Radiation monitoring in Japan

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Radiation levels in Japan are continuously monitored in a number of locations, and a large number stream their data to the internet. Some of these locations are mandated by law for nuclear power plants and other nuclear facilities. Some of them serve as part of a national monitoring network for use in a nuclear emergency. Others are independent monitoring stations maintained by individuals.

Interest in the levels of radiation all over the nation increased dramatically during the Fukushima I nuclear accidents. At that time, a number of people began streaming from monitoring stations, and some international organizations conducted special monitoring operations to assess the state of radiation levels near the power plant and throughout Japan.

Monitoring at Nuclear Power Plants[edit]

Regulations per the Japanese Nuclear Safety Commission prescribe some standards that a monitoring system at a power producing nuclear plant must adhere to. For the purposes of regulation, monitoring systems are divided into two categories.

  • Category 1: Design of the monitoring system has to fit S-class seismic criteria and have diversity and independence in the channels that constitute the system.
  • Category 2: These detectors are connected to the plant emergency power system.

Additionally, a condition for both categories is that it have the ability to monitor continuously and record its results.[1]

During normal operation, plants have to monitor gas and liquid radioactive effluent releases. The only type that requires continuous monitoring is radioactive noble gasses, although some require monitoring only for every discharge. Other types of radiation must be monitored weekly or monthly according to the regulations.[2]

Operating power plant sites stream readings from environmental radiation detectors located around or on periphery of the site, detectors measuring radiation levels leaving the plant stack (gaseous effluents), and detectors monitoring the radiation of the discharged waste heat water. Official monitoring websites of nuclear power plants in Japan are listed below.

Monitoring Organizations and Individuals[edit]

Radiation monitoring in Japan is performed and publicly streamed by a number of governmental agencies and non-governmental organizations and individuals.

SPEEDI Network[edit]

The Nuclear Safety Division of the Ministry of Education, Culture, Sports, Science and Technology streams information from a national network of detectors, called the System for Prediction of Environment Emergency Dose Information (SPEEDI). It has been called a "computer-based decision support system" by researchers, and its function is for real-time dose assessment in radiological emergencies. In 1993 it had been developed for domestic local range accidents and was in the process to scale up to a national scale emergency response program linked to local governments. A worldwide version (WSPEEDI) was under development.[3]

The government recommendation that people voluntarily evacuate from places in the 20–30 km range from the Fukushima Daiichi plant came after the Nuclear Safety Commission watchdog released forecasts based on SPEEDI measurements. It was found that radiation levels differed significantly based on geography and wind direction, and it was suggested that because of this, the way evacuation areas were being designated should be changed and become more detailed. The Yomiuri Shinbun calculated radiation doses based on data from the Fukushima prefectural government and found they corresponded with the forecasts.[4]

On the evening of March 15, Mr. Kan called Mr. Soramoto, who used to design nuclear plants for Toshiba, to ask for his help in managing the escalating crisis. Mr. Soramoto formed an impromptu advisory group, which included his former professor at the University of Tokyo, Toshiso Kosako, a top Japanese expert on radiation measurement. Mr. Kosako, who studied the Soviet response to the Chernobyl crisis, said he was stunned at how little the leaders in the prime minister’s office knew about the resources available to them. He quickly advised the chief cabinet secretary, Yukio Edano, to use Speedi, which used measurements of radioactive releases, as well as weather and topographical data, to predict where radioactive materials could travel after being released into the atmosphere. [5]

Data held back from the Japanese public[edit]

Data on the dispersal of radioactive materials were provided to the U.S. forces by the Japanese Ministry for Science already a few days after 11 March. The Japanese public got these official data almost two weeks later on 23 March 2011. This was revealed on 16 January 2012 by Itaru Watanabe, an official of the Science and Technology Policy Bureau of the Ministry of Education, Culture, Sports, Science and Technology at a meeting of the nuclear accident investigation panel set up by the Diet. The data were given to the US military in an attempt "to seek support from them" on how to deal with the nuclear disaster. The data provided by the computer program SPEEDI were difficult to interpret because it was unknown how much radioactivity was actually released. However, calculations were made with SPEEDI by the science ministry and NISA by assuming the amount of radioactive substances. And these results could have helped local governments and people in their choice of more appropriate evacuation routes.[6]

