The Result of Radionuclide Concentrations in Fallout around Tokai Reprocessing Plant after Fukushima Daiichi Nuclear Power Plant Accident

Abstract

Monthly deposition samples were collected at the Nuclear Fuel Cycle Engineering Laboratories located about 115 km south of the Fukushima Daiichi Nuclear Power Plant (NPP), and the radioactive nuclides were analyzed. Although radionuclides such as ¹³¹I, ^129mTe-¹²⁹Te and ¹³²Te-¹³²I with ¹³⁴Cs and ¹³⁷Cs were observed by gamma spectrometry at the early time of the Fukushima Daiichi NPP accident, only ¹³⁴Cs and ¹³⁷Cs were detected as of September 2011. The annual depositions of ¹³⁴Cs and ¹³⁷Cs were about 19,000 and 17,000 Bq m^-2, respectively in March 2011-February 2012 after the accident. Moreover, ⁹⁰Sr was detected in some samples. Monthly ⁹⁰Sr deposition in March 2011 was 5.1 Bq m^-2 month^-1 and then decreased after that. On the other hand, ^{239, 240}Pu concentration was the same level with the concentration before the accident.