather data onsite was in January, 2014. Joe Moross, who had been providing technical advice to PBS science journalist Miles O’Brien for an impressive series of stories spent time onsite with Miles as a cameraman. Their tour included the Unit 4 spent fuel pool area. Both Miles and Joe had bGeigies with them.
Most recently, on Sept. 11 of this year, science journalist Ranga Yogeshwar and producer Rheinhard Bruning of the German public television network WDR / ARD brought two bGeigies onsite and collected more data. Ranga is a physicist and citizen science guru, in addition to being one of the best-known commentators on German TV. We’re thrilled and honored that he has been a very enthusiastic Safecaster since he first learned of our project earlier this year. Ranga built and modded his own bGeigie Nano, and for the visit to Daiichi, Rheinhart borrowed one which longtime Safecaster and filmmaker Michael Goldberg, who has been assisting this German TV team, had built for himself.
Caption: Comparing the areas where data was gathered on the four uploads from Daiichi to date. In these Google Earth screenshots, the readings marked as grey dots (kind of hard to see) represent the highest range; red, orange,and yellow are lower. (click to embiggen)
1) Neologue, December 2013; 2) Miles O’Brien and Joe Moross, January 2014
3) Ranga Yogeshwar, September 2014; 4) Rheinhart Bruning, September 2014.
Not all of these volunteers logged data from identical places, so it’s difficult to compare their readings closely. Radiation levels vary even more widely over short distances on the Daiichi site than they do elsewhere. Overall we could determine that the dose rates can be less than 1μSv/hr on some parts of the site, that areas on the well-traveled roads on the western half of the site are generally between 3-5μSv/hr, and that large areas, particularly near the reactor buildings and waterfront, are between 20-40μSv/hr. It’s notable that Joe and Miles logged dose rates up to 146 uSv/hr on the seaward side of the turbine buildings; Neo-Logue logged up to 203 μSv/hr nearby about 2 months earlier. It’s certain that these do not represent the highest doserates onsite. Other surveys, including TEPCO’s own, indicate several sample points outdoors near Unit 3 at over 1 mSv/hr (1000 μSv/hr); visitors are not allowed near such areas. And much of the interior of the reactor buildings themselves remain off-limits to workers due to much higher doserates.
TEPCO survey of whole Daiichi site, Sept 2014 (single-page pdf download) .
TEPCO survey of reactor area, Sept 2014. Note: levels are given in mSv/hr (single-page pdf download)
TEPCO survey of air dose rate in buildings, March 2013. Note: levels are given in mSv/hr (multipage pdf download)
According to TEPCO’s data, almost all of the reactor and turbine buildings have many areas over 100 mSv/hr inside, with some locations 1000 mSv/hr (1Sv/hr) and above. So far it has been impossible for TEPCO to get accurate measurements in many basement areas because the dose rates have been too high to allow extensive access by either humans or robots.
SAFECAST would be welcome the chance to conduct a full independent survey of the Daiichi site, and will continue to push for competent third-party verification of all aspects of decontamination and decommissioning, but we have not been encouraged by the official response to these suggestions so far. Nevertheless, with the help of willing volunteers like these, we’ve at least been able to confirm the general distribution and doserates of contamination onsite. We will continue to take advantage of similar opportunities to survey the Daiichi site as they arise.