On Safe Nuclear Waste Disposal, Characterization, Quality Control, and the Numerical Assessment of Radioactive Waste Properties

Managing the safe disposal of radioactive waste is a contemporary scientific challenge, regardless whether to maintain or step-in or step-out of societal nuclear energy utilization. For sure, an increasing number of nuclear facilities is going into decommissioning and a vast pile of legacy waste to be disposed of safely in addition to the accumulated HLW are waiting for safe disposal, world-wide. This requires proper characterizing the ingredient content to understand ways and mechanism of potential physical and chemical interaction of the waste components with its ambient environment. And predictions of these interactions have to be made assuring the absence of any interference with the surface biosphere over many hundreds of thousand years. Comprehensive characterization of the radio-toxic inventory allows for proper definition of a source-term for the analysis of repository safety. This helps understanding the microscopic and potentially slow-motioninteraction of waste compounds with the embedding geological material and helps transposing these results into very long-term safe and sound predictions. Sampling and full scale analyses may determine safe nuclideinventory spectrum, NDA-methods are easier to employ but would generally determine less precise information. This is much complemented with numerical assessment based on correlations between nuclidesderived from their chemo-physical similarities. However, there are limits to the proper applicability of commonly used correlations, and the valid parameter space and uncertainty propagation needs to be evaluated. We will report on our approach to address some pivotal aspects of the safe nuclear waste disposal methods and metrology and the progress of numerical assessment of parameter correlations from ab initio modeling.