Characterization of Radiocesium Levels and Fractions of 137Cs in
Soil Collected from Oguni, Date Using Manual and
Instrument Software Calculation Based on Covell Method
Arvin M. Jagonoy and Hirofumi Tsukada
Philippine Nuclear Research Institute, Department of Science and Technology,
Commonwealth Avenue, Diliman, Quezon City, Philippines
Institute of Environmental Radioactivity, Fukushima University,
1 Kanayagawa, Fukushima City, Japan
Institute of Environmental Radioactivity, Fukushima University, Kanayagawa, Fukushima City, Japan
Two core soil samples were collected from Oguni, Date which is located 55 km northwest from the Fukushima Daiichi Nuclear Power Plant accident area to determine the levels of radiocesium using High Purity Ge detector. Radiocesiums are toxic and a major component of nuclear reactions. The total levels of radiocesium in core soil samples for 134Cs is around 34,000 Bq/m2 and around 160,000 Bq/m2 for 137Cs. While for the top layer sample of 0-5 cm for 134Cs is around 20,000 Bq/m2 and around 100,000 Bq/m2 for 137Cs which is much lower compared to the first record (14 June 2011) of radiocesium deposition of about 300,000 Bq/m2 at Oguni area. In general, the manual and instrument software calculated results for radiocesium levels showed relative standard deviation of less than 5% for both core samples. The fractions of 137Cs in the top layer soil of the two cores were analyzed and the results were 5 and 3.9% for Fraction I (Exchangeable), 7.1 and 6.4% for Fraction II (Bound to organic matter), and 87.9 and 89.7% for Fraction III (Strongly bound). Compared this result with the previous study done on 137Cs fractions in soil around Oguni area agreed with the observation on its behavior that on a relatively undisturbed soil Fraction I tend to decrease, while Fraction III will increase, and Fraction II will have almost the same percentage value.
Nuclear power plants produce many radionuclides during nuclear reactions. 239,240Pu (half-life; thousands of years), 241Am (half-life; hundreds of years), 137Cs (half-life; tens of years), and 131I (half-life; days) are some common radionuclides that are produced during nuclear reactions (Rao 2001) which can be measured and characterized. Measurement and detection techniques are based on the scale or amount being measured and on particular radionuclide of concern.
In the event of accidental release of radionuclides from nuclear power plant such as in Chernobyl and Fukushima Daiichi Nuclear Power Plant (FDNPP), immediate assessment on the levels of radionuclides released in the atmosphere is important. Radiocesium, a toxic radionuclide and a major component during nuclear reactions, . . . . read more