Band 4, Heft 2

A spectrophotometrical investigation of the tetravalent plutonium-arsenazo I complex was undertaken with the purpose of studying its analytical usefulness for the routine determination of trace amounts of plutonium in solution. The stock plutonium solution having systematically evidenciated the presence of great relative trivalent plutonium concentrations, some interesting conclusions could be drawn simultaneously for its corresponding complex by indirect means. A number of classical spectrophotometrical methods were used throughout this investigation with varying success due to the complexity of the system dealt with. In some particular instances full oxidation of the lower plutonium valence state towards the tetravalent state brought about by the arsenazo under certain acidity conditions and great excess of the reactive could be detected. Finally, a method for the routine determination of plutonium traces in solution is outlined, though its applicability to practical cases remains to be experimentally checked.

The solubility dependence of Pu(OH) 4 as a function of the p n of diluted equilibrating perchloric acid solutions has been studied by covering a wide interval of ps- From the experimental solubility data obtained and some theoretical implications, an attempt has been made to conciliate the extrapolated, experimentally found thermodynamic solubility product with DEBYE-HÜCKELS theory on ionic effects to account for the variations observed of the apparent solubility product throughout the different experiments carried out. The study of the apparent solubility product as a function of the ionic force has evidenced the existence of important discontinuities, which have been tentatively referred to a number of hypothesis based on the variation of the ionic activities of the present species, and on the impurities characterized in the precipitate systematically used as the starting material throughout this work. Some other interesting features of Pu (OH)! connected with this investigation have been studied in detail. Since the analysis of the precipitate employed has evidenced the presence of some percent amounts of plutonyl hydroxide, a study of the amphoteric characteristics of this species could be undertaken simultaneously. The method used for the calculation of the instability constant of the amphoteric process involved has been described in detail. A single ion-exchange experiment has been carried out with the aim of getting some information on the state of plutonium in very diluted aqueous solutions.

The extraction of americium (III) and the rare earth elements from ammonium thiocyanate solutions into xylene solutions of a quaternary ammonium salt (Aliquat-336) has been investigated. It was found that good separation of americium from rare earths can be achieved by using moderately concentrated ammonium thiocyanate solutions. Extraction coefficients for americium and R. E. were directly proportional to the amine concentration in the solvent. Extraction coefficients were affected by temperature changes, by the presence of various contaminant anions and by the nature of the solvent used, but separation factors between americium and R. E. remained essentially constant. Moderately high separation factors were obtained within the lanthanide group.

A radiochemical extraction procedure for the separation of tellurium isomers has been used to isolate an activity of 12.45 ± 0.28 minute half-life growing into samples of fission product tellurium. This activity is assigned to the ground state of 133 Te as it is shown to arise in the decay of 54-min component present in the fission-product tellurium and to decay to form the 21-h 133 I. The gamma-ray spectrum of 133 Te g shows prominent photopeaks at 0.307 ± 0.01, 0.406 ± 0.01,1.335 ± 0.01,1.709 ± 0.02, and ≈ 1.85 MeV.

Zusammenfassung Läßt man Wasserstoffperoxid auf eine saure RuO 4 -Lösung einwirken, dann bilden sich je nach Arbeitsbedingungen Ruthen(III)- oder -(IV)-Ionen. Es wird ein Verfahren beschrieben, nach dem man auf relativ einfachem Wege solche Ruthenlösungen durch Papierelektrophorese charakterisieren kann. Das ist besonders für die Untersuchung trägerfreier radioaktiver Lösungen bedeutsam.

A flow method during reactor irradiation to separate the recoiling species from the parent complex ion adsorbed on an ion-exchange resin was applied to the trioxalatochromium ion. The separable yield increased as expected: 80% for the dynamic method compared with 66% for the static method, at p H 2.0 by HNO 3 . The yield decreased with increasing pH with nitric or acetic acid as eluent, but the oxalic acid case showed a reverse trend. The specific activity increased with increasing p H in all cases.

Résumé La dégradation radiolytique du phosphate de tributyle a été mesurée, pour des mélanges binaires variés, à diverses concentrations et en milieu liquide et solide (cristallisé). Ces expériences ont montré qu'en général, en phase liquide, des composés aromatiques protègent ce solvant alors que certains hydrocarbures saturés (hexane, cyclohexane, dodécane) sensibilisent sa décomposition par les rayonnements ionisante. Ces effets sont attribués à un transfert d'ionisation du phosphate de tributyle aux composés aromatiques et des composés saturés au phosphate. La protection par les composés aromatiques a lieu également en phase cristallisée mais l'effet de sensibilisation est éliminé par cristallisation. Protection et sensibilisation ne sont pas observées dans le cas de la photolyse (1850 Å) de TBP. Par ailleurs, le cyclooctatétraène s'est révélé être un excellent protecteur, beaucoup plus efficace que tous les composés aromatiques que nous avons étudiés. Quant au cyclohexène, dont le potentiel d'ionisation est identique à celui du benzène, son rôle est protecteur contrairement au cyclohexane, mais son efficacité est faible.

Zusammenfassung Bei der Einwirkung ionisierender Strahlung auf Polystyrol, Polyacrylnitril und das Copolymere aus Styrol und Acrylnitril fanden wir, daß jedes der Polymeren linear mit der Dosis ansteigend ausschließlich Wasserstoff entwickelt. Bei Polyacrylnitril steht dies im Gegensatz zu Literaturangaben. Im Hinblick auf die Menge des aus dem Copolymeren entwickelten Wasserstoffs ist ein Schutzeffekt des Styrols auf Acrylnitril festzustellen, der bei kleinen Styrolgehalten (Molfraktion = 0,05) ein Maximum hat. Für diesen Schutzeffekt muß ein Energieübergang vom Acrylnitril auf das Styrol im Copolymeren verantwortlich sein. Er ist vom Aufbau des Copolymeren abhängig und besonders effektiv, wenn größere Sequenzen von Acrylnitril in der Copolymerkette vorliegen.

Iodine, bromine, and chlorine are determined by pile neutron activation in aqueous atmospheric samples. About 8 ml. of aqueous sample are irradiated, short-lived 38 Cl, 80 Br + 80m Br and 128 I are separated using carriers, selective oxidation and reduction, and CCl 4 extraction, and beta radioactivity is counted from solid silver halide sources. Six or seven samples per day can be analyzed with 5% accuracy.