On 28 June 2012 NISA officials made their apologies to mayor Yuko Endo of Kawauchi Village for the fact that NISA failed to release the American-produced radiation maps in the first days after the meltdowns. All residents of this village were evacuated after the government designated it a no-entry zone. According to a Japanese government panel, authorities had showed no respect for the lives and dignity of village people. One NISA official apologized for the failure and added that the panel had stressed the importance of disclosure. But the mayor said that the information would have prevented the evacuation into highly polluted areas, and that apologies a year too late had no meaning.[7]

Ishikawa Lab, Hino, Tokyo[edit]

A lab in Hino Tokyo received major attention after the accident. The researcher was streaming readings from a Geiger counter bought six years ago on his website.[8]


The Pachube (pronounced Patch bay) site allows users to stream various sensor data to the web in real time and was put to use for monitoring radiation by a large number of users after March 2011. There was only 1 location streaming into Pachube before the accident, but a large number have since started to stream to the site. The community has converged on a standard way to report the information in order to disseminate the large variety of sources, such as detector model.[9]

The manager of developer relations at Pachube said that he foresaw a range of applications of the data, including cell phone applications. He also noted that the sensors will allow people to cross-check readings for accuracy and could inspire healthy skepticism. Pachube has hundreds of Geiger counters streaming, but there are still concerns that these may not be dense enough.[10]

In 2012 Pachube was acquired by Cosm which in 2013 was renamed xively.

DataPoke Foundation[edit]

The privately operated non-profit organization, DataPoke Foundation, performed independent monitoring of the Fukushima Daiichi NPP contamination dispersion. The project, Project:Fukushima, focuses on publicly publishing data, observations, measurements and dispersion plots of the Fukushima NPP contamination, and aggregating public opinion of these observations in order to reach a more complete understanding of the Fukushima Daiichi NPP catastrophe.[11]

RDTN (Safecast)[edit]

The RDTN.org was an early crowd-sourcing initiative to sponsor and assist in gathering, monitoring and disseminating radiation data from the affected areas.[12] RDTN intended their independent measurements to provide additional context for the radiation data reported by the official factors, to supplement and not to replace the data of the competent authorities.[13] RDTN successfully launched a micropatronage campaign to raise $33,000 in order to buy 100 Geiger counters to jumpstart their network.[14] In April hackers at tokyohackerspace prototyped an Arduino-based geiger counter shield to upload data from geiger counters including from RDTN supplied counters.[15] This prototype later developed into Safecast mobile geo-tagged radiation sensors. In late April, one month after its start, RDTN folded itself into Safecast (org) with the joint announcement that RDTN was rebranded as Safecast.[16][17] RDTN people attributed their success to crisis urgency.[18][19]

Monitoring by International Organizations in Japan[edit]

After the Fukushima disaster begun, some international organizations conducted operations in order to aid in emergency efforts.


Greenpeace sent radiology experts to the villages of Iitate and Tsushima in the Fukushima Prefecture. They found levels up to 100 μSv/h in the village of Iitate, and based on that, recommended that the government widen the 20 km no-go zone, which Iitate lies outside of, to at least 30 km. An official of the NSA said that high radioactivity levels detected by the NGO could not be considered reliable, although some members of Greenpeace stressed that their numbers corresponded in other areas.[20] The New York Times called the reporting by Greenpeace (with a well-known anti-nuclear position) a "guarded endorsement to the radiation data published by the Japanese government", due to the general correspondence between the numbers. Members of Greenpeace stressed that there has been distrust of the official data, and that their contention was not the radiation levels, but the action that was taken.[21]

United States Federal Agencies[edit]

Readings from aerial survey conducted by United States federal agencies after the Fukushima accident

Three days after the earthquake, the DOE, along with the NNSA sent 33 people and 8.6 tons of equipment to Japan, including consequence management response teams and a NNSA aerial system that took thousands of radiation readings over the next two weeks.[22]

Monitoring in Other Nations[edit]

