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  • Author or Editor: S. Landsberger x
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Abstract  

Neutron activation analysis has been used to analyze sediment cores from the Rock River and two branches of Kent Creek, one of its tributaries, to determine the concentrations of thirteen heavy metals (Ti, Cu, V, Mn, As, Sb, Se, Cr, Ni, Sc, Fe, Zn, and Co) and two rare earths (Sm and La). The downstream sites of both the Rock River and the two branches of Kent Creek have elevated concentrations of several heavy metals including arsenic, antimony, and zinc. In addition, hundreds of parts per million of copper have been found in samples from the downstream site of the North Fork of Kent Creek. Toxicity tests of the sediment also indicate that the downstream sites are detrimental to lifeforms. Analysis of the data from the two branches of Kent Creek clearly indicate that heavy metal concentrations increase as the distance from the center of industrial activity (Rockford) decreases.

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Abstract  

Phosphates, naturally containing trace amounts of uranium, were examined using direct γ-ray spectrometry. Both normal and Compton-suppressed counting modes were utilized. The 1001 keV photo peak of the second daughter of 238U was chosen because of its isolation from other, potentially interfering peaks. The findings suggest that with the aid of Compton suppression, it is possible to quantify low uranium levels in phosphates using samples sizes of order 10 grams within an accuracy of 5%. The uranium content was determined in several sample types and was found to range from 60±4 to 70±8 μg/g, depending on the sample composition. This investigation also considered the effects of sample size, counting time, and counting technique as sources of precision maximization. This work has shown that only a small amount of phosphate is needed to determine the constituent concentration, instead of the standard several hundred grams of material.

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Thermal and epithermal neutron activation analysis techniques were used to analyze 27 Teflon air filters which were exposed to ambient air in Lisbon, Portugal, in February 2007. Tin was detected which is strongly suggestive of an anthropogenic source. Arsenic, antimony and copper were shown to be highly correlated, which is also suggestive of anthropogenic pollution. Trace element analysis of short- and medium-lived isotopes was performed yielding concentration information of various elements. Analytical sensitivities were enhanced using a Compton suppression system. Enrichment factor analysis shows that arsenic, tin, zinc, copper and antimony are at elevated concentrations in the Lisbon atmosphere.

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Abstract  

Open front hoods are routinely used to mitigate a worker’s inhalation hazard. However, it has been shown that these hoods leak contaminates, especially when a worker is performing work in the hood. Quantitative measurement performed in the past does not reflect actually working conditions, but instead tends to conservatively bias the measurement by placing the sampler inside the hood or forcing the air-stream out of the hood toward the sampler. In order to accurately measure the amount of material routinely leaking from an open front hood, an air sampler was positioned in front of the hood opening and samples were taken while a routine sample digestion process was done. The digestion process involved the heating of a surrogate mixture to dryness. Samples were taken with and without a worker present during the digestion process. The samples were then analyzed at the University of Texas using neutron activation analysis. The detection level using this method was low enough to measure the amount of aerosol escaping the hood. Based on these measurements, the capture efficiency of open front hoods for PuO2 is 84%.

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Summary  

Potassium is an extremely important major element to the human body. Potassium is made up of three isotopes with abundances of 39K at 93.1%, 40K at 0.0118% and 41K at 6.88%. It is also very well known that 40K with its 1.3 . 109 years half-life is a major naturally occurring isotope in the body and food. The usual way to determine total 40K is to measure the single 1460.8 keV photon from beta-decay. However, this procedure requires a significant amount of sample and typical counting periods of at least a day in well-shielded germanium counting system. Another approach is to determine total potassium via neutron activation analysis using the well known 41K(n,g)42K (T 1/2 = 12.8 h) reaction and then evaluate 40K using the usual activity equation A = l N. In our laboratory we have effectively used epithermal neutron activation analysis and Compton suppression to determine potassium in air filters and other geological material. Upwards to 10-15 samples can be analyzed in one day using only gram quantities of material. In such way one can increase the output of determining 40K by at least one order of magnitude. Results of a detailed investigation optimization of the methodology, quality control and detection limits will be presented for reference material and various food samples.

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In this paper, a description is made of the survey that was undertaken, for the first time, about the situation of radiochemistry activities in the Region of Latin America, comprising twenty countries from South America, Central America and the Caribbean. It became clear from this study that very strong differences exist between the countries and that most of the nuclear facilities in operation, such as nuclear reactors, hot cells, radiochemical laboratories and cyclotrons are concentrated in seven countries, accompanied by research and educational activities. A detailed study of the situation and trends in the Latin American countries is presented, as regards teaching and other activities related to Radiochemistry, as well as a series of suggestions for preservation of knowledge in the field.

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Abstract  

We have developed a PC based program for neutron activation data analysis using the FORTRAN and C languages. The routines are based on creating files associated with conventional ORTEC hardware and output software. The main features of the program include radionuclide identification, and the use of semi-automatic integration or the peak fitting SAMPO routine. Other developments are hard and soft copy records for detailed sample identification and particular irradiation, decay and counting procedures. Flux variations, high deadtime corrections, counting geometries, spectral and nuclear interferences, as well as uranium fission interferences are also automatically accounted for. The data output includes concentration values in %, ppm, g or ppb units with associated errors, while detection limits for each individual sample are indicated. Further data output can easily be generated which can be imported to most spreadsheet programs for various statistical uses. A future implementation to the program will include batch-file processing and automated self-absorption calculations for geological samples.

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Abstract  

The AL-R8 stainless steel sealed insert that is currently used for interim storage of plutonium pits at the Pantex facility in Amarillo, Texas, is designed to provide an inert storage environment for the plutonium pits for a 50-year service life. There is concern that the high chlorine content and absorbed moisture present in the packaging material, Celotex, may lead to corrosion of the container over time. The main objective of this study was to determine chlorine in the Celotex as well as in the various leaching procedures using neutron activation analysis.

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Summary  

Halides, particularly Br- and Cl-, have been used as indicators of potential sources of Na+ and Cl- in surface water and groundwater with limited success. Contamination of groundwater and surface water by Na+ and Cl- is a common occurrence in growing urban areas and adversely affects municipal and private water supplies in Illinois and other states, as well as vegetation in environmentally sensitive areas. Neutron activation analysis (NAA) can be effectively used to determine these halogens, but often the elevated concentrations of sodium and chlorine in water samples can give rise to very high detection limits for bromine and iodine due to elevated backgrounds from the activation process. We present a detailed analytical scheme to determine Cl, Br and I in aqueous samples with widely varying Na and Cl concentrations using epithermal NAA in conjunction with Compton suppression.

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Abstract  

The enormous utilization of phosphate rock and super phosphate derived from it have the potential of being an important factor in the contamination of aquifers with alpha emitting radionuclides and heavy metals. Both rock phosphate and super phosphate contain substantial levels of natural uranium, amounting to hundreds of ppm. Our study has shown that whereas the uranium series in phosphate rock is nearly in secular equilibrium, in super phosphate the226Ra and its progeny are depleted by 60–70%. This is a result of the chemical processing of the rock phosphate. On the other hand the super phosphate is much more soluble and can be expected to release its radionuclides to the environment more rapidly than rock phosphate. The present study explores the release of radioisotopes and heavy metals from phosphate fertilizers. Extensive analytical use has been made of a germanium well-detector/Compton suppression system.

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