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16.5: Radiation Contamination from Fukushima

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  • The 2011 Tōhoku earthquake and tsunami was the cause of a nuclear disaster at the Fukushima Daiichi nuclear power plant. The result was the release of radioactive isotopes. The total amount of iodine-131 and caesium-137 released into the atmosphere has been estimated to exceed 10% of the emissions from the Chernobyl disaster. [1][2] The radioactive isotopes were also released into the Pacific Ocean. The Japanese government has been unable to control the spread of radioactive material into the nation’s food. Radioactive material has been detected in produce, tea leaves, milk, fish and beef. [3] As of June 2011, the International Atomic Energy Agency (IAEA) has not confirmed long term health effects to any person that had been reported as a result of radiation exposure from the nuclear accident. [4]


    The primary releases of radioactive nuclides have been iodine-131 and caesium-137. [5] However, strontium [6] and plutonium [7][8] have also been found. These elements have been found in the air, groundwater, ocean and agricultural products. [9] Iodine-131 has a half-life of 8 days while caesium-137 has a half-life of over 30 years. [10]


    The Austrian Meteorological Service report estimated the total amount of I-131 radiation released based on extrapolating data from several days of observation at worldwide radionuclide measuring facilities in Freiburg, Germany; Stockholm, Sweden; Takasaki, Japan and Sacramento, California. During the first 10 days of the accident. [11] The report's estimates of total I-131 ranged from 10 PBq to 700 PBq. [11]


    The Austrian Meteorological Service report estimated the total amount of caesium-137 radiation released based on extrapolating data from several days of observation at radionuclide measuring facilities in Freiburg, Germany; Stockholm, Sweden; Takasaki. Japan and Sacramento, California. The agency estimated an average being 5,000 TBq daily. [11] Over the course of the disaster, Chernobyl put out a total of 85,000 TBq of caesium-137. [1]


    The United Nations predicted that the initial radiation plume from the stricken Japanese reactors would reach the United States. Nuclear experts reported that radioactive isotopes in the plume would be in low concentrations and would have extremely minor health consequences in the United States. [12] Radioactive fallout with the isotopes of iodine-131, iodine-132, tellurium-132, iodine-133, caesium-134 and caesium-137 was detected in air filters at the University of Washington, Seattle, USA. [13] Westerly winds were dominant during most of the first week of the accident, depositing most of the radioactive material out to sea and away from the Japanese population centers, with some unfavorable wind directions depositing radioactive material over Tokyo. However, Tokyo did not receive levels of radiation dangerous to human health.


    TEPCO estimated that 520 tons radioactive water leaked into the sea before leaks in a pit in unit 2 were plugged, releasing 2,800 TBq of I-131, 940 TBq of Cs-134, 940 TBq of Cs-137. [14] The regulatory safe level for iodine-131 and caesium-137 in drinking water in Japan are 100 Bq/kg and 200 Bq/kg respectively. [15] The Japanese science ministry said that radioactive substances were detected in tap water in Tokyo, as well as Tochigi, Gunma, Chiba and Saitama prefectures. [16] IAEA reported that drinking water in Tokyo, Fukushima and Ibaraki had been above safe limits. [15] Tokyo drinking water exceeded the safe level for infants, prompting the government to distribute bottled water to families with infants. [17] Iodine-131 and was detected in 12 of 47 prefectures, of which the level in Tochigi was the highest at 110 Bq/kg. Caesium-137 was detected in 6 prefectures but always below 10 Bq/kg. [15] On 27 April, radiation levels in Tokyo’s water supply fell to undetectable levels. [18]

    Agricultural Products

    The Japanese Ministry of Health, Labor and Welfare announced that levels of radioactivity exceeded legal limits and had been detected in milk produced in the Fukushima area. In Ibaraki, the IAEA confirmed that in some areas, iodine-131 was in milk and in freshly grown leafy vegetables, such as spinach and spring onions, therefore consumption was restricted. Iodine-131 was reported above safe levels and caesium-137 was reported at safe levels. Detection was reported in Ibaraki prefecture. [15] On 21 March, levels of radioactivity in spinach grown in open air in Kitaibaraki city in Ibaraki, around Samples from Chiba, Ibaraki and Tochigi also had too high levels in celery, parsley, spinach and other leafy vegetables. In addition, certain samples of beef mainly showed concentrations of iodine-131 and/or caesium-134 and caesium-137 above the regulatory levels. [15]

    From ChemPRIME: 19.0: Prelude to Nuclear Chemistry


    1. Fukushima radioactive fallout nears Chernobyl levels". New Scientist. 24 March 2011. Retrieved 24 April 2011.

    2. Peter Grier (April 26, 2011). "Was Chernobyl really worse than Fukushima?". The Christian Science Monitor.

    3. Hiroko Tabuchi (July 18, 2011). "Radiation-Tainted Beef Spreads Through Japan’s Markets". New York Times.



    6. Govt to monitor radioactive strontium levels". NHK. 9 May 2011. Retrieved 27 May 2011.

    7. TEPCO says plutonium found on quake-damaged plant grounds

    8. High concentrations of plutonium from the soil of rice field 50 km or more distant primary

    9. Radioactive steam released from nuclear plants

    10. INES - The International Nuclear and Radiological Event Scale pg. 16

    11. Accident in the Japanese NPP Fukushima: Spread of Radioactivity" (PDF). Retrieved 24 April 2011.

    12. Scientists Project Path of Radiation Plume By William J. Broad, 16 March 2011, The New York Times

    13. Fission Products in Seattle Reveal Clues about Japan Nuclear Disaster". Technology Review, MIT. 25 March 2011.

    14.. Outflow of radioactive water from the concrete crack near intake canal for Unit 2 of Fukushima Daiichi Nuclear Power Station

    15. Japan Earthquake Update". IAEA. 19 March 2011.

    16. Tokyo tap water has trace level of radiation". The Japan Times. 20 March 2011. Retrieved 20 March 2011.

    17. All clear on tap water, update". World Nuclear News. 24 March 2011.