Doctoral Dissertations

Date of Award

6-1970

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

John A. Dean

Committee Members

George K. Schweitzer, A. E. Cameron, Carl A. McHauser, John B. Mamenstor

Abstract

The work presented encompasses techniques developed for the analysis of certain rare earth and actinide elements in solutions containing highly radioactive transuranium elements. Advantage was taken of the high inherent resolution and sensitivity of the rf spark-source mass spectrometer in the development of qualitative and quantitative procedures where an analysis can be made on a total sample of <1 to 10 μg. Parameters for the Associated Electrical Industries' MS-702 spark-source mass spectrometer were adjusted so that mass-to-charge ratios in the range of 10 to 310 could be subjected to qualitative analysis. For quantitative assessment of impurities in a transuranium solution, relative sensitivity factors were established with respect to erbium, the internal standard, for rare earth elements and for thorium, uranium, neptunium, americium, curium, berkelium, and californium.

A special glove box was designed, fabricated, and used on the source end of the mass spectrometer so that samples of the transuranium elements could be run safely. Transuranium element with α-emitting radioactivity up to 1010 dpm were processed through the source glove box and analyzed by the developed spark-source mass spectrographic technique.

Erbium was selected as the internal standard because it possesses a variety of isotopic ratios in the range of 1.22 and 245. Since the beam monitor has an unknown output for film work, erbium proved to be a very desirable internal standard. In addition to erbium's use as an effective internal standard, its multiple isotopic and abundance distributions rendered it valuable in calibrating each photographic plate.

The optimum sample excitation parameters and analyzing conditions were as follow: spark voltage, 30 kV; excitation pulse strength, 25 μsec; excitation pulse repetition rate, 100 sec-1; accelerating voltage, 20.2 kV; analyzer vacuum, 2 x 10-9 torr; source vacuum, less than 10-6 torr; and electrode systems of gold or graphite.

The relative sensitivity values for the rare earth elements were unity, and for the actinide elements, with respect to erbium, the range was from 1.61 to 2.65; uranium, 2.28; neptunium, 2.26; plutonium, 2.30; americium, 1.61; curium, 2.30; berkelium, 1.88; and californium, 2.1. The linearity of the erbium-spiked solution and spark-source mass spectrographic technique was demonstrated over a concentration range of 1 to 250. A reproducibility of about 3 to 4 per cent over the concentration range indicated that the relative sensitivity constants were independent of concentration.

The quantitative results for impurities of certain rare earth and actinide elements in a curium sample showed an average recovery of 100 per cent. The average standard deviation was 7.6% for an eleven-element mixture of Pr, Gd, Tb, Ho, Tm, Yb, Th, Np, Am, U, and Cm. The solution and spark-source method did not require any chemical separation prior to the analysis since inter-element effects were found to be negligible for this technique, The method was also applied to the analysis of lanthanum and cerium in Hastelloy N with good accuracy and reproducibility.

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