Quarterly reports of Ibaraki environmental radiation monitoring. The 182nd and 183rd reports, Oct 2017 to Mar 2018

In the Tokai and Oarai districts of Ibaraki Prefecture, there are various nuclear facilities including nuclear power plants and nuclear fuel cycle facilities. To protect the environment around the nuclear facilities and to ensure the safety and health of the public, monitoring and measurement are carried out based on the environmental radiation monitoring plan and the results are reported in every quarter. As the results of short-term fluctuation surveys between October and December 2017, radioactive nuclides such as Cs-137 were detected from atmospheric dust and fallout, and total γ radioactivity was detected from the wastewater of nuclear facilities due to the effects of radioactive materials released from the Fukushima Daiichi Nuclear Power Station accident (hereinafter Fukushima nuclear accident). In the measurement of the air γ dose rate, the monthly average value was between 30 and 100 nGy/h, below the normal fluctuation range (upper limit: 100 nGy/h), and the highest hourly value was 120 nGy/h. As the results of radionuclide analysis in atmospheric dust, Cs-137 was detected at 4 points out of 15 points due to the effects of radioactive materials released from the Fukushima nuclear accident. As the results of radionuclide analysis in fallout, Cs-134 was detected at 1 point and Cs-137 at 3 points due to the effects of radioactive materials released from the Fukushima nuclear accident. As the radionuclide analysis results in milk, I-131 was not detected at all 5 points. As the radionuclide analysis results of H-3 in seawater, it was not detected in all 12 sea areas. (A.O.)