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Abstract  

A previous paper reported the application of a method for determining226Ra by -spectroscopy. This paper presents important improvements which permit the determination of226Ra in the presence of large amounts of Ca. The method was applied to the analysis of226Ra and U isotopes in fish samples from the waters of the Grand Canyon.226Ra ranged from 0.05 Bq kg–1 /1.4 pCi kg–1/ to 0.17 Bq k–1 /4.7 pCi kg–1/.238U values ranged from 0.13 Bq kg–1 /3.5 pCi kg–1/ to 0.52 Bq kg–1 /14 pCi kg–1/ and234U values were between 0.23 Bq kg–1 /6.2 pCi kg–1/ and 12 Bq kg–1/ /326. pCi kg–1/.

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The thermal decomposition of ammonium metavanadate

II The kinetics and mechanism of the decomposition

Journal of Thermal Analysis and Calorimetry
Authors: M. Brown, L. Glasser, and B. Stewart
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Abstract  

In order to establish baseline information for current and future mining operations, water samples from the Colorado River and its tributaries have been analyzed for Ra-226 and uranium isotopes. Ra-226 was separated by coprecipitation on BaSO4 followed by alpha spectrometry. Ba-133 was used as a tracer for yield determination. Uranium was separated by a combination of BaSO4 precipitation and solvent extraction followed by coprecipitation on CeF3 for alpha spectrometry.Results indicate that radium and uranium levels in the Colorado River and its tributaries, except the Little Colorado River, are below the EPA specifications [1] for drinking water of 185 mBq/liter (5 pCi/1) for Ra-226 and 433 mBq/liter (11.7 pCi/1) for U-238. However, the specific sources for elevated uranium and Ra-226 concentrations in the Little Colorado River should be identified, and the potential impacts from leaching of the naturally exposed mineralization inside the Grand Canyon should be investigated.

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Abstract  

Methods for the analysis of129I and241Pu are described briefly. Neutron activation is necessary to achieve an adequate degree of sensitivity for the measurement of129I, but otherwise all laboratory manipulations are straightforward and use commonly-found, well-tried techniques. With these methods, both radionuclides can be measured easily in the terrestrial environment around a nuclear fuel reprocessing plant;241Pu is measureable elsewhere in integrating media such as undisturbed soil.

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The thermal decomposition of ammonium metavanadate, III

A structural view of the decomposition mechanism

Journal of Thermal Analysis and Calorimetry
Authors: M. E. Brown, L. Glasser, and B. V. Stewart

The kinetics and thermodynamics of the thermal decomposition of ammonium metavanadate (AMV) are combined with the structural information available for AMV, for the important decomposition intermediate, ammonium hexavanadate (AHV), and for vanadium pentoxide, the product of the decomposition in non-reducing atmospheres, to enable the atomic movements involved in the course of decomposition to be discussed in detail.

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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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