Organischen Matrices wurden zur Fixierung schwach- und mittelradioaktiver Abfälle in verschiedenen Bereichen der Kerntechnik verwendet. Zwar war und ist die Einbindung dieser Abfälle in Zement eine einfache, kostengünstige und vielfach genutzte Methode, Zement hat aber auch Nachteile. Diese Zusammenfassung liefert einen Überblick über die Ergebnisse von F

Es werden die Ergebnisse von Arbeiten zur Korrosion von Stählen und keramischen Werkstoffen in salinaren Lösungen beschrieben, die für die Herstellung von Behältern für Wärme entwickelnde Abfälle sowie für schwachradioaktive Abfälle geeignet sind. Bei den Experimenten wurden die zu erwartenden Temperaturen und die einem Endlager im Steinsalz unter Störfallbedingungen auftretenden Salzlösungen unterstellt. The results of investigations of the corrosion of steels and ceramic materials in saline solutions are described, which are suitable for the production of containers for heat-generating waste forms as well as for low-radioactive wastes. In the experiments, the expected temperatures and the salt solutions occurring in the rock salt under a accidental conditions were assumed.

Es wird ein historischer Überblick über die seit Ende der 1950er Jahren betrachteten Optionen zum Umgang mit flüssigen hochradioaktiven Abfällen vorgestellt. Ausgehend von den Randbedingungen der Wiederaufarbeitung von abgebrannten Kernbrennstoffen werden mögliche Verfahren und Strategien zur Verfestigung dieser Abfälle zusammengefasst und die Entscheidungsprozesse in Deutschland diskutiert. A historical overview of the options for solidification of liquid highly radioactive wastes is presented, which has been developed since the end of the 1950s. Starting from the boundary conditions of the reprocessing of spent nuclear fuel, possible methods and strategies for solidification of this wastes are summarized and the decision-making processes in Germany are discussed.

Ausgehend von den politischen und gesellschaftlichen Randbedingungen werden die Forschungs- und Entwicklungsarbeiten zur sicheren Endlagerung radioaktiver Abfälle, wie sie im Kernforschungszentrum Karlsruhe im Institut für Nukleare Entsorgung durchgeführt wurden, zusammengestellt. Die Organisationformen und die jeweils wesentlichen Forschungsthemen werden genannt sowie die gegenwärtigen Forschungsthemen und die Einbindung des Instituts in Lehre und Ausbildung und in Beratungsaufgaben. Research and development for safe disposal of radioactive wastes at the Nuclear Research Center Karlsruhe in the Institute of Nuclear Waste Disposal is presented. The political and societal boundary conditions for this R&D are referred to. The past organizational forms and the most important research topics are addresses as well as the current research topics including the involvement of the institute in training and education or consultation services.

This review describes the organic inventory in the wastes in German facilities, the microbial processes, such as aerobic and anaerobic processes, sulfate reduction, pH and ionic strength ranges and chaotropic effects on microbial activity. The microbial effects are discussed for resident and introduced microorganisms and the environmental conditions. The microbial population above the Gorleben salt dome and their effects of microorganisms on the retention of technetium and selenium are shown.

The EURATOM FP7 Collaborative Project “Fast / Instant Release of Safety Relevant Radionuclides from Spent Nuclear Fuel (CP FIRST-Nuclides)” improved significantly the understanding of the mobilization of dose-dominating radionuclides from high burnup spent nuclear UO₂ fuels. The data are decisive for safety analysis for deep geological nuclear waste repositories.

Since 1967 radioactive wastes have been disposed of in the Asse II salt mine in Northern Germany. A signifi-cant part of these wastes originated from the pilot reprocessing plant WAK in Karlsruhe and consisted of cemented NaNO3 solutions bearing fission products, actinides, as well as process chemicals. With respect to the long-term behavior of these wastes, the licensing authorities requested leaching experiments with full scale samples in relevant salt solutions which were performed since 1979. The experiments aimed at demonstrating the transferability of results obtained with laboratory samples to real waste forms and at the investigation of the effects of the industrial cementation process on the properties of the waste forms. This research program lasted until 2013. The corroding salt solutions were sampled several times and after termination of the experiments, the solid materials were analyzed by various methods. The results present-ed in this report cover the evolution of the solutions and the chemical and mineralogical characterization of the solids including radionuclides and waste components, and the paragenesis of solid phases (corrosion products). The outcome is compared to the results of model calculations. For safety analysis, conclusions are drawn on radionuclide retention, evolution of the geochemical environment, evolution of the density of solutions, and effects of temperature and porosity of the cement waste simulates on cesium mobilization.