A. G. Page

Electronic spectra and co-operative optical transitions in CaWO4:Tb3+ single crystal

Abstract The absorption, fluorescence and excitation spectra of CaWO4:Tb3+ single crystal were studied at 300 and 77 K. The polarization studies on laser excited fluorescence spectra were also carried out at 77 K. These studies led to the complete identification of two fluorescing states viz. 5D4 and 5D3 and of all the 7F ground multiplets of Tb3+ ions. Co-operative electronic transitions were observed for the first time in the low dopant concentration crystal and inferred as due to multi-polar interactions.

Chemical separation and ICP–AES determination of 22 metallic elements in U and Pu matrices using cyanex-923 extractant and studies on stripping of U and Pu

Comprehensive studies have been carried out on the extraction behavior of uranium and plutonium matrices using cyanex-923 extractant. The near total extraction of U/Pu and quantitative separation of 22 metallic elements at trace levels has been established using inductively coupled plasma-atomic emission spectrometry (ICP-AES). The studies carried out on back extraction of U/Pu from organic phase have established the near total recovery of these matrices into the aqueous phase using 1 M Na(2)CO(3) and saturated oxalic acid, respectively.

Role of Cyanex-272 as an extractant for uranium in the determination of rare earths by ICP-AES

A chemical separation procedure has been developed for the extraction of uranium from some of the crucially important rare earths using a novel extractant viz. Cyanex-272 (2,4,4-trimethyl pentyl phosphinic acid). The near total extraction of uranium and quantitative separation of rare earth elements has been validated using inductively coupled argon plasma - atomic emission spectrometry (ICP-AES). The recovery of some of the representative elements has been confirmed by radioactive tracer studies. The back extraction of uranium from the organic phase was carried out using a solution of 0.5M Na2CO3 which resulted in a near total recovery of uranium into the organic phase. These studies have enabled determination of sub ppm amounts of the analyte elements with a precision of 5% RSD utilizing prior chemical separation of rare earths from 1 g uranium samples in just three extractions with Cyanex-272.

Selective volatilisation of trace metals from refractory solids into an inductively coupled plasma

Abstract Feasibility studies have been carried out on the use of a graphite electrode assembly for the introduction of U3O8 solid samples into a continuously running low-powered argon inductively coupled plasma for the assay of trace metallic elements in uranium. The d.c. arc carrier distillation procedure has been adopted here for the selective volatilisation of analyte elements from the refractory matrix by injecting analyte vapours into the central zone of the plasma using Scribner-Mullin electrodes covered with a graphite lid having a central opening. The experimental parameters have been optimised for the direct determination of B, Be, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Na, Ni and Pb in U3O8 powders. The analytical performance of the method has been checked by analysing spiked U3O8 samples and is seen to be comparable to or better than d.c. arc methods for these analytes. These results indicate that the carrier-distillation-ICP combination shows promise as a sensitive and precise method for analysis of trace metallic elements in a refractory matrix with a complex spectrum.

ICP-AES determination of silver after chemical separation from uranium matrix

The separation of silver from a uranium matrix has been carried out using Cyanex-471X (triisobutylphosphine sulphide) in xylene. The effects of various parameters such as the Cyanex-471X concentration, the nitric acid molarity, the contact time and the nitrate ion concentration on the extraction of silver have been studied. The silver metal ion species extracted into the organic phase was found to be Ag(NO(3)).2S (where S is Cyanex-471X). The stripping of silver into an aqueous medium was carried out with 5% NaHSO(3), followed by its determination using ICP-AES.

Electrothermal atomisation atomic absorption spectrometric determination of silver, beryllium, calcium, iron, lead and tin in uranium without preliminary separation

Electrothermal atomisation atomic absorption spectrometric methods have been developed for the direct determination of Ag, Be, Ca, Fe, Pb and Sn in uranyl nitrate solution. Using 5-µl sample aliquots containing 100 µg of uranium, the detection limits for the analytes vary between 0.1 and 25 p.p.m. (on a uranium mass basis). The precision of determinations at an intermediate concentration was calculated to be better than 9% RSD. Interference studies carried out include the effect of the build-up of uranium in the atomiser and the effect of concomitant and major impurities on the analyte absorbance. A measure of the high accuracy of the determinations can be inferred from the analysis of a set of NBL reference standards.

