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Abstract  

The effect of industrial pollution on the behavior of plutonium and americium was evaluated in a pine forest in the vicinity of a Cu-Ni smelter in SW Finland. Soil and vegetation were sampled at distances of 0.5, 2, 4 and 8 km from the smelter. The vertical distribution of plutonium and americium was studied in litter, organic layer and mineral layers. The amount of Pu and Am in the litter layer increased and that in the organic layer decreased towards the smelter. Concentrations of plutonium and americium in different vegetation species decreased in the order mushrooms > lichens (Cladina spp., Cetraria islandica) > Empetrum nigrum > Vaccinium vitis-idaea.

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Abstract  

The National Institute of Standards and Technology (NIST) seaweed Standard Reference Material (SRM4359) was developed through an intercomparison of 24 experienced laboratories. Several statistical techniques were evaluated for establishing reference values using the laboratories’ reported values including mean, midmean, median, Type B On Bias (BOB), Graybill-Deal, Mandel-Paule, Vangel-Rukhin, Cox and Maximum Likelihood. After reviewing the results from all these techniques, the median was chosen as a suitably robust way to calculate reference values. The uncertainties for the median values were estimated using bootstrap analysis.

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Summary  

Elérhetoség

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Abstract  

A radiochemical procedure is described for the measurement of 0.1 Bq 237Np in a solution containing similar activity concentrations of Th, U, Pu and Am as well as activity concentrations of 60Co, 90Sr and 137Cs one hundred times higher. A tracer of 239Np (milked from 243Am) was used as an isotopic spike for chemical yield determination. The relationship between gamma-counting geometries for ampoule (liquid) and NdF3 (solid) 239Np sources was established so that Np chemical yields could be measured by a comparative method. Efficiencies of alpha-spectrometers for 237Np in NdF3 sources were measured by a bootstrap technique. Two sets of experiments were designed and used to test out the procedure.

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Summary  

Minerals in the soil range from those that easily weather to those that are very resistant to the weathering processes. The minerals used in this study are referred to as “resistates” because of their resistance to natural weathering processes.1 It is also known that there are some resistate minerals that have a tendency to contain uranium and thorium within their crystal structure. These resistates can contain as much as 15-20% of the total uranium and thorium present in the soil.9 Do resistates dissolve in acids, particularly in the HF/HNO3 procedures, if not what can be done to the HF/HNO3 process to dissolve more of the resistate minerals? How would these acid techniques compare to the fusion method used for mineral dissolution? Could the resistate minerals contain considerable amount of uranium and thorium? These were the questions addressed in this research. The comparative data indicate that the use of H2SO4 in the dissolution process resulted in ~25% overall increase in the minerals dissolving therefore resulting in a higher yield of extracted uranium and thorium.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: I. Outola, S. Nour, H. Kurosaki, K. Inn, J. La Rosa, L. Lucas, P. Volkovitsky, and K. Koepenick

Abstract  

In 2004, levels of radioactivity exceeding federal drinking water standards were found by state laboratories in two separate areas of Maryland through gross alpha and beta screening measurements. It was desired to know which radionuclides were responsible for the activity and what effect water softener systems installed in individual households had on the mitigating problem. Non-destructive gamma-spectrometry and gross alpha-beta liquid scintillation measurements, as well as chemical separations followed by measurements of 222Rn, 226Ra and 228Ra, uranium and thorium isotopes, 210Po, and 210Pb were carried out by National Institute of Standards and Technology (NIST). The results of the studies indicated disequilibrium among the decay products in the Th and U decay chains had a major influence on the radionuclide content. Unsupported 210Po was found to be the predominant radionuclide in drinking water at one of the locations. Furthermore, the influence of the use of water softeners was found to be much more effective for radium than for uranium.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Inn, E. Hall, J. Woodward, B. Stewart, R. Pollanen, L. Selvig, S. Turner, I. Outola, S. Nour, H. Kurosaki, J. LaRosa, M. Schultz, Z. Lin, Z. Yu, and C. McMahon

Abstract  

Recoil ions from alpha-particle emission can contaminate surface-barrier detection systems. This contamination results in increased measurement uncertainty, and may require the replacement of expensive detectors. Disposable thin Collodion films are easily prepared and effectively retard the recoil ions when either directly applied to the surface of alpha-sources or as catcher foils between the source and the detector. The thin films are particularly effective for relatively low-level sources, but can sustain structural damage when exposed to high levels of recoil ions (tens of thousands per second) over extended periods of time.

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