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Abstract  

Simultaneous PIXE/PIGE was used to determine the concentration of 20 elements including N, O, F, Na, Mg, P, Ca (PIGE) and Cr, Mn, Cu, Zn, Cd, Ba, Pb (PIXE) in a number of animal and human rib samples, marrow, and the IAEA CRM Animal Bone (H-5). Samples and standards were bombarded with 2.5 and 4.0 MeV external proton beams. The minimum detection limits for most of the minor and trace elements ranged from 0.5 to 1.5 ppm. The sample preparation procedure for the nondestructive instrumental analysis of bone is discussed in detail. The analysis method is fast, nondestructive and offers selective analysis of the cortical and cancellous surface of the same bone sample.

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Abstract  

A radiochemical neutron activation analysis method has been developed based on pyrolysis followed by double gold amalgamation for the determination of mercury in solid samples. Accurate results were obtained for mercury in six standard reference materials of varying matrices, including coal. Linearity was demonstrated up to mercury concentrations of 10,000 ng/g. The method is capable of yielding precise, reproducible values with a detection limit of 5 ng/g for mercury in coal.

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Abstract  

A major objective of any laboratory course should be to stimulate students to extend their knowledge of the subject to specific problems. In the radiochemistry laboratory course at the University of Kentucky, we encourage students to make the transition from the textbook or laboratory manual to the real world through the use of a special project. This project, which typically replaces two normal laboratory exercises, is a short research problem that the student independently develops and executes. An overview of the incorporation of special projects into our radiochemistry laboratory course is presented.

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Abstract  

Although many areas of major national need depend critically on professionals trained in nuclear and radiochemistry, educational opportunities and student interest in this area have declined steadily for the last twenty years. One major contributing factor to the lack of student interest is that most students in science and chemistry courses are never introduced to these topics. This deficiency in science curricula, coupled with the negative public perception towards all things nuclear, has resulted in a serious shortage of individuals with a background in this area. We propose to address this problem by educating the educators — providing faculty from two- and four-year colleges and high school science teachers with the curriculum materials, training, and motivation to incorporate these topics on a continuing basis in their curricula. Two advantages of this approach are: (1) it will generate scientists with a basic understanding of this field and (2) as teachers incorporate nuclear topics, many students will have the opportunity to reflect on the role of science in a technological society.

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Abstract  

A new parametric approach to single-comparator instrumental neutron activation analysis (INAA) at the University of Missouri Research Reactor (MURR) was investigated. A detailed MCNP steady-state model of the MURR core was developed using the latest neutron data libraries to compute the continuous-energy neutron flux distribution. Intrinsic reaction rates were predicted by coupling the computed local flux distribution to the isotopic (n, γ) excitation functions for a range of elements present in standard reference materials (SRM). Using the predicted (n, γ) reaction-rates, the concentrations for the various elements were determined. The method worked well for all nuclides tested, including those with cross sections that are not proportional to 1/v such as Lu and Eu with agreements for most elements within 5% of the reference value.

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Abstract  

A detailed Monte Carlo N-Particle Transport Code (MCNP5) model of the University of Missouri research reactor (MURR) has been developed. The ability of the model to accurately predict isotope production rates was verified by comparing measured and calculated neutron-capture reaction rates for numerous isotopes. In addition to thermal (1/v) monitors, the benchmarking included a number of isotopes whose (n, γ) reaction rates are very sensitive to the epithermal portion of the neutron spectrum. Using the most recent neutron libraries (ENDF/B-VII.0), the model was able to accurately predict the measured reaction rates in all cases. The model was then combined with ORIGEN 2.2, via MONTEBURNS 2.0, to calculate production of 99Mo from fission of low-enriched uranium foils. The model was used to investigate both annular and plate LEU foil targets in a variety of arrangements in a graphite irradiation wedge to optimize the production of 99Mo.

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Abstract  

In January 2006 the beryllium reflector and graphite wedge that contained the k0 INAA irradiation position were replaced at the University of Missouri Research Reactor. Prior to replacement the average values of the flux ratio, f, and the epithermal non-ideality factor, α, were 57.4 ± 4.5 and 0.039 ± 0.012. The values of f and α immediately after the beryllium and graphite wedge replacement were 39.4 ± 0.6 and 0.021 ± 0.002. Subsequent measurements indicate that the neutron spectrum hardened with time, possibly due to the buildup of the 6Li atom density to saturation.

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Differential thermal analysis in an oxygen atmosphere and pyrolysis in vacuo combined with mass spectrometry have been used to follow the transformations occurring during the humification of vegetation. Two processes are indicated, one, apparently enhanced by liming consisting of oxidative degradation and the other corresponding to degradation of organic components with high thermal dissociation energies. At the base of some profiles the humus has characteristics close to those of translocated humus in freely drained soils.

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Abstract  

A 14 MeV neutron generator system with a new sealed tube (Philips 18604) was evaluated for total body in vivo neutron activation analysis (TBIVNAA). The neutron output, angular distribution, rise time, reproducibility of short irradiations and leakage of tritium were investigated. The 18604 tube meets all the requirements of TBIVNAA within its normal operating specification.

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Abstract  

A new instrumental epithermal neutron activation analysis procedure to quantitatively determine titanium, barium, and bromine in obsidian with improved sensitivity has been developed. The advantage of epithermal activation for Ti, Ba, and Br is demonstrated with multiple geological standards and the ability to determine arsenic in obsidian is demonstrated. The results for titanium are compared to previous electron-microprobe results for Kenyan obsidian.

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