Results of Radiation Monitoring in Niigata Prefecture due to the Fukushima Daiichi Nuclear Power Plant Accident（2011-2021 Compilation Report）

　In order to understand the impact of the accident that occurred at the Fukushima Daiichi Nuclear Power Plant (Tokyo Electric Power Holdings, Inc.), Niigata Prefectural Government has been carrying out measurements since the immediate aftermath of the accident under the relevant control systems.

　This report summarized the results of investigations conducted and made public by the prefectural government over the 10-year period immediately after the accident (March 2011 to March 2021).

Summary

　Immediately after the accident, Niigata Prefectural Government began to conduct and enhance monitoring of radioactivity measurements of radiation dose rates, fallout, river water, tap water, and agricultural, forestry, livestock and fishery products distributed within the prefecture. 

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　As Niigata Prefecture is located next to Fukushima Prefecture, westerly winds and mountains prevent the direct arrival of radioactive materials, and almost no artificial radioactive materials have been detected in Niigata Prefecture's river water, agricultural, forestry and fishery products.

　On the other hand, regarding the environmental behavior of radioactibe materials, it was found that radioactive cesium (total of cesium-134 and cesium-137), which is an artificial radioactive material that has flowed into the prefecture via rivers and fallout, is artificially concentrated in water purification plant sludge and incinerated ash. It has also been found that the transfer of radioactive material in specific organisms such as mushrooms, wild animals, freshwater fish, etc., concentrates/accumulates, and that sediment containing radioactive cesium that has fallen to the ground and run off to downstream areas due to rain, river water, etc., may move over time.

Overall Evaluation

　Niigata Prefectural Government has received the following feedback from the Investigative Committee for Fact-Finding Study on Circulation of Radioactive Materials regarding the results of surveys on radioactivity in the prefecture that were conducted over a period of 10 years since the accident (March 2011 to March 2021).

• Judging from the results of surveys carried out in Niigata Prefecture so far, radioactive materials derived from the accident at the Fukushima Daiichi Nuclear Power Plant have also been confirmed in this prefecture. However, the impact to the environment is limited, and the radiation level has no harmful effect on human health.
• In recent surveys, the presence of new airbone radioactive materials was not confirmed. The impact of the accident has disappeared in many samples with the passing of 10 years.
• It is necessary to continue to conduct surveys and confirm changes in concentrations of radioactive materials in wild plants, wild mushrooms, and the meat of wild animals whose concentrations were confirmed to have exceeded the standard values. As for other samples, it is desirable to review the necessity, frequency, method, etc. of surveys as appropriate according to policy purposes such as countermeasures against harmful rumors and for academic purposes such as understanding environmental behavior.

2011-2021 Compilation Report

★Click on each title will open a PDF file.

• Results of Radiation Monitoring in Niigata Prefecture due to the Fukushima Daiichi Nuclear Power Plant Accident (2011-2021 Compilation Report) [PDFファイル／12.89MB]
• Summary English version [PDFファイル／1001KB]

Japanese website is here!

　More detailed information such as data using figures in this report is presented in the following pages.

　https://www.pref.niigata.lg.jp/sec/genshiryoku/fukushimasasshi.html

Contact

　Nuclear Safety Management Division, Niigata Prefectural Government
　Address: Shinko-cho 4-1, Chuo-ku, Niigata-shi, Niigata, 950-8570
　Fax: +81-25-285-2975　E-mail: ngt130030@pref.niigata.lg.jp