XPS Investigation of ceramic matrixes for disposal of long-living radioactive waste products

The synthesis of ceramic matrixes for the long-term storage of highly active radionuclide wastes and determination of physical and chemical forms of radionuclides in them is one of the important problems in radioecology. It enables to create purpose fully materials for the long-term storage of radionuclides. In the present work the samples of ceramics [CaCe0.9Ti2O6.8(I) and CaCeTi2O7(II}] formed under various conditions were investigated with the X-ray photo electron spectroscopy. It is necessary for synthesis of ceramic matrixes, for the disposal of the plutonium and others tetravalent actinides. A technique was developed for the determination of cerium oxidation state (Ce3+ and Ce4+) on the basis of the X-ray photo electron spectroscopy spectral structure characteristics. It was established that the sample (I) formed at 300 MPa and T = 1400 °C in the air atmosphere contained on the surface two types of cerium ions in the ratio – 63 atomic % of Ce3+ and 37 atomic % of Ce4+, and the sample (II) formed at 300 MPa and T= 1300 °C in the oxygen atmosphere contained on its surface two types of cerium ions also, but in the ratio – 36 atomic % of Ce3+ and 64 atomic % of Ce4+. It was established that on the surface of the studied ceramics carbonates of calcium and/or cerium could be formed under influence of the environment that leads to the destruction of ceramics

X-ray photoelectron spectroscopy study of interaction of Np5+ with goethite α-FeOOH

Neptunyl NpO2n+ complexes on the surface of goethite α-(FeOOH) resulted from the interaction of neptunyl nitrate (NpO2NO3, 10-6 M) in the aqueous media with the background electrolyte (NaClO4) of ionic force 0.1 M (pH = 7.0 ± 0.2) were formed and studied with the X-ray photo electron spectroscopy. The X-ray photoelectron spectroscopy ionic and elemental quantitative analysis of the goethite and products of its interaction with neptunyl and plutonyl nitrates was carried out. It was established that during the studied neptunyl nitrate - goethite interaction Np4+ and Np6+ com pounds did not to form, while the complexes of neptunyl group NpO21+ containing Np5+ ions with oxygen, water and/or car bon ate ions in the equatorial planes did

38 Nu clear Tech nol ogy & Ra di a tion Pro tec tion –1/2005 X-RAY PHOTOELECTRON SPECTROSCOPY STUDY OF INTERACTION OF Np 5+ WITH GOETHITE a-FeOOH by

n+ com plexes on the sur face of goethite a-(FeOOH) re sulted from the in ter ac tion of neptunyl ni trate (NpO 2NO 3, 10-6 M) in the aque ous me dia with the back ground elec tro lyte (NaClO 4) of ionic force 0.1 M (pH = 7.0 � 0.2) were formed and stud ied with the X-ray pho to elec tron spec tros copy. The X-ray pho to elec tron spec-tros copy ionic and el e men tal quan ti ta tive anal y sis of the goethite and prod ucts of its in ter ac tion with neptunyl and plutonyl ni trates was car ried out. It was es tab lished that dur ing the stud ied neptunyl ni trate – goethite in ter ac tion Np 4+ and Np 6+ com pounds did not to form, while the com plexes of neptunyl group NpO