Observed radioactive materials in rain water after accident of the Fukushima Daiichi Nuclear Power Station

On March 11, 2011, Fukushima Daiichi Nuclear Power Station had been damaged by massive earthquake and huge tsunami, named as 'The 2011 earthquake off the Pacific coast of Tohoku'. A lot of radioactive materials were released from the power station into the environment. In order to observe radioactive materials and those fluctuations, rain water was measured by using gamma-ray spectrometer. ¹³⁴Cs, ¹³⁶Cs, ¹³⁷Cs, ¹³¹I, ¹³²I, ¹³³I, ^129mTe, ¹³²Te, ¹³³Xe, ¹⁴⁰Ba, and ¹⁴⁰La were observed in the collected rain water at Tokai-mura which is located at 100-km in the south of the power station. The release of radioactive materials from the power station into the atmosphere has not been observed since April 11 as a result of measuring the fluctuation for radioactivity of ¹³⁷Cs that is a typical radioactive material. (author)