S. V. Godbole

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.

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.

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.

Trace metal assay of U3O8 powder by electrothermal AAS

Methods have been developed for the direct determination of Ag, Ca, K., Li, Mg, Na, Pb, Sn and Zn in U(3)O(8) powder samples by electrothermal AAS. Nanogram and lower amounts of these elements have been determined with a relative standard deviation of 6-16% in mg amounts of sample (either alone or mixed with an equal weight of graphite). The results for NBL reference samples were in reasonable agreement with the certified values. X-Ray diffraction studies on the residues left from the graphite mixtures after the atomization cycle, confirmed the formation of uranium carbide (UC(2)).

Spectographic determination of trace metallic elements in uranium using a mixed carrier: Ga2O3 and SrF2

ZusammenfassungFür die spektrographische Bestimmung von metallischen Verunreinigungen einschließlich Silber in Uran wurde ein Ersatz für den AgCl-Träger gesucht. Bei diesen Untersuchungen wurden auch die Bogenplasmaparameter für verschiedene Träger bestimmt. Als optimal ergab sich eine Mischung mit 6% Ga2O3 und SrF2 im Verhältnis 2∶1. Eine Trägerdestillationsmethode für die Bestimmung von 23 Elementen in einer 50 mg-Probe wurde entsprechend standardisiert. Die Genauigkeit ist in den meisten Fällen besser als 18%.SummaryDetailed investigations have been carried out to find a suitable alternative to the AgCl carrier for the estimation of a wide range of trace metallic elements including silver in uranium. These studies also include determination of arc-plasma parameters for different carriers. Based on the results of these studies, a 6 % mixture of Ga2O3 and SrF2 in 2∶1 proportion has been found to be the best carrier. A “carrier distillation” emission spectrographic method has been standardised for estimation of twenty-three elements in uranium with 50 mg charge on the electrode using this carrier. The precision of the method is 18% or better for most of the elements.

Direct AAS determination of Co, Cr, Cu, Mn and Ni in U3O8 by electrothermal atomization

ZusammenfassungDas entwickelte AAS-Verfahren geht von pulverförmigen 5mg-Proben aus. Nanogramm-Mengen der genannten Elemente können mit einer Genauigkeit im Bereich von 7–12% bestimmt werden. Die durch U3O8 verursachte unspezifische Absorption ist zu vernachlässigen. Durch Graphitzusatz (in der gleichen oder doppelten Menge der Probe) wird die Empfindlichkeit der Bestimmung verbessert und die Lebensdauer des Atomizers verlängert.SummaryAn atomic absorption spectrometric method has been developed for the determination of chromium, cobalt, copper, manganese and nickel in U3O8 by electrothermal atomization of 5 mg powder samples. Nanogram amounts of all the elements can be estimated with a precision ranging between 7–12%. The non-specific absorption due to U3O8 for these measurements is negligible. The use of graphite powder with U3O8 in equal or double the sample amount improves sensitivity for the analyte element and prolongs the life of the atomizer.

Determination of Cd and Li in U3O8 Powder by AAS With Carbon Cup Atomization

Abstract The flameless atomic absorption spectrometric technique has been applied for determination of Cd and Li in U3O8 by direct atomization of the powder samples in the carbon cups. Results obtained indicate that Cd and Li can be estimated in the ranges 0.05–2 ppm and 1–25 ppm respectively using 1 mg sample, Precision of the method for the two elements varies between 7–9%. Trace concentrations of transition elements do not affect their estimation.