[en] In the frame of the internal seminar of the INE the actual state of the running R and D projects of the institute is being presented and discussed. This report contains summaries of the presentations, which were given on this occasion, and the intention is to make it available for the public. Each contribution reflects the state of the related R and D project from July 2001 and does not represent necessarily a completed work. (orig.)

No abstract available

[en] In the frame of the internal seminar of the INE the actual state of the running R and D projects of the institute is being presented and discussed. This report contains summaries of the presentations, which were given on this occasion, and the intention is to make it available for the public. Each contribution reflects the state of the related R and D project from November/December 2000 and does not represent necessarily a completed work. (orig.)

[en] Glass powder and/or a mixture of oxidic mineral, non-clay materials is used as the matrix material. The ceramic tablets and the matrix material are filled or shaken, either individually in sequence, or mixed together into a container with simultaneous compression by vibration. The compressed mixture obtained in this way is heated to a temperature in the range of 1423 to 1523 K, kept at this temperature for one to three hours, and finally, slowly cooled to room temperature. (orig./HP)

[en] The titles of the 23 papers are: Objectives and status of work for establishing the protoype vitrification plant. Mass spectrometry for examination of simulated HLW glass using laser beam ablation. Corrosion behaviour of the WAK-HLW glass. Photoelectron spectroscopy of corroded HLW glasses. Barrier effect of the waste form spent fuel. Exact oxygen measurement in oxides and hydroxides. Oxidation state of uranium oxide from the natural fission reactor Oklo, Gabon. Barrier effects of the waste cask. Development work for laser-induced breakdown detection of colloids. Expanded model for description of the laser-induced breakdown effect in colloids. Radiation chemical effects in the near-field environment of a radwaste repository: γ radiolysis in 6 molal NaCl solution. Experimental determination of ion interaction (Pitzer) parameters for the TcO4- ion in the sea water salt system Na+/K+/Mg2+/Ca2+/Cl-/SO42-/H2O at 25 C. Charge distribution and bonding strength in chemical complexes of the lanthanoides and actinoides. Separation of Am(III) and Eu(III) by selective solvent extraction with N-donor extractants. ¹4C Dating of Gorleben groundwaters strongly affected by mineralization of sedimentary organic carbon (SOC). A study of the surface sorption process on silica by time-resolved laser fluorescence spectroscopy (I). Complexation of Cm(III) with tetraoxosilic acid. Thermal simulation of drift emplacement: 3D temperature analyses. Investigation into the compacting behaviour of backfilling material (salt rock detritus). Modelling calculations for description of re-dissolving processes in the presence of brine streams in the near-field environment of radwaste repositories. Modelling of the geochemical environment in a radwaste repository in salt rock in the presence of cement. Nuclide migration in the cap rock of the Morsleben radwaste repository. Determination of in-situ element distributions in the cap rock of the Morsleben radwaste repository (ERAM). (orig./CB)

No abstract available

No abstract available

[en] Post Irradiation Examinations of spent fuel performed at FZK/INE are focused on the understanding of the overall corrosion behavior of this waste form under conditions, which are as close as possible to the geochemical environment possibly encountered in a repository after an assumed groundwater intrusion. This comprises corrosion tests using real spent fuel samples and near field materials, under the anticipated conditions. Because of the deficit of the spent fuel matrix in oxygen extreme small quantities of O₂ are already sufficient to cause its very rapid oxidation upon the surface. Thus, in the case of preoxidation the UO₂ matrix dissolution rate will be enhanced orders of magnitude, which will not reflect the behavior of spent fuel from an intact rod. High efforts are necessary, to protect (i) the fuel samples itself and (ii) the entire experimental corrosion test arrangement permanently against O₂ uptake from air during the running time, and (iii) in particular during sampling of gases and solutions. To examine the impact of corrosion on solid materials very small particles are being separated by means of micromanipulator technique in association with light optical microscopy allowing steric view. Samples of interest are particles of fuel, new solids secondary phases, corroded container and backfill materials. The dose rate of the separated samples is low enough to allow their handling outside the hot cell, but their size is sufficient large to carry out SEM, EDS, ESCA and XRD studies. (Author)

[en] The immobilization of nuclear waste by embedding into an aluminum-silicate based ceramic matrix has been studied by using real TRU-wastes, as well as simulated high-level and TRU-waste mixtures from the nuclear fuel cycle. The aluminum-silicate ceramic matrix is less sensitive to the chemical composition of the waste, than other waste forms such as glass or Synroc. Therefore, a wide spectrum of waste streams with loadings of > 20 wt.% can be immobilized. Mixtures of 34 wt.% clay minerals (kaolinite, bentonite) and 66 wt.% reactive corundum were selected as raw materials. Waste streams investigated were: 1. dissolver residues, 2. ashes from the dry incineration of burnable TRU-wastes, 3. TRU-slurries, precipitated from different TRU-bearing waste solutions, 4. slurries, precipitated from medium level waste solutions, dissolver residues, dry incinerator ashes and denitrated high-level waste. Fixation of radionuclides is achieved either by inclusion into the microstructure of the aluminum-silicate or oxide matrix phases or by incorporation into the crystal structure of host phases, depending each on the chemical composition of the waste and the matrix raw materials. Leach tests were performed with TRU-waste ceramics, according to the IAEA-test, by using a MgCl₂-rich salt brine. Leach rates were found to range between 5 E-3 and 1 E-4 g/m²d at room temperature after a duration of about one year of total leaching time. The stability of the ceramics against α-irradiation was studied by doping it with 20 wt.% of Pu(238)O₂. After three years an accumulated α-dose of 8,33 E 9 Gy (1 E 19 α-decays/g ceramic) was reached, which exceeds the maximum accumulated α-dose of the ceramics under investigation after 100 000 years. The lattice constants of the matrix phases mullite and corundum were found to be only slightly enlarged (<2%). There were no signs of metamictization and no changes in the microstructure. (orig./BBR)

[en] The aluminium-silicate ceramic matrix KAB 78, developed for the Immobilization of TRU wastes, has been doped with 20 wt% of Pu(238)O_2, in order to irradiate the matrix by the same α-dose over a period of three years, as accumulated within a storage time of about 100 000 years, when loaded with the real TRU waste. The Pu(238)-doped ceramic KAB 78 was investigated, by means of ceramographic methods, while the accumulated α-dose increased up to 8.33 E 9 Gy (9.4 E 18 α-decays/g). Special attention was directed to the development of the microstructure, the crystalline state and the lattice constants of the matrix phases, as well as to stored energy, as a function of the accumulated α-dose. The lattice constants of the matrix phases corundum and mullite were found to be only slightly enlarged. Any sign of metamictization beginning has not been detected. Changes in the micro-structure have not occurred and the amount of stored energy has been determined to be less than 11 J/g. In order to study the corrosion behaviour of the Pu(238)-doped ceramic and ceramics loaded with real dissolver residues, leach tests were performed over a period of 214 days, using either Q-brine or Dl-water of up to 200⁰C. Leach rates, based on the total α-activity were found to be slightly higher, when leaching the Pu(238)-doped ceramics. Reaction zones of 150 up to 600 μm thickness were formed, with a significant decrease of Si, whereas the concentrations of Al and Pu remained unaffected