Authors:J. Rouchaud, M. Fedoroff, A. Dubertret, and V. Agafonov
The transition temperatures and ageing of shape memory alloys (SMA) depend on the chemical composition and purity. Methods for the deterrnination of trace impurities, doping and major elements in NiTi, CuZnAl and CuNiAl were developed using neutron activation analysis and -spectroscopy. For traces in Zn containing alloys, a chemical separation based on anion exchange resins was developed. Multielement analysis leads to detection limits ranging from 0.0001 to 1 g·g–1. For major elements, optimization of the irradiation and spectrometry parameters enables standard deviation better than 0.5%.
Authors:Dj. Čokeša, M. Marković, M. Soleša, P. Adžić, G. Škoro, S. Milonjić, and A. Kukoč
Seventeen honey samples collected at different sites during 1992 have been measured using the method of -spectroscopy. Measurements were performed by a low background high purity germanium spectrometer of a relative efficiency of 14.5% and an energy resolution of 1.7 keV. Using natural -ray sources to determine efficiency, it has been shown that out of 17 samples of natural honey only two (of meadow type) have specific activity of137Cs greater than 0.5 Bq kg–1. The remaining samples have the same137Cs concentrations as before May, 1986. Predominant activity in all samples comes from the40K radionuclide, indicating natural honey.
Sensitive environmental radioactivity measurement using direct -spectroscopy needs to be carried out under particular low-level conditions as the quantity to be determined generally is very close to the natural background. Passive shielding of the detectors in addition to electronic suppression of Compton background resulting from scattering of high energy -rays in the gemanium detector seems to be the most promising approach to obtain statistically well defined peaks within reasonable measurement time. Results obtained with a heavily shielded anti-coincidence spectrometer installed at the Research Center Jülich, ideally suited for the measurement of low-level environmental radioactivity in various materials are described.
The trace element levels in various organs of normal rats have been determined by means of thermal neutron activation followed
by high-resolution gamma-spectroscopy. Abundances for 11 elements (Cu, Mn, Fe, Zn, Rb, Sb, Se, Cr, Co, Cs and Sc) were evaluated
in the individual subjects. The present results were generally found within the ranges of the literature values, except for
ultra-trace elements. Reliability of the method was assessed by analyzing NBS standard reference materials, Orchard Leaves
and Bovine Liver. The trace element contents of the rat diet have also been measured, and comparison of them with those of
the rat organs was given.
Authors:D. Sims, W. Andrews, X. Wang, and K. Creber
In 1951, unsaturated prairie soil was contaminated with fission products and actinides. Fifty years later, in 2001, soil samples
were collected from the contaminated site. This paper describes the techniques used to analyze these samples, including gamma-spectroscopy
(GS) for 137Cs, neutron activation analysis (NAA/GS) for 238U, liquid scintillation counting (LSC) for 90Sr and inductively coupled plasma mass spectroscopy (ICP-MS) for 238U and 113mCd. As expected, ICP-MS was found to have the lowest detection level, while the techniques were ranked in order of increasing
uncertainty as GS, NAA/GS, ICP-MS and LSC.
Traceable non-destructive assay standards containing mixtures of well characterized americium and plutonium oxides were prepared by blending weighed quantities with a diatomaceous earth matrix and encapsulating in welded zirconium cylinders. Am and Pu retained in fabrication process materials (e.g., emptied blend bottles), termed holdup, was quantified by gamma-spectroscopy in order to accurately state the total nuclear material content of the standards. The observed holdup data indicate that the common assumption that Am and Pu holdup behavior is similar does not hold up well in the case of mixed oxides.
Authors:A. Lucaciu, L. Staicu, S. Spiridon, N. Scintee, and D. Arizan
A method was developed for the determination of element concentrations in structured water samples (water with high oligoelements content). Sixteen elements (As, Br, Ca, Ce, Co, Cr, Eu, Fe, K, La, Lu, Na, Sb, Sc, Sm, Zn) were determined in 4 structured water samples and one taken from the water tap. The samples were preconcentrated evaporating 1 1 at atmospheric pressure and obtaining 100–500 mg of dry residue. Measurement accuracy by -spectroscopy was 3–30% and it can be improved by increasing the measurement time. The method allows simultaneous multielement analysis of various water sources and may successfully be used in environmental pollution control.
A large number of fragments of ancient roman pottery has been analyzed for main constituents, minor and trace-elements using
high-energetic photon activation analysis followed by high resolution gamma spectroscopy. Especially the environmental influence
on the concentrations of the minor constituents and trace elements during deposition of the sherds in the soil has been examined.
Finally, a comparison has been made between analysis data of ancient pottery obtained by photon activation analysis, X-ray
fluorescence analysis and 14 MeV-neutron activation analysis.
Sediment samples of the High Dam lake were investigated for their137Cs,226Ra,228Th, and40K content, using low-level -spectroscopy. The results show that at the begining of the lake (500 km from the High Dam), where sediments consist mostly of sand, the level of137Cs is very low (0.1 Bq kg–1). The maximum value (22.3 Bq kg–1) was found 40 km from the wall of the High Dam, where the composition of the sediments is nearly 50% clays. The distribution of the natural nuclides226Ra,228Th, and40K shows a different trend.
Authors:J. Beiriger, R. Failor, K. Marsh, and G. Shaw
Following the accident at the nuclear reactor at Chernobyl, in the Soviet Union on April 26, 1986, we performed a variety of measurements to determine the level of the radioactive fallout on the western United States. We used gamma-spectroscopy to analyze air filters from the areas around Lawrence Livermore National Laboratory (LLNL), California, and Barrow and Fairbanks, Alaska. Milk from California and imported vegetables were also analyzed. The levels of the various fission products detected were far below the maximum permissable concentration levels.