Behavior of ceria as an actinide surrogate in electroslag remelting and refining slags

Downsizing and decommissioning of nuclear facility operations is increasing the stockpile of various different grades of radioactive scrap iron (RSI). Disposal of this material not only represents significant resource and value lost but also necessitates long term monitoring for environmental compliance. The latter results in additional recurring expense. It is desirable to be able to decontaminate the RSI to a very low level that can be recycled or used for fabrication of containers for RSI disposal instead of using virgin metal to fabricate the container. Electroslag remelting and refining (ESR) is often used for decontaminating radioactive contaminated sources of scrap iron, such as stainless steel. Nonradioactive oxides of cerium are used to simulate the radioactive oxide contaminants of uranium and plutonium. The success of the ESR process is strongly dependent on having the right thermo-physical-and-chemical slag properties. In this article, we measured the following relevant slag properties: capacity to incorporate the radioactive contaminant (simulant), volatilization rate and volatile species, electrical conductivity, viscosity, surface tension, and slag-metal partition coefficient, as a function of temperature. The impact of these properties on the ESR decontamination process is discussed.     

Analysis of composite hydrogen storage cylinders subjected to localized flame impingements

A comprehensive non-linear finite element model is developed for predicting the behavior of composite hydrogen storage cylinders subjected to high pressure and localized flame impingements. The model is formulated in an axi-symmetric coordinate system and incorporates with various sub-models to describe the behavior of the composite cylinder under extreme thermo-mechanical loadings. A heat transfer sub-model is employed to predict the temperature evolution of the composite cylinder wall and accounts for heat transport due to decomposition and mass loss. A composite decomposition sub-model described by Arrhenius's law is implemented to predict the residual resin content of thermal damaged area. A sub-model for material degradation is implemented to account for the loss of mechanical properties. A progressive failure model is adopted to detect various types of mechanical failure. These sub-models are implemented in ABAQUS commercial finite element code using user subroutines. Numerical results are presented for thermal damage, residual properties and profile of resin content in the cylinder. The developed model provides a useful tool for safe design and structural assessment of high pressure composite hydrogen storage cylinders.