Emergency monitoring and evaluation of Beijing radiation environment during the Fukushima nuclear accident

The article presents a retrospect aiming at Beijing radiation emergency monitoring work (from 12 March to 22 May) after the Fukushima nuclear accident, analyses the character about this nuclear accident radionuclide discharge, introduces the monitoring objects and methods such as γ dose rate's continuous automatic monitoring, aerosol monitoring and soil monitoring and so on. The monitoring data is analyzed and the influence of the leakage is evaluated. The monitoring results indicate that the range of γ continuous dose rate is in the range of Beijing background radiation level, the radionuclides are ¹³¹I, ¹³⁷Cs and ¹³⁴Cs. Based on the aerosol data, considering the external exposure from airborne radionuclide and internal exposure from inhalation, assuming the three radionuclides exist at the same time, the effective dose to infants, youths and adults are all lower than one of a million of effective natural background dose. (authors)