[en] The zone refining process was applied to Pu metal containing known amounts of impurities. Rod specimens of plutonium metal were melted into and contained in tantalum boats, each of which was passed horizontally through a three-turn, high-frequency coil in such a manner as to cause a narrow molten zone to pass through the Pu metal rod 10 times. The impurity elements Co, Cr, Fe, Ni, Np, U were found to move in the same direction as the molten zone as predicted by binary phase diagrams. The elements Al, Am, and Ga moved in the opposite direction of the molten zone as predicted by binary phase diagrams. As the impurity alloy was zone refined, δ-phase plutonium metal crystals were produced. The first few zone refining passes were more effective than each later pass because an oxide layer formed on the rod surface. There was no clear evidence of better impurity movement at the slower zone refining speed. Also, constant or variable coil power appeared to have no effect on impurity movement during a single run (10 passes). This experiment was the first step to developing a zone refining process for plutonium metal

[en] Evaluation of the possibilities of uranium purification by the method of crucibleless zone melting using the C-701 and IEBZ-2 installations is carried out. The analysis of the metal for 17 metal and 5 non-metals microimpurities is made by the method of the spark mass-spectrometry. It is shown that the crucibleless zone melting is sufficiently effective for afterpurification of metal uranium. After two passes of the melted zone the amount of microimpurities in uranium sample decreased twofold in the average (from 0.8 to 0.4 at.%). The fact that the melted zone is hardy held with the surface forces and formation of chemical compounds films took place on the metal surface is the main difficulty in the process realization

No abstract available

No abstract available

[en] Three rare earth metals were zone refined under low contamination conditions. Where possible, effective distribution coefficients for the major impurities were determined, and these used to estimate the ultimate potential for zone refining as a purification technique for the rare earth metals. It is concluded that zone refining will be of most value for refining with respect to certain common metallic impurities. The metallic impurity levels at one end of a zone-refined gadolinium rod are believed to be the lowest ever recorded for a rare earth metal. (Auth.)

[en] An equation for the distribution of impurities over the length of a zirconium sample is derived and solved, applicable to conditions of non-crucible zone recrystallization in a vacuum with allowance for absorption by the metal of impurities from the residual gases in the vacuum chamber. It is shown that this impurity absorption is equivalent, in its influence on the efficiency of zone refining of the metal, to a reduction of the impurity distribution coefficient. The results of the calculation were checked experimentally. (author)

[en] Full text.We investigated theoretically the effect of temperature T on segregation coefficients K_eff of some impurities in molten tellurium obtained by zone refining process. Pfann's model was used to determine a series of 52 values of K_eff versus temperature for 13 different impurities. K_eff increased with temperature for most impurities. The activation energy of the 13 impurities was also determined. This series of K_eff was employed to calculate, for each impurity in tellurium molten zone, a series of 4 effective diffusion coefficients D_eff. A new expression of D_eff versus temperature T was demonstrated. The validity of this expression was confirmed by means of our experimental results. However, the diffusion of impurities was affected by temperature. Indeed, higher temperatures were not useful for tellurium molten zone. This work constitutes an important step toward an electronic grade purification of tellurium with good efficiency by zone refining process

[en] Short note

[en] Short note

No abstract available