Quarterly reports of Ibaraki environmental radiation monitoring. The 180th and 181st reports, Apr 2017 to Sep 2017

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 measurement results of air dose rate, atmospheric dust, and fallout between April and June 2017, the effects of radioactive materials released from the Fukushima Daiichi Nuclear Power Station accident (hereinafter Fukushima nuclear accident) were observed. In addition, radioactive nuclides derived from radioactive materials released from the Fukushima nuclear accident were detected in the wastewater of the nuclear facilities. The monthly average value of the air gamma dose rate was between 33 nGy/h and 110 nGy/h, and due to the effects of radioactive materials released from the Fukushima nuclear accident, it exceeded the normal fluctuation range (upper limit: 100 nGy/h) at one point out of 98 points. The highest hourly value was 130 nGy/h. As a result of radionuclide analysis in fallout, Cs-134 was detected at one point and Cs-137 at all points due to the effects of radioactive materials released from the Fukushima nuclear accident. By the way, as the measurement results of I-131 at 5 points, it was not detected at all. As the measurement results of H-3 in seawater, it was not detected in all 12 sea areas. (A.O.)