Date of Award
Open Access Thesis
Travis W. Knight
Ceramic waste forms have been proposed to replace the traditional glassy waste forms for long term stabilization of radionuclides. These waste forms are constantly exposed to self-irradiation emitted from the constituent radionuclides causing their material properties to change accordingly. It has been known that the radiation damage in waste forms is dominated by alpha particles emitted from transuranic (TRU) radionuclides. Since alpha particles usually have a range of 10~20 μm in such waste forms, some fraction of any non-transuranic containing phases (for a multiphase waste form) will be undamaged (or less damaged) if containing large enough grain sizes. Modeling and simulation of such radiation damage is important for both designing and analyzing ceramic waste forms. Considering this, a method that utilizes computer codes, MCNP6.2 and TRIM, is developed for computing damage measured in atomic displacements created in such waste forms. This work builds upon earlier work that created a Multiphysics Object Oriented Simulation Environment (MOOSE) based application called TREX capable of modeling radionuclide diffusion in a multiphase waste form. The method is introduced using an example that simulates alpha particles originating from a pyrochlore phase and initiating damage within that phase and in any neighboring phases including a possible hollandite phase as may be present in a multiphase waste form. Alpha particle irradiation induced primary knock-on atom (PKA) energy data from TRIM is used as an input to the Norgett- Robinson-Torrens (NRT) calculation of displacement. Together with the positional dependent particle current information from MCNP, damage (displacement) distribution in hollandite is thereby calculated. A MOOSE Object is created and added to the MOOSE based application, TREX, for analyzing the actual damage distribution in a complex multiphase waste form.
Chen, Z.(2020). Computational Modeling of Radiation Damage in a Multi-Phase Ceramic Waste Form Using MOOSE. (Master's thesis). Retrieved from https://scholarcommons.sc.edu/etd/6116