Neutron activation analysis with fission track counting was applied to a study of a variety of ceramic and plastic semiconductor
packaging materials. By using a high purity synthetic fused silic as a detector, the method has a lower limit for uranium
of 0.02 ppb. The highly sensitive, accurate technique permitted study of individual, highly contaminated glass fibers in molded
plastics and also studies of bulk ceramic and plastic materials.
Gamma-ray spectrometric survey analyses were used to screen raw materials available during the infancy of the optical waveguide
research program. Examinations of γ-ray spectra and semiquantitative survey analyses showed most samples to be insufficiently
pure for waveguide applications. Highly pure samples have been prepared successfully under carefully controlled conditions
when the purification process is adequately monitored by analyses. Radioisotope techniques and neutron activation analyses
were vital in the development of successful procedures for purifying various reagents from which glass could be subsequently
fabricated by melting techniques. Contamination sources during fiber production have also been detected by neutron activation
Major levels of boron in borosilicate glasses have been determined nondestructively by neutron activation analysis. In contrast to chemical methods for determining boron as a major component, the described nuclear method has few interferences and does not require chemical separation of boron prior to its quantitation. The effects of neutron self-shielding by boron (1 to 8% by weight) are examined, minimized by dilution of powdered samples with high purity graphite, and circumvented by comparative analyses. Results of the analysis of a series of glasses with increasing boron composition are 1.150±.005% and 7.766±.035% for the low and high members of the series. Accuracy of these results depends upon comparative analyses with the certified Standard Reference Material, SRM 93a (3.89±0.02% B). Once analyzed, the glasses are useful as secondary standards for alpha track counting, and also ion and electron microprobe analyses of glasses.
On mesure le cuivre 64 et le manganèse 56 dans du carbonate de sodium ultra pur par spectroscopie du rayonnement gamma après
élimination du24Na par passage sur colonnes de pentoxide d'antimoine hydraté (PAH); On a aussi déterminé le cobalt, le chrome et le fer par
détection spectrométrique non-destructive du rayonnement gamma du60Co,59Fe et51Cr. Dans le cas de CaCo3, après irradiation et dissolution, on a déterminé simultanément le64Cu et le56Mn, par une séparation radiochimique sélective à pH 3 à 4 avec un mélange de dithizone (H2D) et d'acide pynolidinedithiocarbamique (HPDC) dans CHCL3. L'interférence radioactive de47Sc et47Ca produits pendant 100 heures d'irradiation de CaCO3, étaient supprimées par extraction sélective de ce dernier en milieu HCl 5,0 M par l'oxyde de Tri-n-octylphosphine (TOPO)
0,1 M dans du cyclohexane. On a utilisé en mélange de 0,1 M Thenoyltrifluoroacetone (HTTA) 0,1 M et de TOPO 0,1 M dans du
cyclohexane pour enlever le47Ca à pH≥8.0. Après avoir éliminé l'activité des isotopes de la matrice, on mesure les pics photoélectriques de59Fe.60Co et51Cr pour doser ces impuretés.
A highly precise and selective method is described for the determination of traces of gold by substoichiometric extraction
from hydrochloric acid with tri-n-octylphosphine sulfide in cyclohexane following thermal neutron activation. Fundamental
aspects of the extraction system are discussed and results are reported for the determination of gold in an effluent from
a recovery process.
Combustion profiles of coal-limestone-paper blends were studied using thermogravimetric/ Fourier transform infrared spectroscopy
(TG/FTIR). The role of limestone in promoting the initial combustion of coal-paper blends and its ability to absorb sulphur
oxides were examined.
Authors:R. Golovchak, O. Shpotyuk, A. Kozdras, B. J. Riley, S. K. Sundaram, and J. S. McCloy
Radiation-induced physical aging effects are studied in binary AsxS100−x and AsxSe100−x (30 ≤ x ≤ 42) glasses by conventional differential scanning calorimetry (DSC) method. It is shown that γ-irradiation (Co60 source, ∼3 MGy dose) of glassy AsxS100−x caused a measurable increase in glass transition temperature and endothermic peak area in the vicinity of glass transition region, which was associated with acceleration of structural relaxation processes in these materials. In contrast to sulfide glasses, the samples of As–Se family did not exhibit any significant changes in DSC curves after γ-irradiation. The observed difference in radiation-induced physical aging between sulfides and selenides was explained by more effective destruction-polymerization transformations and possible metastable defects formation in S-based glassy network.
Authors:Hanxu Li, Xiang-Zhong Shen, B. Sisk, W. Orndorff, Dong Li, Wei-Ping Pan, and J. Riley
Improved thermoanalytical methods have been developed that are capable of quantitative identification of various components
of fly ash from a laboratory-scale fluidized bed combustion system. The thermogravimetric procedure developed can determine
quantities of H2O, Ca(OH)2, CaCO3, CaSO4 and carbonaceous matter in fly ash with accuracy comparable to more time-consuming ASTM methods. This procedure is a modification
of the Mikhail-Turcotte methods that can accurately analyze bed ash, with higher accuracy regarding the greater amount of
carbonaceous matter in fly ash. In addition, in conjunction with FTIR and SEM/EDS analyses, the reduction mechanism of CaSO4 as CaSO4+4H2 ↔ CaS + 4H2O has been confirmed in this study. This mechanism is important in analyzing and evaluating sulfur capture in fluidized-bed
Authors:H. Li, X. Yang, W. Tomes, Wei-Ping Pan, and J. T. Riley
The objective of this study was to examine the possible formation of chlorinated organic compounds during the combustion of blends of refuse derived fuels (RDF) and coal under conditions similar to those of an atmospheric fluidized bed combustion (AFBC) system. A series of experiments were conducted using a TG interfaced to FTIR. Additional experiments using a tube furnace preheated to AFBC operating temperatures were also conducted. The combustion products were cryogenically trapped and analyzed with a GC/MS system. The chlorination of phenols and the condensation reactions of chlorophenols were investigated in this study. A possible mechanism for the formation of chlorinated organic compounds such as dibenzodioxins and dibenzofurans, by chlorination and condensation reactions involving phenols, was proposed.