The South Korea Korea Atomic Energy Research Institute operates 59 radiation monitoring centers across the nation of South Korea. After the Fukushima disaster begun, radiation monitoring activities increased across the country but radiation levels remained normal.[23]


  1. ^ Nuclear Safety Commission. Regulatory Guide: Regulatory Guide for Reviewing Radiation Monitoring in Accidents of Light Water Nuclear Power Reactor Facilities. September 2006.
  2. ^ Nuclear Safety Commission. NSCRG: L-RE-I.02. Guide for Radiation Monitoring of Effluent Released from Light Water Nuclear Power Reactor Facilities. September 1978.
  3. ^ Chino, M.; H. Ishikawa; H. Yamazawa (1993). "SPEEDI and WSPEEDI: Japanese Emergency Response Systems to Predict Radiological Impacts in Local and Workplace Areas due to a Nuclear Accident". Radiation Protection Dosimetry 50 (2-4): 145–152. Retrieved 11 April 2011. 
  4. ^ "Radiation doses spread unequally / Experts say govt should give more detail in designating evacuation zones". The Yomiuri Shinbun. 27 March 2011. Retrieved 11 April 2011. 
  5. ^ "Japan Held Nuclear Data, Leaving Evacuees in Peril". Herald-Tribune. 8 August 2011. Retrieved 8 August 2011. 
  6. ^ The Mainichi Daily News (17 January 2012) Radiation-dispersal data was provided to U.S. before Japanese public
  7. ^ JIAF (29 June 2012)Earthequake-report 455: NISA “sorry” for withholding US radiation maps
  8. ^ Austin, Bill (28 March 2011). "IPhone Versus Soviet Subterfuge Make Fukushima No Chernobyl". Bloomberg Businessweek. Retrieved 11 April 2011. 
  9. ^ "Citizen scientists help monitor radiation in Japan". BBC Programs. 8 April 2011. Retrieved 11 April 2011. 
  10. ^ Courtland, Rachel (25 March 2011). "Radiation Monitoring in Japan Goes DIY". IEEE Spectrum Tech Talk. Retrieved 11 April 2011. 
  11. ^ "Study: Modeling Fukushima NPP Radioactive Contamination Dispersion Utilizing Chino M et al source terms". Progressive mind. 27 October 2011. Retrieved 20 March 2012. 
  12. ^ "Crowd-sourcing aids Japan crisis". BBC News. 21 March 2011. Retrieved 11 April 2011. 
  13. ^ Madrigal, Alexis (11 April 2011). "The Open-Source Project to Build a Citizen Radiation Detection Network in Japan". The Atlantic. Retrieved 12 April 2011. 
  14. ^ Alvarez, Marcelino (May 7, 2011). "RDTN.org: Radiation Detection Hardware Network in Japan". Kickstarter. 
  15. ^ "Tokyo Hackerspace/RDTN Geiger Shield - Dev History". April 11, 2011.  |first1= missing |last1= in Authors list (help)
  16. ^ [Bonner], Sean (April 24, 2011). "RDTN is now Safecast". Retrieved 6 January 2014. 
  17. ^ "beh che ne pensi [well what do you think] RDTN is now Safecast". Retrieved 6 January 2014. 
  18. ^ "Crisis Mapping: RDTN.org". Retrieved 6 January 2014. 
  19. ^ "Interview, Marcelino Alvarez (Uncorked Studios, Portland, Oregon, USA)". BBC (6 min). 5 Apr 2011. Retrieved 6 January 2014. 
  20. ^ Hongo, Jun (31 March 2011). "NGO finds high levels in safe area". The Japan Times Online. Retrieved 11 April 2011. 
  21. ^ Jolly, David (30 March 2011). "Japanese Operator Says It Will Scrap Four Reactors at Plant". New York Times. Retrieved 30 March 2011. 
  22. ^ "DOE to Continue Radiation Monitoring and Other Assistance in Japan". Nuclear Street. 29 March 2011. Retrieved 11 April 2011. 
  23. ^ "S. Korea steps up radiation monitoring". United Press International. 8 April 2011. Retrieved 11 April 2011. 

External links[edit]