• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.627-632
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• 1998

Using an ammonium oxalate-ammonium sulfate electrolyte, a simple, quantitative, and fast technique for preparing sources for analytical alpha spectrometry was developed. To determine the optimum conditions for plating plutonium, parameters such as current density .and pH of electrolyte affacting the electrodeposition of the plutonium have been investigated. An optimized electrodeposition step for the determination of plutonium has been validated with a result of application to IAEA-Reference Soils. The new method of fallout Pu determination has been applied to environmental samples such as soil, sediment and moss samples in Korea.

• Analytical Science and Technology
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• v.19 no.1
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• pp.18-30
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• 2006

This paper describes the cumulative deposition of fallout Pu in soil and lichen at the present time and give the characteristics of fallout Pu deposits in the soil. In the soil of the forest, the accumulated depositions of $^{239,240}Pu$ were estimated to be in the range of 34.0 to $101.2Bq\;m^{-2}$ with an average value of $65.3{\pm}21.6Bq\;m^{-2}$. The average inventory of $^{239,240}Pu$ in the forest was calculated to be two times higher than that in the hill. Also, the deposited activities of $^{239,240}Pu$ in cultivated soil were significantly lower than those in the hill or forest. However, the cumulative depositions of fallout Pu in the volcanic ash soil on Cheju Island were much higher than those in the forest and hill soils. The measured activity concentrations of Pu isotopes in lichens and mosses showed large variations, due to characteristics of species and life span of lichen and moss colonies. From depth profiles, it was found that most of the fallout Pu has been accumulated in upper 10 cm layer of soil. Except for a few cases, the concentrations of $^{239,240}Pu$ in soil tended to decrease exponentially with increasing soil depth. Among parameters affecting the cumulative deposition of fallout Pu, organic substances and rainfall play an important role in the retention and relative mobility of fallout Pu in the soil. However, pH showed a weak correlation with the deposition of fallout Pu in the soil. From sequential leaching experiments, Pu was found to be associated predominantly with the "organic" and "oxy-hydroxy" fractions. Both the activity ratios of $^{238}Pu/^{239,240}Pu$ and $^{241}Pu/^{239,240}Pu$ in soils, lichens and mosses and the atomic ratios of $^{240}Pu/^{239}Pu$ in soils are close to those observed in the cumulative deposit global fallout from nuclear weapon testings. The results obtained from this research make it possible to interpret and predict the behavior of fallout Pu under natural conditions.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.439-444
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• 1997

In order to investigate organic association of fallout cesium, strontium and plutonium in the soil, soil samples influenced by fallout from nuclear weapon testings were treated with alkali (0.1 M-sodium hydroxide solution) to extract organic acids. After extraction, the resultant three fractions (sedimentary residue, humic and fulvic acid fractions) were subjected to the r-ray spectrometric analysis for $^{137}$ Cs, and radiochemical analysis for gosr and $^{239,240}$Pu. Alkali extraction experiments showed that a lot of $^{ 239,240}$Pu was extracted to organic acids from the soil samples, whereas most of $^{137}$ Cs and $^{90}$ Sr remained in residual fraction. Less than 10% of the total $^{137}$ Cs and $^{90}$ Sr was found in the organic fraction. The concentrations of $^{137}$ Cs and $^{90}$ Sr associated with humic fractions were higher than those with the corresponding fulvic fractions. It was found that more than 40% of the total $^{239,240}$Pu was associated with the organic fraction of soils. In contrast with $^{137}$ Cs and $^{90}$ Sr, $^{239,240}$Pu associated with vulvic fractions was much higher than in humic fractions.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.191-195
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• 2001

An accurate and simple analytical technique for low levels of fallout Pu in the environment was developed using an anion exchange resin. To develop the reliable determination of Pu isotopes in soil samples, decomposition of soil matrix, plutonium oxidation state adjustment on the anion exchange column and source preparation of Pu isotopes have been carried out. The optimum method of Pu isotopes with an anion exchange has been validated by application to IAEA-Reference soils.

• Analytical Science and Technology
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• v.17 no.6
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• pp.514-519
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• 2004

Soil samples collected from around the BOMARC Missile Site were measured for their activity concentrations and isotopic ratios of Pu and Am isotopes with particle sizes. The activity concentrations of Pu and Am in the BOMARC soil were remarkably higher than the fallout levels, and the activities decreased nearly exponentially with an increasing particle size of the soil due to a decreasing surface area. The activity ratios of Pu-238 / Pu-239, 240, Pu-241 / Pu-239, 240 and Am-241 / Pu-239, 240 observed in the BOMARC soil were much lower than those attributed to the nuclear reprocess plants and the Chernobyl fallout. Also, the atomic ratio of Pu-240 / Pu-239 in the BOMARC soil was remarkably lower than the fallout value influenced by the nuclear weapons testing and the Chernobyl accident. The atomic ratio of Pu-240 / Pu-239 was so close to the value of the weapons grade Pu released from the crash of a B52 plane in the Thule of the Greenland, such that the Pu isotopes detected in the BOMARC soil could have originated from the weapons grade plutonium.