Tübingen, University, Diss., 2004.

High-level radioactive waste (HLW) poses threat to the biosphere. Geological disposal is accepted as a safe way for HLW disposal. Waste canisters made of Sintered Silicon Carbide (SSiC) are proposed and geomechanical safety aspects relating to such SSiC canisters are investigated. First part of the thesis reviews the state-of-the-art and demands for HLW disposal. The reason for considering Silicon Carbide (SiC) as canister material is explained. Especially in terms of corrosion and lifetime, ceramics and especially SiC is superior to metals or concrete. The only concern is its brittle behavior. The second part of the thesis presents results on static and dynamic mechanical properties of SiC in general and in particular for SSiC based on literature review and own lab tests. Although strength values for SiC and especially SSiC are very high, the extreme brittle behavior has to be considered in case of impact or point-like loading. The third and most extensive part of the thesis part contains numerical simulations, which consider most critical potential loading situations during transport and installation of the canisters underground. Both, pure elastic continuum and DEM based models are used considering the following loading situations (critical scenarios): Freefall of canister during transport or installation (FF), Impact by falling rock block at disposal site (RF), Point loading due to accidental insertion of small stone below the canister (PL), Anisotropic earth pressure loading after disposal (EP). Coating to protect the canisters against damage is investigated and preliminary parameters in terms of stiffness and thickness are recommended.

Techn. Universiẗat, Diss., 2005--Darmstadt.

Im Mai 2017 wurde das „Gesetz zur Suche und Auswahl eines Standortes für ein Endlager für hochradioaktive Abfälle“ (Standortauswahlgesetz -StandAG) vom Bundestag und Bundesrat neu verabschiedet. In diesem Gesetz sind sämtliche Kriterien (geowissenschaftliche Kriterien, planungswissenschaftliche Kriterien, Kriterien für Sicherheitsuntersuchungen) erstmals gesetzlich festgelegt, die für die zukünftige Auswahl eines Standortes für ein Endlager für hoch radioaktive Wärme entwickelnde Abfälle (ausgediente Brennelemente und Abfälle aus der Wiederaufarbeitung bestrahlter Brennelemente) in Deutschland gelten. Die Kriterien sind vorab durch die „Kommission Lagerung hochradioaktiver Abfallstoffe“ (Endlagerkommission) in zweijähriger Arbeit von 2014 bis 2016 in kontroverser Diskussion festgelegt worden. In diesem Beitrag werden die geowissenschaftlichen Kriterien und die Phasen im Standortauswahlverfahrens kurz vorgestellt. Der Autor war Mitglied der Endlagerkommission. / In May 2017, the 'Act on the Search for and Selection of a Site for a Repository for Highly Radioactive Waste' (Site Selection Act - StandAG) was passed by the German “Bundestag” and “Bundesrat”. This Act for the first time defines by law all the criteria (geoscientific criteria, planning criteria, criteria for safety investigations) that apply to the future selection of a site for a repository for high-level radioactive, heat-generating waste (spent fuel elements and waste from the reprocessing of spent fuel elements) in Germany. The criteria have been defined in advance by the 'Commission on the Storage of Highly Radioactive Waste Materials' (Final Storage Commission; “Endlagerkommission”) in a controversial discussion during two years of work from 2014 to 2016. In this article, the geoscientific criteria and the phases in the site selection process are briefly presented. The author was member of the Repository Commission.