NEWS
Justly famous gas discharge lamps of constant light intensity of 12 types from Cadmium to Zinc.
OSRAM LAMPS
SPECTRAL
Page 61
Reference
of the Ealing Catalog for complete description of this outstanding instrument. This is just one of the more than 3 0 0 instruments for the physical sciences offered exclusively by Ealing.
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ANALYTICAL CHEMISTRY
nium analyses was described by D. J. Fisher of Oak Ridge National Labora tory. It uses a stabilized printed-circuit operational difference amplifier com bined with a transistor current ampli fier to control the potential of the elec trode at which the desired reaction occurs. A portion of the electrolysis current is integrated by a stabilized printed-circuit operational amplifier connected as a time integrator, and the integral is read out as a voltage. The instrument is operated completely from an a.c. line and can be operated with either manual or automatic cutoff. The calibration is absolute ; results are com puted from Faraday's law. Accurate coulometric titration of small amounts of substances with high equivalent weights such as plutonium is possible because of the high stability of the integrator. Pyrometallurgical Processes. In operation of the Experimental Boiling Water Reactor (EBR II) at Argonne National Laboratory, there are unique problems involved in reprocessing the enriched uranium fuel elements. R. P. Larsen of Argonne described a meltrefining process. After a number of cycles, an equi librium alloy will be formed which con tains small percentages of the fission elements Zr, Mo, Ru, Rh, and Pd. The rare-earth elements, Sr, Ba, and sev eral per cent of the U react with the Zr0 2 crucible and are separated as an oxide dross. Since, in the projected operation of the reactor, Pu bred in the reactor blanket is to replace TJ235 as the fissile material in the core, it was necessary to ascertain whether or not the meltrefining process was also applicable to alloys of U, Pu, and fission elements. Therefore Pu and U analyses on both the ingot and dross materials were re quired. Plutonium is determined spectrophotometrically as the nitrate after it is separated from interferences; TJ is determined by an x-ray spectrometric method after it is separated from the Pu alpha contamination. The coefficients of variation for the U and Pu analyses are 0.9 and 1.2%, respectively. The colorimetric determination of zirconium in plutonium-uranium "fis sium" alloys was described by R. F. Buchanan of Argonne. Fissium is a spent Pu-rich reactor fuel which is com posed of small percentages of Fe, Ce, La, Mo, Ru, and Zn. The time required for duplicate analyses is about 3 1 / 2 man-hours. A sample of the alloy containing 40 to 100 γ of Zr in ION H N 0 3 is separated
from Pu and from some of the Pa by anion exchange. The effluent is ana lyzed for Pu, since more than 60 γ will interfere with the determination of Zr. The Ru is removed by fuming with HC10 4 . Uranium and Mo do not in terfere in reasonable quantities such as are encountered in this alloy. The Alizarin Red S lake is formed in 0.LV H N 0 3 , and the absorbance is measured with a Beckman Model Β spectropho tometer at 520 m μ. The color is stable for 3 hours and the determination is reproducible within 3 to 5% of the amount present. Application of liquid-liquid extrac tions to the separation of rare earths and cerium was described by J. .1. McCown of Argonne. This technique has not been used widely heretofore in radiochemical separations. In the melt refining of the U fissium alloys used as an equilibrium-type fuel at startup, ingots are produced con taining more than 0.5% each of Mo, Ru, Zr, Pa, and Rh, together with dross samples containing as much as 10% of rare-earth elements. Since the removal of rare-earth elements is of prime im portance in the fuel cleanup, it is nec essary to determine Ce and/or total rare-earth elements at several stages in the processing cycle. A solvent ex traction separation offers several ad vantages over tedious and time-con suming precipitation methods. Using di(2-ethyhexyl)orthophosphoric acid as an extractant, rapid and quantitative radiochemical methods were developed for Ce and for total rare-earth elements. Since each of the separation steps in both procedures is quantitative, it is unnecessary to de termine a yield factor. The solutions derived by re-extracting the organic phase are either plated for β counting or are gamma-counted with a well-type scintillation counter. The methods were tested on slices of U fuel element and irradiated U fis sium alloys. Several samples were also analyzed by standard precipitation pro cedures. The results compare favor ably. The spectrochemical analysis of "fis sium" for cerium and lanthanum has been studied at the Los Alamos Scien tific Laboratory, R. T. Phelps stated. This method has a coefficient of vari ation of 6% and comparable precision when amounts ranging from 20 to 200 y are determined. The recommended procedure involves dissolution of the solid sample in HC1, H N 0 3 , or HC10 4 ; oxidation of Pu to the sexivalent state with HC10 4 ; sep aration of Ce and La from Pu and other elements by precipitating them as the fluorides along with Eu which is added