Electrothermal vaporization — inductively coupled plasma-atomic emission spectrometry for trace metal determination in uranium and thorium compounds without prior matrix separation

Abstract The electrothermal vaporization (ETV) mode of sample introduction into inductively coupled plasma (ICP) has been examined for its suitability for the analysis of trace metals in uranium and thorium compounds without prior chemical separation of the matrices using atomic emission spectrometry (AES). The ETV interfaced with an ICP torch adapted for glove box operation, has led to determination of sub-nanogram amounts of Al, Be, Ca, Cd, Co, Cr, Cu, Mg, Mn, Na, Ni, Zn, Dy, Eu, Gd and Sm using 10 μl of the sample aliquot containing 200 μg of U/Th matrix with a precision of 1–2%RSD. The results obtained here especially for rare earths in the presence of the matrix are of significance.

Carrier distillation-ICAP approach for trace metal assay of U3O8 powder

ZusammenfassungDas Trägerdestillationsverfahren zur selektiven Verdampfung von Spurenmetallen in U3O8 im Gleichstrombogen wurde mit induktiver Probeerhitzung für ICAP angepaßt. Die experimentellen Parameter wurden für die direkte Bestimmung von Cd, Cu, K, Na, Ni und Pb optimiert. Die Leistungsfähigkeit des Verfahrens wurde mit Hilfe von Proben mit bestimmten Zusätzen sowie mit zertifiziertem Referenzmaterial überprüft (Standardabweichung 2–9%). Durch die Verbindung der Vorteile von Trägerdestillation und ICAP bietet sich eine Methode von hoher Präzision.SummaryA new approach for the trace metal assay of U3O8 powder has been described. The carrier distillation technique used for selective volatilization of trace metals in U3O8 with d.c. arc excitation is adapted for the release of analytes from the solid sample into the ICAP source by inductively heating the sample. The experimental parameters have been optimised for the direct determination of Cd, Cu, K, Na, Ni and Pb. The performance of the method developed here is tested for the precision and accuracy of determinations by analysing spiked U3O8 samples and NBL U3O8 reference standards (standard deviation 2–9%). The method appears promising to be developed as a highly precise analytical optical emission spectrometric method as it adds to the ingenuity of the carrier distillation method, the advantages of ICAP.

Direct determination of beryllium, cadmium, lithium, lead and silver in thorium nitrate solution by electrothermal atomization atomic absorption spectrometry

Abstract An electrothermal atomization atomic absorption spectrometric (ET-AAS) method is developed for the direct determination of Ag,Be,Cd,Li and Pb in thorium nitrate solution. The method offers detection of sub-nanogram amounts of these analytes in 100 microgram thorium samples with a precision of around 10%. A number of spiked samples and pre-analysed Th02 samples have been analysed to evaluate the performance of the analytical methods developed here.

Spectrographic determination of metallic impurities in PuO2

ZusammenfassungMit dem Verfahren der Trägerdestillation können 22 Elemente in Plutoniumdioxid spektralanalytisch erfaßt werden. Als Träger dient 5% Silberchlorid in je 100 mg. Mischoxid-Standards mit 10% PuO2 wurden verwendet. Bei der Untersuchung von Genauigkeit und Reproduzierbarkeit synthetischer Proben wurden für die meisten Elemente Abweichungen von 7–16% festgestellt. Matrixeinflüsse wurden ebenfalls untersucht sowie Analysenergebnisse für bestimmte Bezugsstandards mitgeteilt. Das Verfahren eignet sich für die Qualitätskontrolle von PuO2-Brennstoffen für schnelle Brutreaktoren.SummaryAn emission spectrographic method has been developed for the estimation of 22 metallic impurities in plutonium dioxide using carrier-distillation technique Silver chloride at 5% concentration in a charge of 100 mg has been used as the carrier. Mixed oxide standards containing 10% PuO2 have been used for the analysis of matching composition of plutonium samples. Precision and accuracy determinations of the synthetic samples indicate 7–16% deviation for most of the elements. The work described includes analysis of reference samples and matrix effect studies. The method is suitable for the chemical quality control analysis of plutonium oxide to be used for Fast Breeder Test Reactor (FBTR) fuel.